Multivariable Sensors for Ubiquitous Monitoring of Gases in the Era of Internet of Things and Industrial Internet
物联网和工业互联网时代用于无处不在的气体监测的多变量传感器
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GE Global Research, Niskayuna, New York 12309, United States
*E-mail: potyrailo@ge.com
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Abstract 抽象
Modern gas monitoring scenarios for medical diagnostics, environmental surveillance, industrial safety, and other applications demand new sensing capabilities. This Review provides analysis of development of new generation of gas sensors based on the multivariable response principles. Design criteria of these individual sensors involve a sensing material with multiresponse mechanisms to different gases and a multivariable transducer with independent outputs to recognize these different gas responses. These new sensors quantify individual components in mixtures, reject interferences, and offer more stable response over sensor arrays. Such performance is attractive when selectivity advantages of classic gas chromatography, ion mobility, and mass spectrometry instruments are canceled by requirements for no consumables, low power, low cost, and unobtrusive form factors for Internet of Things, Industrial Internet, and other applications. This Review is concluded with a perspective for future needs in fundamental and applied aspects of gas sensing and with the 2025 roadmap for ubiquitous gas monitoring.
用于医疗诊断、环境监测、工业安全和其他应用的现代气体监测场景需要新的传感功能。本文综述了基于多变量响应原理的新一代气体传感器的发展。这些传感器的设计标准包括具有对不同气体的多响应机制的传感材料，以及具有独立输出的多变量传感器，以识别这些不同的气体响应。这些新型传感器可量化混合物中的单个组件，抑制干扰，并提供比传感器阵列更稳定的响应。当传统气相色谱、离子淌度和质谱仪器的选择性优势被物联网、工业互联网和其他应用对无耗材、低功耗、低成本和不显眼的外形的要求所抵消时，这种性能就很有吸引力。本综述总结了气体传感基础和应用方面的未来需求，以及 2025 年无处不在的气体监测路线图。
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1 Introduction 1 引言
ARTICLE SECTIONS
Jump To
文章部分J- Abstract
- 1 Introduction
- 2 Diversity of Applications and Requirements for Modern Gas Sensors
- 3 State of the Art of Existing Sensing Concepts
- 4 General Principles of Multivariable Sensors
- 5 Multivariable Nonresonant and Resonant Impedance Sensors
- 6 Electromechanical Multivariable Resonant Sensors
- 7 Multivariable Field-Effect Transistor Sensors
- 8 Multivariable Photonic Resonant Sensors
- 9 Other Multivariable Sensor Technologies
- 10 Design Criteria for Multivariable Sensors
- 11 Benefits of Multivariable Sensors
- 12 Summary and Development Trends of Single-Output and Multivariable Sensors
- Author Information
- Biography
- Acknowledgment
- References
- Cited By
Monitoring of gas-phase chemicals such as gases and vapors using portable instruments has been traditionally important in numerous applications including industrial and home safety, environmental surveillance, process monitoring, homeland security, and others. (1-3) To meet diverse detection needs, developed complementary technologies include direct spectroscopy, gas chromatography, mass spectrometry, ion mobility spectrometry, and chemical sensors.
传统上，使用便携式仪器监测气相化学品（如气体和蒸汽）在许多应用中都很重要，包括工业和家庭安全、环境监测、过程监测、国土安全等。（1-3） 为了满足多样化的检测需求，开发了直接光谱、气相色谱、质谱、离子淌度谱和化学传感器等互补技术。
传统上，使用便携式仪器监测气相化学品（如气体和蒸汽）在许多应用中都很重要，包括工业和家庭安全、环境监测、过程监测、国土安全等。（1-3） 为了满足多样化的检测需求，开发了直接光谱、气相色谱、质谱、离子淌度谱和化学传感器等互补技术。
Sensors for monitoring of “gases” (such as any gas-phase chemicals) where a sensing material is applied onto a suitable physical transducer (4, 5) have a suite of attractive operational advantages over other portable instruments. These advantages include tunable sensitivity, continuous real-time determination of the concentrations of specific sample constituents, small power consumption, operation without consumables, and unobtrusive form factors. Unfortunately, existing sensors also have several performance limitations such as high cross-sensitivity and poor selectivity to various gases, (6) inability to preserve detection accuracy in the presence of unknown interferences, and sensor drift, especially noticeable in outdoor applications and in detection of low analyte levels. As a result, these limitations often can revoke advantages of sensors in their intended practical applications. Thus, field uses of gas sensors are often most successful when their poor selectivity is not important, concentrations of measured gases are high enough to make the sensor drift unnoticed, or frequent recalibration is acceptable. (7, 8)
用于监测“气体”（如任何气相化学品）的传感器，将传感材料施加到合适的物理传感器（4,5）上，与其他便携式仪器相比，具有一系列有吸引力的操作优势。这些优点包括可调灵敏度、连续实时测定特定样品成分的浓度、功耗小、无需耗材即可操作以及不显眼的外形尺寸。遗憾的是，现有的传感器也存在一些性能限制，例如交叉灵敏度高，对各种气体的选择性差，（6）在存在未知干扰的情况下无法保持检测精度，以及传感器漂移，在户外应用和低分析物水平检测中尤为明显。因此，这些局限性往往会削弱传感器在其预期实际应用中的优势。因此，当气体传感器的选择性差并不重要，被测气体的浓度高到足以使传感器漂移不被注意，或者频繁重新校准是可以接受的时，气体传感器的现场使用通常是最成功的。(7, 8)
用于监测“气体”（如任何气相化学品）的传感器，将传感材料施加到合适的物理传感器（4,5）上，与其他便携式仪器相比，具有一系列有吸引力的操作优势。这些优点包括可调灵敏度、连续实时测定特定样品成分的浓度、功耗小、无需耗材即可操作以及不显眼的外形尺寸。遗憾的是，现有的传感器也存在一些性能限制，例如交叉灵敏度高，对各种气体的选择性差，（6）在存在未知干扰的情况下无法保持检测精度，以及传感器漂移，在户外应用和低分析物水平检测中尤为明显。因此，这些局限性往往会削弱传感器在其预期实际应用中的优势。因此，当气体传感器的选择性差并不重要，被测气体的浓度高到足以使传感器漂移不被注意，或者频繁重新校准是可以接受的时，气体传感器的现场使用通常是最成功的。(7, 8)
Given the tremendous interest of the chemical research community in improving selectivity of sensor systems (50 000+ publications on “selectivity of gas or vapor sensors”), this Review provides a critical analysis of the recent progress in the development of a new generation of gas sensors based on the multivariable response principles to overcome the insufficient gas-selectivity limitation of existing sensors.
鉴于化学研究界对提高传感器系统选择性的极大兴趣（50 000+篇关于“气体或蒸汽传感器的选择性”的出版物），本综述对基于多变量响应原理的新一代气体传感器开发的最新进展进行了批判性分析，以克服现有传感器的气体选择性限制不足。
鉴于化学研究界对提高传感器系统选择性的极大兴趣（50 000+篇关于“气体或蒸汽传感器的选择性”的出版物），本综述对基于多变量响应原理的新一代气体传感器开发的最新进展进行了批判性分析，以克服现有传感器的气体选择性限制不足。
The design criteria of these individual multivariable sensors involve a sensing material with multiresponse mechanisms to different gases and a multivariable transducer with several partially or fully independent outputs to recognize these different gas responses. Performance capabilities of inorganic, organic, polymeric, biological, composite, and formulated sensing materials are discussed that have been explored for multivariable gas sensing. These sensing materials, when coupled with electrical, optical, and electromechanical transducers designed for operation in a multivariable mode, provide performance capabilities previously unavailable from conventional sensor systems. These new individual sensors quantify individual components in gas mixtures, reject interferences, and have a self-correction ability against environmental instabilities. These new performance characteristics will be attractive in established and emerging sensing scenarios.
这些单独的多变量传感器的设计标准包括具有对不同气体的多响应机制的传感材料，以及具有多个部分或完全独立输出的多变量传感器，以识别这些不同的气体响应。讨论了无机、有机、聚合物、生物、复合材料和配方传感材料在多变量气体传感中的性能能力。这些传感材料与设计用于多变量模式下的电、光学和机电传感器配合使用时，可提供传统传感器系统以前无法提供的性能。这些新型传感器可量化气体混合物中的单个成分，抑制干扰，并具有针对环境不稳定性的自我校正能力。这些新的性能特征在已建立和新兴的传感场景中将具有吸引力。
这些单独的多变量传感器的设计标准包括具有对不同气体的多响应机制的传感材料，以及具有多个部分或完全独立输出的多变量传感器，以识别这些不同的气体响应。讨论了无机、有机、聚合物、生物、复合材料和配方传感材料在多变量气体传感中的性能能力。这些传感材料与设计用于多变量模式下的电、光学和机电传感器配合使用时，可提供传统传感器系统以前无法提供的性能。这些新型传感器可量化气体混合物中的单个成分，抑制干扰，并具有针对环境不稳定性的自我校正能力。这些新的性能特征在已建立和新兴的传感场景中将具有吸引力。
This Review has four broad goals in order to stimulate research in this rapidly expanding multidisciplinary area.
本综述有四大目标，以促进这一快速扩展的多学科领域的研究。
本综述有四大目标，以促进这一快速扩展的多学科领域的研究。
The first goal is to deliver critical analysis of recent developments of sensors based on the multivariable response principles as provided by the number of independent outputs generated by the sensor (also known as sensor dispersion).
第一个目标是根据传感器产生的独立输出数量（也称为传感器色散）提供的多变量响应原理，对传感器的最新发展进行批判性分析。
第一个目标是根据传感器产生的独立输出数量（也称为传感器色散）提供的多变量响应原理，对传感器的最新发展进行批判性分析。
The second goal is to summarize the design criteria for a new generation of individual sensors based on diverse transducers (e.g., electrical, photonic, electromechanical, and other transducers) developed to operate in a multivariable mode when coupled with inorganic, organic, polymeric, and composite sensing materials.
第二个目标是总结基于各种传感器（例如，电气、光子、机电和其他传感器）的新一代单个传感器的设计标准，这些传感器在与无机、有机、聚合物和复合传感材料耦合时以多变量模式运行。
第二个目标是总结基于各种传感器（例如，电气、光子、机电和其他传感器）的新一代单个传感器的设计标准，这些传感器在与无机、有机、聚合物和复合传感材料耦合时以多变量模式运行。
The third goal is to compare performance of individual multivariable sensors and conventional sensor arrays and to illustrate that modern multivariable sensors are a disruptive sensor technology.
第三个目标是比较单个多变量传感器和传统传感器阵列的性能，并说明现代多变量传感器是一种颠覆性的传感器技术。
第三个目标是比较单个多变量传感器和传统传感器阵列的性能，并说明现代多变量传感器是一种颠覆性的传感器技术。
The fourth goal is to present a 2025 roadmap for multivariable gas sensors with the analysis of the significant driving forces in sensor developments.
第四个目标是提出 2025 年多变量气体传感器路线图，并分析传感器发展的重要驱动力。
第四个目标是提出 2025 年多变量气体传感器路线图，并分析传感器发展的重要驱动力。
The Review is structured in 11 sections. Diverse applications and requirements for modern gas sensors are summarized in section 2. Existing sensing concepts are analyzed in section 3, followed by the discussion of principles of multivariable sensors in section 4. A critical analysis of diverse types of multivariable sensors and associated sensing materials is provided in sections 5–9. This analysis is accomplished by the type of multivariable transducer that governs design choices for particular sensing materials. Discussed multivariable sensors include nonresonant and resonant impedance sensors (section 5), electromechanical resonant sensors (section 6), field-effect transistors (section 7), photonic resonant sensors (section 8), and other multivariable sensor technologies (section 9). The design criteria for diverse types of multivariable sensors are summarized in section 10. Benefits of multivariable sensors are further summarized in comparison with conventional sensor arrays in section 11. The outlook and the roadmap for multivariable gas sensors are presented in section 12.
本次审查分为11个部分。第2节总结了现代气体传感器的各种应用和要求。第3节分析了现有的传感概念，第4节讨论了多变量传感器的原理。第 5-9 节对不同类型的多变量传感器和相关传感材料进行了批判性分析。该分析由多变量传感器类型完成，该传感器控制特定传感材料的设计选择。讨论的多变量传感器包括非谐振和谐振阻抗传感器（第5节）、机电谐振传感器（第6节）、场效应晶体管（第7节）、光子谐振传感器（第8节）和其他多变量传感器技术（第9节）。第10节总结了各种类型多变量传感器的设计标准。第11节进一步总结了多变量传感器与传统传感器阵列相比的优点。第12节介绍了多变量气体传感器的前景和路线图。
本次审查分为11个部分。第2节总结了现代气体传感器的各种应用和要求。第3节分析了现有的传感概念，第4节讨论了多变量传感器的原理。第 5-9 节对不同类型的多变量传感器和相关传感材料进行了批判性分析。该分析由多变量传感器类型完成，该传感器控制特定传感材料的设计选择。讨论的多变量传感器包括非谐振和谐振阻抗传感器（第5节）、机电谐振传感器（第6节）、场效应晶体管（第7节）、光子谐振传感器（第8节）和其他多变量传感器技术（第9节）。第10节总结了各种类型多变量传感器的设计标准。第11节进一步总结了多变量传感器与传统传感器阵列相比的优点。第12节介绍了多变量气体传感器的前景和路线图。
2 Diversity of Applications and Requirements for Modern Gas Sensors
2 现代气体传感器的应用和要求的多样性
ARTICLE SECTIONS
Jump To
文章部分J- Abstract
- 1 Introduction
- 2 Diversity of Applications and Requirements for Modern Gas Sensors
- 3 State of the Art of Existing Sensing Concepts
- 4 General Principles of Multivariable Sensors
- 5 Multivariable Nonresonant and Resonant Impedance Sensors
- 6 Electromechanical Multivariable Resonant Sensors
- 7 Multivariable Field-Effect Transistor Sensors
- 8 Multivariable Photonic Resonant Sensors
- 9 Other Multivariable Sensor Technologies
- 10 Design Criteria for Multivariable Sensors
- 11 Benefits of Multivariable Sensors
- 12 Summary and Development Trends of Single-Output and Multivariable Sensors
- Author Information
- Biography
- Acknowledgment
- References
- Cited By
At present, “classic” analytical instruments based on gas chromatography (GC), mass spectrometry (MS), ion mobility spectrometry (IMS), and direct spectroscopy are preferred for high-selectivity detection, despite their relatively large power demands, cost, and size. (9, 10) These instruments could be inconvenient, even in portable configurations with the reduced carrier gas, vacuum, and power demands, (11) but are an unavoidable alternative over existing sensors.
目前，基于气相色谱（GC）、质谱（MS）、离子淌度谱（IMS）和直接光谱的“经典”分析仪器是高选择性检测的首选，尽管它们的功率要求、成本和尺寸相对较大。(9, 10)即使在便携式配置中，这些仪器也可能不方便，因为载气、真空和功率需求较低，（11），但与现有传感器相比，这些仪器是不可避免的替代方案。
目前，基于气相色谱（GC）、质谱（MS）、离子淌度谱（IMS）和直接光谱的“经典”分析仪器是高选择性检测的首选，尽管它们的功率要求、成本和尺寸相对较大。(9, 10)即使在便携式配置中，这些仪器也可能不方便，因为载气、真空和功率需求较低，（11），但与现有传感器相比，这些仪器是不可避免的替代方案。
Meanwhile, there are numerous scenarios when high-selectivity advantages of “classic” analytical instruments even in their microfabricated implementations would be canceled by specific application requirements (e.g., unobtrusive form factor, no external power for operation, no vacuum or carrier gases, no radioactive sources). The most prominent of these scenarios are Internet of Things and Industrial Internet applications. The Internet of Things is the network of everyday objects with embedded sensors and connectivity to increase the value of these objects by exchanging data with the users and other devices. (12, 13) The Industrial Internet is the integration of complex machinery with networked sensors. (14)
同时，在许多情况下，“经典”分析仪器的高选择性优势，即使在微加工实施中，也会被特定的应用要求（例如，不显眼的外形尺寸、无外部电源、无真空或载气、无放射源）所抵消。其中最突出的是物联网和工业互联网应用。物联网是具有嵌入式传感器和连接的日常物品网络，通过与用户和其他设备交换数据来增加这些物品的价值。(12, 13)工业互联网是复杂机械与联网传感器的集成。(14)
同时，在许多情况下，“经典”分析仪器的高选择性优势，即使在微加工实施中，也会被特定的应用要求（例如，不显眼的外形尺寸、无外部电源、无真空或载气、无放射源）所抵消。其中最突出的是物联网和工业互联网应用。物联网是具有嵌入式传感器和连接的日常物品网络，通过与用户和其他设备交换数据来增加这些物品的价值。(12, 13)工业互联网是复杂机械与联网传感器的集成。(14)
Exemplary existing and emerging applications of sensors are summarized in Figure 1 and include environmental monitoring and protection, industrial safety and manufacturing process control, monitoring of agricultural emissions, public safety, medical systems, wearable health and fitness, automation of residential homes and industrial buildings, transportation, and retail. (15-23) Examples of classes and types of measured gases and volatiles of interest for these applications include environmental background (e.g., O2, CO2, and H2O), transportation/industrial/agricultural atmospheric pollutants (e.g., CO2, CO, O3, H2S, NH3, NOx, SO2, CH4, industrial fumes, and waste odors), breath biomarkers (e.g., NO, H2S, NH4, acetone, ethane, pentane, isoprene, and hydrogen peroxide), and public/homeland safety hazardous volatiles (e.g., toxic industrial chemicals, chemical warfare agents, and explosives). (18, 24-28) Diverse types of volatiles need to be monitored over their broad range of concentrations ranging from part-per-trillion to percent, often mixed with chemical interferences such as ubiquitous variable background (indoor and outdoor urban air, industrial air, human odors and breath, exhaust of transportation engines, etc.) and at expected operation temperatures (ambient indoor and outdoor temperatures, body temperature, and exhaust of transportation engines).
图 1 总结了传感器的现有和新兴应用示例，包括环境监测和保护、工业安全和制造过程控制、农业排放监测、公共安全、医疗系统、可穿戴健康和健身、住宅和工业建筑自动化、运输和零售。（15-23） 这些应用所关注的测量气体和挥发物的类别和类型示例包括环境背景（例如，O 2 、CO 2 和H 2 O）、运输/工业/农业大气污染物（例如，CO 2 、CO、O 3 、H 2 S、NH 3 、NO x 、SO 2 、CH 4 、工业烟雾和废物气味）、呼吸生物标志物（例如，NO、H 2 S、NH 4 、丙酮、乙烷、戊烷、异戊二烯和过氧化氢）以及公共/国土安全危险挥发物（例如有毒工业化学品、化学战剂和爆炸物）。(18, 24-28)需要监测各种类型的挥发物，其浓度范围从万亿分之一到百分比不等，通常与化学干扰混合在一起，例如无处不在的可变背景（室内和室外城市空气、工业空气、人类气味和呼吸、运输发动机尾气等）和预期的工作温度（室内和室外环境温度、体温、 和运输发动机的排气）。
图 1 总结了传感器的现有和新兴应用示例，包括环境监测和保护、工业安全和制造过程控制、农业排放监测、公共安全、医疗系统、可穿戴健康和健身、住宅和工业建筑自动化、运输和零售。（15-23） 这些应用所关注的测量气体和挥发物的类别和类型示例包括环境背景（例如，O 2 、CO 2 和H 2 O）、运输/工业/农业大气污染物（例如，CO 2 、CO、O 3 、H 2 S、NH 3 、NO x 、SO 2 、CH 4 、工业烟雾和废物气味）、呼吸生物标志物（例如，NO、H 2 S、NH 4 、丙酮、乙烷、戊烷、异戊二烯和过氧化氢）以及公共/国土安全危险挥发物（例如有毒工业化学品、化学战剂和爆炸物）。(18, 24-28)需要监测各种类型的挥发物，其浓度范围从万亿分之一到百分比不等，通常与化学干扰混合在一起，例如无处不在的可变背景（室内和室外城市空气、工业空气、人类气味和呼吸、运输发动机尾气等）和预期的工作温度（室内和室外环境温度、体温、 和运输发动机的排气）。
Figure 1 图1
Figure 1. Examples of diverse application scenarios of gas sensors in the Internet of Things and Industrial Internet applications. Image prepared by GE Global Research.
图 1.气体传感器在物联网和工业互联网应用中的多样化应用场景示例。图片由GE全球研究院提供。
At present, physical sensors dominate in Internet of Things applications—microphones, accelerometers, gyroscopes, and compasses are being shipped at ∼1 billion units each annually. (29) However, the market for physical, chemical, and biological sensors is expected to grow to a cumulative trillion units by 2022. (25, 30-32)
目前，物理传感器在物联网应用中占主导地位，麦克风、加速度计、陀螺仪和指南针的年出货量约为 10 亿台。（29） 然而，到 2022 年，物理、化学和生物传感器市场预计将累计增长到万亿台。(25, 30-32)
目前，物理传感器在物联网应用中占主导地位，麦克风、加速度计、陀螺仪和指南针的年出货量约为 10 亿台。（29） 然而，到 2022 年，物理、化学和生物传感器市场预计将累计增长到万亿台。(25, 30-32)
The top five requirements for modern sensors for Internet of Things and Industrial Internet applications include (1) reliability, to provide accurate readings in diverse environmental conditions; (2) low power, to extend battery life or to eliminate its need thus simplifying detection logistics; (3) low cost, to accommodate the need for their large deployed numbers; (4) appropriate real-time communication capability; and (5) data security. (33, 34) Applying a combination of these requirements to new sensors significantly enhances their value. In particular, having new sensors at low cost but with unreliable performance significantly limits their value. In contrast, a new generation of sensors is desired to be not only low cost but also as reliable as their more expensive traditional analytical devices and at a fraction of the power needed to operate. (35-39)
物联网和工业互联网应用对现代传感器的五大要求包括：（1）可靠性，在各种环境条件下提供准确的读数;（2）低功耗，延长电池寿命或消除其需求，从而简化检测流程;（3）成本低，以适应其部署人数大的需要;（4）适当的实时通信能力;（5）数据安全。(33, 34)将这些要求组合应用于新传感器可显著提高其价值。特别是，以低成本但性能不可靠的新传感器会大大限制其价值。相比之下，新一代传感器不仅成本低廉，而且与更昂贵的传统分析设备一样可靠，并且功率仅为运行所需功率的一小部分。(35-39)
物联网和工业互联网应用对现代传感器的五大要求包括：（1）可靠性，在各种环境条件下提供准确的读数;（2）低功耗，延长电池寿命或消除其需求，从而简化检测流程;（3）成本低，以适应其部署人数大的需要;（4）适当的实时通信能力;（5）数据安全。(33, 34)将这些要求组合应用于新传感器可显著提高其价值。特别是，以低成本但性能不可靠的新传感器会大大限制其价值。相比之下，新一代传感器不仅成本低廉，而且与更昂贵的传统分析设备一样可靠，并且功率仅为运行所需功率的一小部分。(35-39)
Aligned with these requirements, (33, 34) developments of new sensors have been already focusing on reliability, low power, and low cost. Diverse sensing materials have been improved by understanding the key degradation mechanisms and reducing their effects. Recent reports include improvement of stability and poison resistance of metal oxide semiconducting (MOS) sensors (40) and improvement stability of ligand-capped metal nanoparticles by new ligand-attachment chemistry. (41) Significant power reduction has been demonstrated for sensors that operate at elevated temperatures of hundreds of degrees. Established available catalytic and MOS sensors operate with 0.1–1 W power requirements. (42-44) that allow their long-term applications in stationary and short-term applications in battery-powered systems. Recent reduction of needed power was achieved by reducing the duty cycle of operation (45-47) and applying self-heating principles of sensor operation. (48-51) Reduced power, size, and cost provided opportunities for MOS sensors to be integrated into smartphones for monitoring of air pollution. (52) Reducing the operating temperature of MOS sensors was also demonstrated under controlled lab conditions. (53-57) The reduced-temperature operation of such MOS sensors changes the gas-detection mechanisms (58) and requires further significant theoretical and practical validation. Cost reduction is targeted in many recent reports that include wafer-level fabrication, (28, 50, 59) printing, (60-62) roll-to-roll, (63, 64) self-assembly, (65, 66) and other techniques.
根据这些要求，（33,34）新传感器的开发已经集中在可靠性、低功耗和低成本上。通过了解关键的降解机制并减少其影响，改进了各种传感材料。最近的报道包括通过新的配体附着化学方法提高金属氧化物半导体 （MOS） 传感器的稳定性和抗毒性 （40） 以及改善配体封端金属纳米颗粒的稳定性。（41） 对于在数百度高温下工作的传感器，已经证明可以显着降低功耗。现有的催化和MOS传感器的工作功率要求为0.1–1 W。（42-44） 允许它们在固定和电池供电系统中的短期应用中长期应用。最近，通过降低工作占空比（45-47）和应用传感器工作的自热原理，实现了所需功率的降低。（48-51） 功耗、尺寸和成本的降低为MOS传感器集成到智能手机中以监测空气污染提供了机会。（52） 在受控的实验室条件下，还演示了降低MOS传感器的工作温度。（53-57） 这种MOS传感器的低温操作改变了气体检测机制（58），需要进一步进行重要的理论和实践验证。最近的许多报告都以降低成本为目标，包括晶圆级制造、（28、50、59）印刷、（60-62）卷对卷、（63、64）自组装、（65、66）和其他技术。
根据这些要求，（33,34）新传感器的开发已经集中在可靠性、低功耗和低成本上。通过了解关键的降解机制并减少其影响，改进了各种传感材料。最近的报道包括通过新的配体附着化学方法提高金属氧化物半导体 （MOS） 传感器的稳定性和抗毒性 （40） 以及改善配体封端金属纳米颗粒的稳定性。（41） 对于在数百度高温下工作的传感器，已经证明可以显着降低功耗。现有的催化和MOS传感器的工作功率要求为0.1–1 W。（42-44） 允许它们在固定和电池供电系统中的短期应用中长期应用。最近，通过降低工作占空比（45-47）和应用传感器工作的自热原理，实现了所需功率的降低。（48-51） 功耗、尺寸和成本的降低为MOS传感器集成到智能手机中以监测空气污染提供了机会。（52） 在受控的实验室条件下，还演示了降低MOS传感器的工作温度。（53-57） 这种MOS传感器的低温操作改变了气体检测机制（58），需要进一步进行重要的理论和实践验证。最近的许多报告都以降低成本为目标，包括晶圆级制造、（28、50、59）印刷、（60-62）卷对卷、（63、64）自组装、（65、66）和其他技术。
This Review is focused on the development of multivariable sensors to achieve an improved reliability of their performance by their enhanced selectivity. Several topics are outside the scope of this Review. In particular, design-for-manufacturability and cost reduction of sensors are the topics of a recent review (67) addressing the demands for Internet of Things and Industrial Internet applications in volumes of billions and even trillions of sensors. (30, 32) Aspects for low-power operation and energy-harvesting approaches for sensors have been also recently reviewed. (68-71) Diverse architectures of wireless sensor networks have been recently reviewed as well. (72)
本综述的重点是多变量传感器的开发，以通过增强选择性来提高其性能的可靠性。有几个主题超出了本综述的范围。特别是，传感器的可制造性和降低成本是最近一篇评论的主题（67），该评论解决了数十亿甚至数万亿个传感器对物联网和工业互联网应用的需求。(30, 32)最近还审查了传感器的低功耗操作和能量收集方法的各个方面。（68-71） 最近还对无线传感器网络的各种架构进行了审查。(72)
本综述的重点是多变量传感器的开发，以通过增强选择性来提高其性能的可靠性。有几个主题超出了本综述的范围。特别是，传感器的可制造性和降低成本是最近一篇评论的主题（67），该评论解决了数十亿甚至数万亿个传感器对物联网和工业互联网应用的需求。(30, 32)最近还审查了传感器的低功耗操作和能量收集方法的各个方面。（68-71） 最近还对无线传感器网络的各种架构进行了审查。(72)
3 State of the Art of Existing Sensing Concepts
3 现有传感概念的最新技术
ARTICLE SECTIONS
Jump To
文章部分J- Abstract
- 1 Introduction
- 2 Diversity of Applications and Requirements for Modern Gas Sensors
- 3 State of the Art of Existing Sensing Concepts
- 4 General Principles of Multivariable Sensors
- 5 Multivariable Nonresonant and Resonant Impedance Sensors
- 6 Electromechanical Multivariable Resonant Sensors
- 7 Multivariable Field-Effect Transistor Sensors
- 8 Multivariable Photonic Resonant Sensors
- 9 Other Multivariable Sensor Technologies
- 10 Design Criteria for Multivariable Sensors
- 11 Benefits of Multivariable Sensors
- 12 Summary and Development Trends of Single-Output and Multivariable Sensors
- Author Information
- Biography
- Acknowledgment
- References
- Cited By
In gas sensing, a proper combination of a sensing material and a physical transducer is needed to achieve a desired sensor response (Figure 2A). Some of the most widely studied types of sensing materials are illustrated in Figure 2B–G (73-75) as examples for detection of reducing or oxidizing gases, volatile organic compounds, and combustible and toxic gases. A summary of diverse vapor-response mechanisms of several classes of sensing materials such as inorganic, organic, polymeric, biological, and composites is presented in Table 1. To probe a sensing material response upon gas exposures, numerous types of transducers were developed. Figure 2H–S (100-103) illustrates examples of such transducers that include electrical nonresonant and resonant transducers, electromechanical resonators, and optical transducers.
在气体传感中，需要传感材料和物理传感器的适当组合才能实现所需的传感器响应（图2A）。图2B-G（73-75）展示了一些研究最广泛的传感材料类型，作为检测还原性或氧化性气体、挥发性有机化合物以及可燃和有毒气体的示例。表1总结了无机、有机、聚合物、生物和复合材料等几类传感材料的不同蒸汽响应机制。为了探测气体暴露时的传感材料响应，开发了多种类型的换能器。图2H-S（100-103）说明了此类换能器的示例，包括电非谐振和谐振换能器、机电谐振器和光学换能器。
在气体传感中，需要传感材料和物理传感器的适当组合才能实现所需的传感器响应（图2A）。图2B-G（73-75）展示了一些研究最广泛的传感材料类型，作为检测还原性或氧化性气体、挥发性有机化合物以及可燃和有毒气体的示例。表1总结了无机、有机、聚合物、生物和复合材料等几类传感材料的不同蒸汽响应机制。为了探测气体暴露时的传感材料响应，开发了多种类型的换能器。图2H-S（100-103）说明了此类换能器的示例，包括电非谐振和谐振换能器、机电谐振器和光学换能器。
Figure 2 图2
Figure 2. Anatomy of conventional gas sensors. (A) Required proper combination of a sensing material and a physical transducer to achieve a desired sensor response. (B–G) Examples of sensing materials: (B) semiconducting metal oxide, (C) metal–organic framework, (73) (D) single-walled carbon nanotubes, (E) graphene, (F) gold nanoparticles functionalized with organic ligand, (74) and (G) atomic-layered molybdenum disulfide. (75) (H–S) Examples of physical transducers: electrical nonresonant transducers (H) resistor with interdigital electrodes, (I) capacitor, and (J) field effect transistor; (100) electrical resonant transducers (K) resistor–inductor–capacitor (RLC) resonant transducer with an integrated circuit memory chip as a passive radio frequency identification tag and sensor operating at ∼13 MHz, (L) coil-based transducer operating at ∼100 MHz, (M) dual-split-ring-based transducer operating at ∼5 GHz; electromechanical resonant transducers (N) thickness shear mode device, (O) acoustic wave device, (101) (P) microcantilever; (102) optical transducers (Q) reflected light opto-pair, (103) (R) distributed fiber-optic transducer, (S) localized plasmon resonance transducer. (102) (C) Reprinted with permission from ref 73. Copyright 2014 Nature Publishing Group. (F) Reprinted with permission from ref 74. Copyright 2013 Wiley-VCH Verlag GmbH & Co KGaA. (G) Reprinted with permission from ref 75. Copyright 2015 American Chemical Society. (J) Reprinted with permission from ref 100. Copyright 2012 American Chemical Society. (L) Logo pictured courtesy of General Electric.
图2.传统气体传感器的解剖结构。（A） 需要传感材料和物理换能器的适当组合，以实现所需的传感器响应。（B-G）传感材料的例子：（B）半导体金属氧化物，（C）金属有机框架，（73）（D）单壁碳纳米管，（E）石墨烯，（F）用有机配体官能化的金纳米颗粒，（74）和（G）原子层状二硫化钼。（75） （H-S） 物理换能器的例子：电非谐振换能器 （H） 带指间电极的电阻器、（I） 电容器和 （J） 场效应晶体管;（100） 电谐振换能器 （K） 电阻-电感-电容 （RLC） 谐振换能器，带有集成电路存储芯片作为无源射频识别标签和传感器，工作频率为 ∼13 MHz，（L） 基于线圈的换能器，工作频率为 ∼100 MHz，（M） 基于双分裂环的传感器，工作频率为 ∼5 GHz;机电谐振换能器（N）厚度剪切模式装置，（O）声波装置，（101）（P）微悬臂;（102）光换能器（Q）反射光光对，（103）（R）分布式光纤换能器，（S）局部等离子体共振换能器。（102） （C） 经参考文献 73 许可转载。版权所有 2014 Nature Publishing Group.（F） 经参考文献 74 许可转载。版权所有 2013 Wiley-VCH Verlag GmbH & Co KGaA。（G） 经参考文献 75 许可转载。版权所有 2015 美国化学学会。（J） 经参考文献 100 许可转载。版权所有 2012 美国化学学会。（L）徽标图片由通用电气提供。
Table 1. Gas-Response Mechanisms of Representative Sensing Materials
表 1.代表性传感材料的气体响应机理
表 1.代表性传感材料的气体响应机理
| sensing material 传感材料 | gas-response mechanisms 气体反应机制 | ref |
|---|---|---|
| dielectric polymers 介电聚合物 | dispersion, polarizability, dipolarity, basicity, acidity, and hydrogen-bonding interactions 色散、极化率、偶极性、碱度、酸度和氢键相互作用 | 76 |
| conjugated polymers 共轭聚合物 | changes in density and charge carrier mobility, swelling, and conformation transitions of chains 链密度和电荷载流子迁移率、膨胀和构象转变的变化 | 77, 78 |
| metalloporphyrins, phthalocyanines, related macrocycles 金属卟啉、酞菁、相关大环 | hydrogen bonding, polarization, polarity, metal center coordination interactions, π-stacking, and molecular arrangements 氢键、极化、极性、金属中心配位相互作用、π堆积和分子排列 | 79, 80 |
| cavitands 卡维坦德斯 | intracavity host–guest complexation with hydrogen bonding, CH-π, and dipole–dipole as the main specific interactions 以氢键、CH-π和偶极-偶极子为主要特异性相互作用的腔内主客络合 | 81 |
| zeolites 沸石 | molecular discrimination by size, shape, molecular kinetic diameter 通过大小、形状、分子动力学直径进行分子区分 | 82 |
| metal–organic frameworks 金属-有机框架 | van der Waals interactions of the framework surface, coordination to the central metal ion, hydrogen bonding of the framework surface, size exclusion 框架表面的范德华相互作用，与中心金属离子的配位，框架表面的氢键，尺寸排阻 | 83, 84 |
| metal oxides 金属氧化物 | physisorption, chemisorption, surface defects, and bulk defects depending on operation temperatures (ambient to ca. 1000 °C) and utilizing different metal oxides and dopants 物理吸附、化学吸附、表面缺陷和本体缺陷取决于工作温度（环境温度至约 1000 °C）并利用不同的金属氧化物和掺杂剂 | 85−87 |
| monolayer-protected metal nanoparticles 单层保护金属纳米颗粒 | electron tunneling between metal cores, charge hopping along the atoms of ligand shell 金属核之间的电子隧穿，电荷沿着配体壳层的原子跳跃 | 88, 89 |
| carbon nanotubes 碳纳米管 | charge transfer from analytes and polarization of surface adsorbates, gas-induced Schottky barrier modulation 分析物的电荷转移和表面吸附的极化、气体诱导的肖特基势垒调制 | 90, 91 |
| graphene 石墨烯 | charge transfer induced by adsorption/desorption of gaseous molecules acting as electron donors or acceptors, leading to changes in conductance 由充当电子供体或受体的气态分子的吸附/解吸引起的电荷转移，导致电导变化 | 92 |
| molybdenum disulfide 二硫化钼 | charge-transfer mechanism involving transient doping of sensing layer 涉及传感层瞬态掺杂的电荷转移机理 | 93, 94 |
| plasmonic nanoparticles with soft organic layers 具有软有机层的等离子体纳米颗粒 | changes in interparticle spacing, refractive index of the organic layer, and reflectivity of the metal nanoparticle network film 金属纳米颗粒网络膜的颗粒间距、有机层折射率和反射率的变化 | 74 |
| plasmonic nanoparticle/metal oxide nanocomposite films 等离子体纳米颗粒/金属氧化物纳米复合膜 | charge exchange with the nanoparticles, change in the dielectric constant surrounding the nanoparticles, dependent on the type of a metal oxide and its morphology for operation at 300–800 °C 与纳米颗粒的电荷交换，纳米颗粒周围介电常数的变化，取决于金属氧化物的类型及其在300-800°C下操作的形态 | 95 |
| colloidal crystals from core/shell nanospheres 来自核/壳纳米球的胶体晶体 | vapor-induced changes of optical lattice constant of colloidal crystal with cores and shells of nanospheres responding to diverse vapors 胶体晶体与纳米球核壳响应不同气气的光晶格常数的气相变化 | 96 |
| iridescent scales of tropical Morpho butterflies 热带 Morpho 蝴蝶的彩虹色鳞片 | lamella/ridge nanostructures with gradient of surface chemistry induce spatial control of sorption and adsorption of analytes and probed with light interference and diffraction 具有表面化学梯度的薄片/脊纳米结构诱导了分析物吸附和吸附的空间控制，并通过光干涉和衍射探测 | 97, 98 |
| bioinspired photonic interference-stack nanostructures 仿生光子干涉堆栈纳米结构 | chemically functionalized nanostructures with weak optical loss induce spatial control of sorption and adsorption of analytes probed with light interference and diffraction 具有弱光损耗的化学功能化纳米结构诱导了光干涉和衍射探测的分析物的吸附和吸附的空间控制 | 99 |
Recent important advances in gas sensors include outstanding sensitivity in vacuum and clean carrier gas (-90, 92, 104-108) and rapid response times. (105, 109-114) These improvements in sensitivity and response times of sensing materials were demonstrated with the reduction of size of sensing features down to zero-dimensional nanoparticles, one-dimensional nanowires, two-dimensional sheets, and three-dimensional nanostructures. Such size reduction allowed not only the higher surface area for the analyte to interact with the material but also implementation of new physical phenomena on the nanometer scale. (48, 109, 115) The major differences in gas sensitivity between diverse materials are their mechanisms of interaction with different classes of gases such as reducing or oxidizing gases, volatile organic compounds, and combustible and toxic gases at different temperatures ranging from ambient to ∼1000 °C as presented in Table 1.
气体传感器的最新重要进展包括对真空和清洁载气（-90、92、104-108）的出色灵敏度和快速响应时间。(105, 109-114)传感材料的灵敏度和响应时间的这些改进通过将传感特征的尺寸减小到零维纳米颗粒、一维纳米线、二维片和三维纳米结构得到了证明。这种尺寸的减小不仅使分析物与材料相互作用的表面积更大，而且还可以在纳米尺度上实现新的物理现象。(48, 109, 115)不同材料之间气体敏感性的主要区别在于它们在从环境温度到∼1000 °C的不同温度范围内与不同类别的气体（如还原性或氧化性气体、挥发性有机化合物以及可燃和有毒气体）的相互作用机制，如表1所示。
气体传感器的最新重要进展包括对真空和清洁载气（-90、92、104-108）的出色灵敏度和快速响应时间。(105, 109-114)传感材料的灵敏度和响应时间的这些改进通过将传感特征的尺寸减小到零维纳米颗粒、一维纳米线、二维片和三维纳米结构得到了证明。这种尺寸的减小不仅使分析物与材料相互作用的表面积更大，而且还可以在纳米尺度上实现新的物理现象。(48, 109, 115)不同材料之间气体敏感性的主要区别在于它们在从环境温度到∼1000 °C的不同温度范围内与不同类别的气体（如还原性或氧化性气体、挥发性有机化合物以及可燃和有毒气体）的相互作用机制，如表1所示。
Unfortunately, existing sensors have poor gas selectivity and insufficient stability. These features affect sensor reliability, which is one of the critical aspects for the broad acceptance of sensors. (33, 34) Often, new sensing materials respond not only to an intended analyte vapor but also to other vapors, for example, as shown in Figure 3A–C (116-118) exhibiting significant vapor cross-sensitivity. The origin of this limitation is in the conflicting requirements for sensor selectivity versus reversibility. (4) The full and fast reversibility of sensor response is achieved via weak interactions between the analyte and the sensing film, whereas the high selectivity of sensor response is achieved via strong interactions between the analyte vapor and the sensing film.
不幸的是，现有的传感器气体选择性差，稳定性不足。这些特性会影响传感器的可靠性，而传感器的可靠性是传感器被广泛接受的关键方面之一。(33, 34)通常，新的传感材料不仅对预期的分析物蒸气有反应，而且对其他蒸气也有反应，例如，如图3A-C（116-118）所示，表现出显著的蒸气交叉敏感性。这种限制的根源在于对传感器选择性与可逆性的相互冲突的要求。（4）传感器响应的完全快速可逆性是通过分析物与传感膜之间的弱相互作用实现的，而传感器响应的高选择性是通过分析物蒸气与传感膜之间的强相互作用来实现的。
不幸的是，现有的传感器气体选择性差，稳定性不足。这些特性会影响传感器的可靠性，而传感器的可靠性是传感器被广泛接受的关键方面之一。(33, 34)通常，新的传感材料不仅对预期的分析物蒸气有反应，而且对其他蒸气也有反应，例如，如图3A-C（116-118）所示，表现出显著的蒸气交叉敏感性。这种限制的根源在于对传感器选择性与可逆性的相互冲突的要求。（4）传感器响应的完全快速可逆性是通过分析物与传感膜之间的弱相互作用实现的，而传感器响应的高选择性是通过分析物蒸气与传感膜之间的强相互作用来实现的。
Figure 3 图3
Figure 3. Typical gas cross-sensitivity patterns of new types of reversible sensing materials. (A) Chemiresistor with a p-type semiconductor NiO—preferential response to formaldehyde over other volatiles. (116) (B) Polymeric sensing film formulated with two types of fluorescent phosphonate cavitands—fluorescence response to vapors of different alcohols. (117) (C) Thickness shear mode resonators with two types of immobilized DNA—response to model analytes. (118) (A) Reprinted with permission from ref 116. Copyright 2015 Elsevier. (B) Reprinted with permission from ref 117. Copyright 2011 Wiley-VCH Verlag GmbH & Co KGaA. (C) Reprinted with permission from ref 118. Copyright 2015 Elsevier.
图3.新型可逆传感材料的典型气体交叉敏感度模式。（A） 具有 p 型半导体 NiO 的化学电阻器——对甲醛的响应优于其他挥发物。（116） （B） 由两种类型的荧光膦酸盐空体配制的聚合物传感膜——对不同醇的蒸气的荧光响应。（117） （C） 具有两种固定化DNA的厚度剪切模式谐振器——对模型分析物的响应。（118） （A） 经参考文献 116 许可转载。版权所有 2015 Elsevier。（B） 经参考文献 117 许可转载。版权所有 2011 Wiley-VCH Verlag GmbH & Co KGaA。（C） 经参考文献 118 许可转载。版权所有 2015 Elsevier。
Insufficient vapor selectivity is also known for existing sensors. For qualitative comparison with new sensing materials, typical gas cross-sensitivity patterns of the most widely implemented types of commercially available materials-based sensors such as electrochemical, MOS, and catalytic combustion sensors (40, 119, 120) are visualized in Figure 4A–C. (40, 119, 120) This information is typically available in the sensor product specification and is utilized to estimate the expected levels of false alarms in anticipated applications. Such comparison illustrates that neither new nor established single-output sensors have a desired minimal gas cross-sensitivity.
对于现有的传感器来说，蒸汽选择性不足也是众所周知的。为了与新型传感材料进行定性比较，图4A–C中显示了最广泛实施的基于材料的商用传感器类型（如电化学、MOS和催化燃烧传感器（40、119、120）的典型气体交叉灵敏度模式。 （40， 119， 120） 此信息通常在传感器产品规格中提供，用于估计预期应用中预期的误报水平。这种比较表明，无论是新的还是现有的单输出传感器，都没有所需的最小气体交叉灵敏度。
对于现有的传感器来说，蒸汽选择性不足也是众所周知的。为了与新型传感材料进行定性比较，图4A–C中显示了最广泛实施的基于材料的商用传感器类型（如电化学、MOS和催化燃烧传感器（40、119、120）的典型气体交叉灵敏度模式。 （40， 119， 120） 此信息通常在传感器产品规格中提供，用于估计预期应用中预期的误报水平。这种比较表明，无论是新的还是现有的单输出传感器，都没有所需的最小气体交叉灵敏度。
Figure 4 图4
Figure 4. Typical gas cross-sensitivity patterns of established types of reversible sensing materials. (A) Electrochemical sensor calibrated for ethylene oxide. (119) (B) Metal oxide semiconductor sensor calibrated for methane. (40) (C) Catalytic combustion sensor calibrated for methane. (120)
图4.已建立类型的可逆传感材料的典型气体交叉敏感度模式。（A） 经过环氧乙烷校准的电化学传感器。（119） （B） 针对甲烷进行校准的金属氧化物半导体传感器。（40） （C） 甲烷校准的催化燃烧传感器。(120)
This problem of poor selectivity can be reduced by implementing sensing materials that utilize strong irreversible or slow-recovery chemical reactions. Recent examples of such developments are illustrated in Figure 5A–C. (75, 121, 122) This approach allows operation of a single sensing element for several dosimetric measurements followed by element replacement or element resetting using an external UV, thermal, or other type of energy.
通过采用利用强不可逆或慢恢复化学反应的传感材料，可以减少选择性差的问题。（75,121,122）这种方法允许操作单个传感元件进行多次剂量测量，然后使用外部紫外线、热能或其他类型的能量更换元件或重置元件。
通过采用利用强不可逆或慢恢复化学反应的传感材料，可以减少选择性差的问题。（75,121,122）这种方法允许操作单个传感元件进行多次剂量测量，然后使用外部紫外线、热能或其他类型的能量更换元件或重置元件。
Figure 5 图5
Figure 5. Typical gas cross-sensitivity patterns of gas dosimeter materials based on irreversible or slow-recovery chemical reactions. (A) Response of a reduced graphene oxide-decorated cotton yarn to NO2 (analyte) and other volatiles. (121) (B) Response of an atomic-layered MoS2 to NO2 (analyte) and other volatiles. (75) (C) Response of colorimetric formulated composition to formaldehyde (analyte) and other volatiles. (122) Insets in (A–C) are output signals of dosimeters (1) before, (2) during, and (3) after exposures to analytes. (A) Reprinted with permission from ref 121. Copyright 2015 Nature Publishing Group. (B) Reprinted with permission from ref 75. Copyright 2015 American Chemical Society. (C) Reprinted with permission from ref 122. Copyright 2015 Institute of Electrical and Electronics Engineers.
图5.基于不可逆或慢恢复化学反应的气体剂量计材料的典型气体交叉敏感模式。（A）还原氧化石墨烯装饰棉纱对NO 2 （分析物）和其他挥发物的响应。（121） （B） 原子层状MoS 2 对NO 2 （分析物）和其他挥发物的响应。（75） （C） 比色配制组合物对甲醛（分析物）和其他挥发物的响应。（122） （A-C）中的插图是剂量计（1）暴露于分析物之前、（2）期间和（3）暴露于分析物之后的输出信号。（A） 经参考文献 121 许可转载。版权所有 2015 Nature Publishing Group.（B） 经参考文献 75 许可转载。版权所有 2015 美国化学学会。（C） 经参考文献 122 许可转载。版权所有 2015 电气和电子工程师协会。
An evolution of gas-sensing concepts that had led to multivariable sensors is depicted in Figure 6. “Classic” gas sensors based on a single output (i.e., zero-order sensors (123)) are schematically depicted in Figure 6A. Such sensors have been recently extensively reviewed. (124-130) To improve selectivity, individual sensors are assembled into arrays where the output of the array is processed with multivariate analysis tools (Figure 6B). Examples of the most widely used tools for multivariate analysis of sensing data are summarized in Table 2.
图 6 描绘了导致多变量传感器的气体传感概念的演变。基于单输出的“经典”气体传感器（即零阶传感器（123））示意性地如图6A所示。这种传感器最近得到了广泛的审查。（124-130）为了提高选择性，将单个传感器组装成阵列，其中阵列的输出使用多变量分析工具进行处理（图6B）。表2总结了最广泛使用的传感数据多变量分析工具示例。
图 6 描绘了导致多变量传感器的气体传感概念的演变。基于单输出的“经典”气体传感器（即零阶传感器（123））示意性地如图6A所示。这种传感器最近得到了广泛的审查。（124-130）为了提高选择性，将单个传感器组装成阵列，其中阵列的输出使用多变量分析工具进行处理（图6B）。表2总结了最广泛使用的传感数据多变量分析工具示例。
Figure 6 图6
Figure 6. Evolution of gas-sensing concepts. (A) “Classic” single-output gas sensor with known insufficient selectivity. (B) Assembly of individual single-output sensors into an array and chemometric processing of the array output. (C) Individual gas sensor based on multivariable response principles.
图6.气体传感概念的演变。（A） “经典”单输出气体传感器，已知选择性不足。（B） 将单个单输出传感器组装到阵列中，并对阵列输出进行化学计量处理。（C） 基于多变量响应原理的单个气体传感器。
Table 2. Examples of Typical Chemometrics Tools Applied for Data Analysis of Sensor Arrays and Multivariable Sensors
表 2.用于传感器阵列和多变量传感器数据分析的典型化学计量学工具示例
表 2.用于传感器阵列和多变量传感器数据分析的典型化学计量学工具示例
| algorithm 算法 | description 描述 |
|---|---|
| principal component analysis (PCA) 主成分分析（PCA） | Unsupervised algorithm that reduces a multidimensional data set for its easier interpretation by calculating orthogonal principal components (PCs) oriented in the direction of the maximum variance within the data set. The first PC contains the highest degree of variance, and other PCs follow in the order of decreasing variance. Thus, PCA concentrates the most significant characteristics (variance) of the data into a lower dimensional space. 无监督算法，通过计算数据集内最大方差方向的正交主成分 （PC），减少多维数据集以便于解释。第一台 PC 包含最高程度的方差，其他 PC 按方差递减的顺序排列。因此，PCA 将数据的最显着特征（方差）集中到较低维的空间中。 |
| discriminant analysis (DA) 判别分析 （DA） | Models the difference between the classes of data and maximizes the ratio of between-class variance to the within-class variance. Requires an input of distinction between independent variables and dependent variables. 对数据类别之间的差异进行建模，并最大化类间方差与类内方差的比率。需要输入区分自变量和因变量的输入。 |
| artificial neural network (ANN) 人工神经网络 （ANN） | A system of a large number of simple highly interconnected processing elements (“neurons”) that exchange messages between each other to process information by their dynamic state response to external inputs. The connections have numeric weights that can be tuned based on experience, making neural nets adaptive to inputs and capable of learning. 一个由大量简单、高度互连的处理元件（“神经元”）组成的系统，它们相互交换消息，通过它们对外部输入的动态状态响应来处理信息。这些连接具有可以根据经验进行调整的数字权重，使神经网络能够适应输入并能够学习。 |
| hierarchical cluster analysis (HCA) 分层聚类分析 （HCA） | Classifies samples using a dendrogram representation. Often, a Ward’s method is applied that shows the Euclidean distance between the samples. The Ward’s method is a minimum variance method, which takes into consideration the minimum amount of variance between the samples and gases (analyte and interferents) to define a cluster. 使用树状图表示对样本进行分类。通常，应用沃德方法显示样本之间的欧几里得距离。沃德法是一种最小方差法，它考虑样品和气体（分析物和干扰物）之间的最小方差来定义集群。 |
| support vector machines (SVM) 支持向量机 （SVM） | Supervised learning models with associated learning algorithms that analyze data and recognize patterns, used for classification, regression analysis, and outliers detection by finding the decision hyperplane that maximizes the margin between the classes. The vectors (cases) that define the decision hyperplane are the support vectors. 具有相关学习算法的监督学习模型，用于分析数据和识别模式，用于分类、回归分析和异常值检测，方法是找到最大化类之间边际的决策超平面。定义决策超平面的向量（事例）是支持向量。 |
| independent component analysis (ICA) 独立成分分析 （ICA） | Separates a multivariate signal into additive subcomponents by assuming that the subcomponents are statistically mutually independent non-Gaussian signals. A powerful technique for revealing hidden factors that underlie sets of random variables, measurements, or signals. 通过假设多变量信号是统计上相互独立的非高斯信号，将多变量信号分割成加性子分量。一种强大的技术，用于揭示随机变量、测量值或信号集背后的隐藏因素。 |
| partial least-squares (PLS) regression 偏最小二乘 （PLS） 回归 | Determines correlations between the independent variables and the sensor response by finding the direction in the multidimensional space of the sensor response that explains the maximum variance for the independent variables. The key outputs of the developed multivariate models are residual errors of calibration and cross-validation. 通过在传感器响应的多维空间中查找解释自变量最大方差的方向，确定自变量与传感器响应之间的相关性。所开发的多变量模型的主要输出是校准和交叉验证的残余误差。 |
| principal component regression (PCR) 主成分回归 （PCR） | Regression analysis technique based on PCA by regressing the dependent variables on a set of independent variables based on a standard linear regression model, but uses PCA for estimating the unknown regression coefficients in the model. 基于PCA的回归分析技术，通过基于标准线性回归模型的一组自变量上的因变量回归，但使用PCA来估计模型中的未知回归系数。 |
Since the 1980s, combining sensors into arrays (131-134) is a common compromise to mitigate poor selectivity of individual conventional sensors as shown in excellent studies with sensor arrays containing up to 65 536 elements. (131, 135-140) The field of sensor arrays (also known as electronic noses) has matured to an understanding of their applicability and limitations outside controlled laboratory conditions (e.g., an uncorrelated drift of each sensor in an array, inability to provide accurate quantitation of multiple vapors in their mixtures, and inability to operate in the presence of high levels of known and unknown interferences). The state of the art in sensor arrays and their prospects has been critically analyzed in “classic” and recent reviews. (141-166) Sensor arrays can be also complimented with hyphenated methodologies where sensing materials are interrogated with different transducers to probe diverse properties of the material. Several “classic” and recent examples include sensor arrays based on several transduction principles, (167-170) probing organic semiconducting materials with thickness-shear mode and field-effect transducers, (171) probing carbon nanotubes with acoustic and optical readouts, (172) probing nanopore-sorbed volatiles with opto-calorimetric readout, (173) and probing adsorbed volatiles with piezotransistive and photoacoustic readouts. (174)
自 1980 年代以来，将传感器组合成阵列 （131-134） 是一种常见的折衷方案，以减轻单个传统传感器的选择性差，正如对包含多达 65 536 个元件的传感器阵列的出色研究表明的那样。(131, 135-140)传感器阵列（也称为电子鼻）领域已经成熟，可以理解它们在受控实验室条件之外的适用性和局限性（例如，阵列中每个传感器的不相关漂移，无法准确定量其混合物中的多种蒸汽，以及无法在存在高水平的已知和未知干扰的情况下运行）。传感器阵列的最新技术及其前景已在“经典”和最近的评论中进行了批判性分析。（141-166） 传感器阵列也可以与连字符方法相辅相成，其中传感材料使用不同的换能器进行询问，以探测材料的不同特性。一些“经典”和最近的例子包括基于几种转导原理的传感器阵列，（167-170）用厚剪切模式和场效应换能器探测有机半导体材料，（171）用声学和光学读数探测碳纳米管，（172）用光量热读数探测纳米孔吸附挥发物，（173）用压电透体和光声读数探测吸附挥发物。(174)
自 1980 年代以来，将传感器组合成阵列 （131-134） 是一种常见的折衷方案，以减轻单个传统传感器的选择性差，正如对包含多达 65 536 个元件的传感器阵列的出色研究表明的那样。(131, 135-140)传感器阵列（也称为电子鼻）领域已经成熟，可以理解它们在受控实验室条件之外的适用性和局限性（例如，阵列中每个传感器的不相关漂移，无法准确定量其混合物中的多种蒸汽，以及无法在存在高水平的已知和未知干扰的情况下运行）。传感器阵列的最新技术及其前景已在“经典”和最近的评论中进行了批判性分析。（141-166） 传感器阵列也可以与连字符方法相辅相成，其中传感材料使用不同的换能器进行询问，以探测材料的不同特性。一些“经典”和最近的例子包括基于几种转导原理的传感器阵列，（167-170）用厚剪切模式和场效应换能器探测有机半导体材料，（171）用声学和光学读数探测碳纳米管，（172）用光量热读数探测纳米孔吸附挥发物，（173）用压电透体和光声读数探测吸附挥发物。(174)
On the basis of the developments of single-output sensors, their arrays, and hyphenated readouts, a new generation of gas sensors is emerging that utilizes multivariable response principles (Figure 6C). Multivariable sensors and microanalytical systems producing multivariable response were reviewed in “classic” (175, 176) and recent reviews. (177-179) Critical analysis of the recent developments in multivariable sensors based on diverse transduction principles and their critical comparison is the focus of the next sections of this Review.
在单输出传感器、其阵列和连字符读数的发展基础上，利用多变量响应原理的新一代气体传感器正在出现（图6C）。在“经典”（175,176）和最近的综述中回顾了产生多变量响应的多变量传感器和微分析系统。（177-179） 对基于不同转导原理的多变量传感器的最新发展及其批判性比较的批判性分析是本综述下一节的重点。
在单输出传感器、其阵列和连字符读数的发展基础上，利用多变量响应原理的新一代气体传感器正在出现（图6C）。在“经典”（175,176）和最近的综述中回顾了产生多变量响应的多变量传感器和微分析系统。（177-179） 对基于不同转导原理的多变量传感器的最新发展及其批判性比较的批判性分析是本综述下一节的重点。
4 General Principles of Multivariable Sensors
4 多变量传感器的一般原理
ARTICLE SECTIONS
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文章部分J- Abstract
- 1 Introduction
- 2 Diversity of Applications and Requirements for Modern Gas Sensors
- 3 State of the Art of Existing Sensing Concepts
- 4 General Principles of Multivariable Sensors
- 5 Multivariable Nonresonant and Resonant Impedance Sensors
- 6 Electromechanical Multivariable Resonant Sensors
- 7 Multivariable Field-Effect Transistor Sensors
- 8 Multivariable Photonic Resonant Sensors
- 9 Other Multivariable Sensor Technologies
- 10 Design Criteria for Multivariable Sensors
- 11 Benefits of Multivariable Sensors
- 12 Summary and Development Trends of Single-Output and Multivariable Sensors
- Author Information
- Biography
- Acknowledgment
- References
- Cited By
To overcome the insufficient selectivity limitation of existing sensors and sensor arrays and to improve their reliability, a new generation of gas sensors is emerging based on multivariable response principles. Multivariable sensors (also known as intelligent, (180) multiparameter, (181) high-order, (177) or multidimensional signatures (182) sensors, virtual multisensor systems, (183) or virtual sensor arrays (184, 185)) provide several partially or fully independent responses from a sensor. (63, 99, 179, 186) General design criteria for multivariable sensors involve roles of (1) a sensing material with diverse responses to different gases, (2) a multivariable transducer to provide independent outputs and to recognize these different gas responses, and (3) data analytics to provide multianalyte quantitation, rejection of interferences, and drift minimization. The common term “design” reflects a quantitative outcome of creating new materials or devices for particular applications as predicted by existing knowledge. Design of transducers and data analytics tools are two such examples. The complex nature of interactions between the composition, preparation, and end-use conditions of sensing materials often makes difficult their “design”. (187) Instead, “material tuning” is often performed to meet specific needs. (5, 187) Thus, at present, “design” of sensing materials should be viewed as an ultimate future goal rather than the currently available fully developed tool. While new computational tools are decoding the intricate interplay of mechanisms ranging from atomic to macroscopic scales with an increasing accuracy, these tools are not replacing yet the detailed experimental tuning of materials. (188-191) Selectivity and stability of sensing materials are important examples of remaining computational challenges that require experimental validations.
为了克服现有传感器和传感器阵列选择性不足的局限性，提高其可靠性，基于多变量响应原理的新一代气体传感器应运而生。多变量传感器（也称为智能、（180）多参数、（181）高阶、（177）或多维特征（182）传感器、虚拟多传感器系统（183）或虚拟传感器阵列（184、185））提供来自传感器的几个部分或完全独立的响应。(63, 99, 179, 186)多变量传感器的一般设计标准涉及以下角色：（1）对不同气体具有不同响应的传感材料，（2）提供独立输出并识别这些不同气体响应的多变量传感器，以及（3）数据分析，以提供多分析物定量、抑制干扰和漂移最小化。通用术语“设计”反映了现有知识所预测的为特定应用创造新材料或设备的定量结果。传感器和数据分析工具的设计就是这样两个例子。传感材料的组成、制备和最终使用条件之间相互作用的复杂性往往使其“设计”变得困难。（187）相反，通常执行“材料调整”以满足特定需求。(5, 187)因此，目前，传感材料的“设计”应被视为未来的最终目标，而不是目前可用的完全开发的工具。虽然新的计算工具正在以越来越高的精度解码从原子到宏观尺度的机制之间的复杂相互作用，但这些工具还没有取代材料的详细实验调整。 （188-191） 传感材料的选择性和稳定性是需要实验验证的剩余计算挑战的重要例子。
为了克服现有传感器和传感器阵列选择性不足的局限性，提高其可靠性，基于多变量响应原理的新一代气体传感器应运而生。多变量传感器（也称为智能、（180）多参数、（181）高阶、（177）或多维特征（182）传感器、虚拟多传感器系统（183）或虚拟传感器阵列（184、185））提供来自传感器的几个部分或完全独立的响应。(63, 99, 179, 186)多变量传感器的一般设计标准涉及以下角色：（1）对不同气体具有不同响应的传感材料，（2）提供独立输出并识别这些不同气体响应的多变量传感器，以及（3）数据分析，以提供多分析物定量、抑制干扰和漂移最小化。通用术语“设计”反映了现有知识所预测的为特定应用创造新材料或设备的定量结果。传感器和数据分析工具的设计就是这样两个例子。传感材料的组成、制备和最终使用条件之间相互作用的复杂性往往使其“设计”变得困难。（187）相反，通常执行“材料调整”以满足特定需求。(5, 187)因此，目前，传感材料的“设计”应被视为未来的最终目标，而不是目前可用的完全开发的工具。虽然新的计算工具正在以越来越高的精度解码从原子到宏观尺度的机制之间的复杂相互作用，但这些工具还没有取代材料的详细实验调整。 （188-191） 传感材料的选择性和稳定性是需要实验验证的剩余计算挑战的重要例子。
For new multivariable sensors, a subset of sensing materials, already applied to single-output sensors (Table 1), is also of interest because some of these materials have diverse vapor-response mechanisms that can be probed with a multivariable transducer. Further, tools for multivariate analysis of sensing data from individual multivariable sensors can be adapted from those used for sensor arrays (Table 2). Multivariable sensors provide performance capabilities previously unavailable from not only conventional single-output sensors but also from sensor arrays. These new individual sensors quantify individual components in gas mixtures, reject interferences, and have self-correction ability against environmental instabilities. (74, 99, 180, 192-194)
对于新的多变量传感器，已经应用于单输出传感器的传感材料子集（表1）也值得关注，因为其中一些材料具有不同的蒸汽响应机制，可以使用多变量传感器进行探测。此外，用于对来自单个多变量传感器的传感数据进行多变量分析的工具可以与用于传感器阵列的工具相适应（表2）。多变量传感器提供的性能是传统单输出传感器和传感器阵列以前无法提供的。这些新的单个传感器可量化气体混合物中的单个成分，抑制干扰，并具有针对环境不稳定的自我校正能力。(74, 99, 180, 192-194)
对于新的多变量传感器，已经应用于单输出传感器的传感材料子集（表1）也值得关注，因为其中一些材料具有不同的蒸汽响应机制，可以使用多变量传感器进行探测。此外，用于对来自单个多变量传感器的传感数据进行多变量分析的工具可以与用于传感器阵列的工具相适应（表2）。多变量传感器提供的性能是传统单输出传感器和传感器阵列以前无法提供的。这些新的单个传感器可量化气体混合物中的单个成分，抑制干扰，并具有针对环境不稳定的自我校正能力。(74, 99, 180, 192-194)
These capabilities are provided by the number of independent outputs (also known as dispersion, dimensionality, or order) generated by the sensor. A single-output sensor affords a single correlation between a gas concentration and a sensor output and provides a one-dimensional (1-D) response or 1-D dispersion. In such a sensor, gases with known cross-sensitivity produce different response magnitudes but without their discrimination (Figure 7A). Such sensors are valuable to measure known contaminants in the absence of interferences. Sensors with more than one independent output are critical for emerging applications. As the simplest case, Figure 7B depicts the response of a multivariable sensor with two outputs where different gases have their own unique response directions. These independent sensor outputs can be either raw sensor responses or can be weighted contributions of several partially independent outputs. Even this simplest 2-D dispersion allows discrimination between closely related analytes or correction for some environmental interferences. The value of the multivariable sensor increases with its ability to discriminate and quantify gases in the presence of known and unknown interferences and to correct for multiple environmental effects. This increased value is provided by the increased number of independent outputs leading to multidimensional dispersion (Figure 7C). Such value of individual multivariable sensors becomes higher than that of a sensor array not only because of similar (180, 195, 196) or better (99) short-term performance over sensor arrays but also because of an improved capability for long-term stability.
这些功能由传感器产生的独立输出数量（也称为色散、维数或阶数）提供。单输出传感器提供气体浓度和传感器输出之间的单一相关性，并提供一维 （1-D） 响应或一维色散。在这种传感器中，具有已知交叉灵敏度的气体产生不同的响应幅度，但没有区分（图7A）。这种传感器对于在没有干扰的情况下测量已知污染物很有价值。具有多个独立输出的传感器对于新兴应用至关重要。作为最简单的情况，图7B描述了具有两个输出的多变量传感器的响应，其中不同的气体具有自己独特的响应方向。这些独立的传感器输出可以是原始传感器响应，也可以是多个部分独立输出的加权贡献。即使是这种最简单的二维分散，也可以区分密切相关的分析物或校正某些环境干扰。多变量传感器的价值随着其在存在已知和未知干扰的情况下区分和量化气体以及校正多种环境影响的能力而增加。这种增加的值是由导致多维色散的独立输出数量的增加提供的（图7C）。单个多变量传感器的这种值变得高于传感器阵列的值，这不仅是因为与传感器阵列相似（180,195,196）或更好（99）的短期性能，而且还因为长期稳定性的能力有所提高。
这些功能由传感器产生的独立输出数量（也称为色散、维数或阶数）提供。单输出传感器提供气体浓度和传感器输出之间的单一相关性，并提供一维 （1-D） 响应或一维色散。在这种传感器中，具有已知交叉灵敏度的气体产生不同的响应幅度，但没有区分（图7A）。这种传感器对于在没有干扰的情况下测量已知污染物很有价值。具有多个独立输出的传感器对于新兴应用至关重要。作为最简单的情况，图7B描述了具有两个输出的多变量传感器的响应，其中不同的气体具有自己独特的响应方向。这些独立的传感器输出可以是原始传感器响应，也可以是多个部分独立输出的加权贡献。即使是这种最简单的二维分散，也可以区分密切相关的分析物或校正某些环境干扰。多变量传感器的价值随着其在存在已知和未知干扰的情况下区分和量化气体以及校正多种环境影响的能力而增加。这种增加的值是由导致多维色散的独立输出数量的增加提供的（图7C）。单个多变量传感器的这种值变得高于传感器阵列的值，这不仅是因为与传感器阵列相似（180,195,196）或更好（99）的短期性能，而且还因为长期稳定性的能力有所提高。
Figure 7 图7
Figure 7. Importance of sensor response dispersion for reliable performance. (A) 1-D dispersion of a single-output sensor, sensor affords a single correlation between a gas concentration and sensor output. Gases with known cross-sensitivity have different response magnitudes without their discrimination. (B) 2-D dispersion of a multivariable sensor with two independent outputs; different gases have their own unique response directions, affording the possibility for correction for some environmental interferences. (C) 3-D dispersion of a multivariable sensor to monitor multiple gases in the presence of known and unknown interferences and closely related gases of different classes and to correct for multiple environmental effects.
图7.传感器响应色散对可靠性能的重要性。（A）单输出传感器的一维色散，传感器提供气体浓度和传感器输出之间的单一相关性。具有已知交叉敏感性的气体具有不同的响应幅度，而无需区分。（B） 具有两个独立输出的多变量传感器的二维色散;不同的气体有自己独特的响应方向，为校正某些环境干扰提供了可能性。（C） 多变量传感器的三维色散，用于监测存在已知和未知干扰的多种气体以及不同类别的密切相关气体，并校正多种环境影响。
In this Review, dispersion of the reported multivariable sensors was determined based on results of multivariate analysis of their individual outputs. The criterion for reporting dispersion of a multivariable sensor was its highest reported dispersion at which the sensor demonstrated the consistent diverse vapor-dependent responses. The most widely implemented multivariate analysis technique in multivariable sensors is PCA followed by DA, ANN, and other techniques summarized in Table 2. To illustrate the PCA approach, performance of a multivariable sensor has been simulated and processed using PCA as shown in Figure 8. This simulated sensor had a “spectrum” across 150 variables (a.k.a. dimensions such as frequencies or wavelengths) with an added random noise (Figure 8A). Three environmental effects (e.g., analyte vapor, humidity, and temperature) were assumed to change the peak height, peak position, and peak width of the spectrum (Figure 8A). Three levels of each of the effects were simulated (shown in Figure 8B), with three replicates per each level (not shown for simplicity). From the raw responses with a total of 30 samples of spectra (initial position, three effects at three levels, n = 3 for each), a PCA classification model was built. Several outputs from a PCA model are important for understanding and visualization of spectral changes in the sensor. One output is a scores plot that visualizes relations between measured spectra by presenting principal components (PCs) against each other or as a function of experimental time. A PC1 vs PC2 plot in Figure 8C illustrates that the contributions from the first two PCs (52.14% and 42.54%, respectively) did not cover 100% of the variance produced by the sensor. Thus, Figure 8D depicts a 3-D plot of PC1 vs PC2 vs PC3 illustrating that PC3 also correlated well with the three types of environmental effects. Another output is a signal-to-noise (S/N) plot of each PC in the model that determines which PCs have low S/N. Figure 8E depicts that the built PCA model had three PCs that had S/N ≫ 3. The third output is the loadings plot that reveals contributions of each variable to different PCs. Figure 8F depicts that loadings of the first three PCs had different spectral shapes.
在本综述中，报告的多变量传感器的离散度是根据其各自输出的多变量分析结果确定的。报告多变量传感器色散的标准是其报告的最高色散度，在该色散度下，传感器表现出一致的多样化蒸汽依赖性响应。在多变量传感器中应用最广泛的多变量分析技术是PCA，其次是DA、ANN和其他技术，如表2所示。为了说明PCA方法，使用PCA对多变量传感器的性能进行了仿真和处理，如图8所示。该模拟传感器具有跨越 150 个变量（也称为频率或波长等尺寸）的“频谱”，并增加了随机噪声（图 8A）。假设三种环境效应（例如，分析物蒸气、湿度和温度）会改变光谱的峰高、峰位置和峰宽（图8A）。模拟了每个效应的三个水平（如图8B所示），每个水平有三个重复（为简单起见，未显示）。从总共 30 个光谱样本的原始响应（初始位置，三个水平的三个效应，每个效应 n = 3）中，构建了 PCA 分类模型。PCA模型的几个输出对于理解和可视化传感器中的光谱变化非常重要。一个输出是分数图，它通过呈现主成分 （PC） 彼此之间或作为实验时间的函数来可视化测量光谱之间的关系。图8C中的PC 1 与PC 2 关系图表明，前两台PC的贡献（分别为52.14%和42.54%）并未覆盖传感器产生的100%方差。 因此，图8D描绘了 PC 1 vs PC 2 vs PC 3 的 3D 图，说明 PC 3 也与三种类型的环境影响密切相关。另一个输出是模型中每台 PC 的信噪比 （S/N） 图，用于确定哪些 PC 的信噪比较低。图 8E 描述了构建的 PCA 模型有三台 PC 的信噪比为 3≫。第三个输出是载荷图，它揭示了每个变量对不同PC的贡献。 图8F描述了前三台PC的载荷具有不同的光谱形状。
在本综述中，报告的多变量传感器的离散度是根据其各自输出的多变量分析结果确定的。报告多变量传感器色散的标准是其报告的最高色散度，在该色散度下，传感器表现出一致的多样化蒸汽依赖性响应。在多变量传感器中应用最广泛的多变量分析技术是PCA，其次是DA、ANN和其他技术，如表2所示。为了说明PCA方法，使用PCA对多变量传感器的性能进行了仿真和处理，如图8所示。该模拟传感器具有跨越 150 个变量（也称为频率或波长等尺寸）的“频谱”，并增加了随机噪声（图 8A）。假设三种环境效应（例如，分析物蒸气、湿度和温度）会改变光谱的峰高、峰位置和峰宽（图8A）。模拟了每个效应的三个水平（如图8B所示），每个水平有三个重复（为简单起见，未显示）。从总共 30 个光谱样本的原始响应（初始位置，三个水平的三个效应，每个效应 n = 3）中，构建了 PCA 分类模型。PCA模型的几个输出对于理解和可视化传感器中的光谱变化非常重要。一个输出是分数图，它通过呈现主成分 （PC） 彼此之间或作为实验时间的函数来可视化测量光谱之间的关系。图8C中的PC 1 与PC 2 关系图表明，前两台PC的贡献（分别为52.14%和42.54%）并未覆盖传感器产生的100%方差。 因此，图8D描绘了 PC 1 vs PC 2 vs PC 3 的 3D 图，说明 PC 3 也与三种类型的环境影响密切相关。另一个输出是模型中每台 PC 的信噪比 （S/N） 图，用于确定哪些 PC 的信噪比较低。图 8E 描述了构建的 PCA 模型有三台 PC 的信噪比为 3≫。第三个输出是载荷图，它揭示了每个变量对不同PC的贡献。 图8F描述了前三台PC的载荷具有不同的光谱形状。
Figure 8 图8
Figure 8. Illustration of typical PCA results from a computer-simulated multivariable sensor. (A) “Spectrum” of a sensor with indicated changes in peak height, peak position, and peak width upon application of simulated environmental effects. (B) Three levels of spectral changes in peak height, peak position, and peak width. (C, D) Visualization of relations between measured spectra by presenting PCA scores plots of PC1 vs PC2 and PC1 vs PC2 vs PC3, respectively. (E) Plot of the signal-to-noise (S/N) of each PC in the model. (F) Loadings plot that depicts contributions of each variable to different PCs.
图8.计算机模拟多变量传感器的典型 PCA 结果图示。（A） 传感器的“光谱”，在应用模拟环境效应时，峰高、峰位置和峰宽会发生变化。（B） 峰高、峰位和峰宽三个层次的光谱变化。（C、D）通过分别呈现 PC 与 PC 1 2 和 PC 1 与 PC 与 PC 2 3 的 PCA 分数图，可视化测量光谱之间的关系。（E） 模型中每台 PC 的信噪比 （S/N） 图。（F） 描述每个变量对不同 PC 的贡献的加载图。
5 Multivariable Nonresonant and Resonant Impedance Sensors
5 个多变量非谐振和谐振阻抗传感器
ARTICLE SECTIONS
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文章部分J- Abstract
- 1 Introduction
- 2 Diversity of Applications and Requirements for Modern Gas Sensors
- 3 State of the Art of Existing Sensing Concepts
- 4 General Principles of Multivariable Sensors
- 5 Multivariable Nonresonant and Resonant Impedance Sensors
- 6 Electromechanical Multivariable Resonant Sensors
- 7 Multivariable Field-Effect Transistor Sensors
- 8 Multivariable Photonic Resonant Sensors
- 9 Other Multivariable Sensor Technologies
- 10 Design Criteria for Multivariable Sensors
- 11 Benefits of Multivariable Sensors
- 12 Summary and Development Trends of Single-Output and Multivariable Sensors
- Author Information
- Biography
- Acknowledgment
- References
- Cited By
Multivariable impedance sensors typically measure vapor-modulated changes of resistance R and capacitance C of a sensing structure in nonresonant and resonant configurations. Measurements of R and C in a nonresonant configuration can be performed by using an electrode RC circuit structure (see Figure 9A) that incorporates a sensing film. (197-199) Adding an inductor L to such an electrical circuit provides a resistor–inductor–capacitor (RLC) resonator (see Figure 9B), where changes in R and C can be measured in a resonant circuit configuration. (200) Sensor-excitation conditions also can increase dispersion of sensor response. (201, 202) The advantage of resonators is sometimes a higher sensitivity over nonresonant structures. (203) Resonant response can be the resonance impedance spectrum (Figure 9C). Measurements can be done of the real part Zre and imaginary part Zim of resonance impedance, and representative parameters for multivariate analysis can be determined such as frequency Fp and magnitude Zp of the real part of the resonance impedance spectrum, the resonant F1 and antiresonant F2 frequencies of the imaginary part of the resonance impedance spectrum, and their impedance magnitudes Z1 and Z2, respectively. (200, 204)
多变量阻抗传感器通常测量非谐振和谐振配置中传感结构的电阻 R 和电容 C 的蒸汽调制变化。使用包含传感膜的电极RC电路结构（见图9A）可以对非谐振配置中的R和C进行测量。（197-199） 在这种电路中增加一个电感器L，可以得到一个电阻-电感器-电容器（RLC）谐振器（见图9B），其中R和C的变化可以在谐振电路配置中测量。（200） 传感器激励条件也会增加传感器响应的分散性。(201, 202)谐振器的优点有时是比非谐振结构具有更高的灵敏度。（203）谐振响应可以是谐振阻抗谱（图9C）。可以测量谐振阻抗的实部Z re 和虚部Z im ，并可以确定多变量分析的代表性参数，例如谐振阻抗谱实部的频率F p 和幅值Z p ，谐振阻抗谱虚部的谐振F 1 和反谐振F 2 频率， 以及它们的阻抗幅度分别为 Z 1 和 Z 2 。(200, 204)
多变量阻抗传感器通常测量非谐振和谐振配置中传感结构的电阻 R 和电容 C 的蒸汽调制变化。使用包含传感膜的电极RC电路结构（见图9A）可以对非谐振配置中的R和C进行测量。（197-199） 在这种电路中增加一个电感器L，可以得到一个电阻-电感器-电容器（RLC）谐振器（见图9B），其中R和C的变化可以在谐振电路配置中测量。（200） 传感器激励条件也会增加传感器响应的分散性。(201, 202)谐振器的优点有时是比非谐振结构具有更高的灵敏度。（203）谐振响应可以是谐振阻抗谱（图9C）。可以测量谐振阻抗的实部Z re 和虚部Z im ，并可以确定多变量分析的代表性参数，例如谐振阻抗谱实部的频率F p 和幅值Z p ，谐振阻抗谱虚部的谐振F 1 和反谐振F 2 频率， 以及它们的阻抗幅度分别为 Z 1 和 Z 2 。(200, 204)
Figure 9 图9
Figure 9. Design and operation of multivariable impedance vapor sensors. Simplified equivalent circuits of (A) nonresonant and (B) resonant sensor configurations to probe vapor-modulated changes of resistance Rs and capacitance Cs of a sensing material. (C) Resonance impedance spectrum (real part Zre and imaginary part Zim of resonance impedance) and representative parameters for multivariate analysis: frequency position Fp and magnitude Zp of the real part of the resonance impedance spectrum, the resonant F1 and antiresonant F2 frequencies of the imaginary part of the resonance impedance spectrum, and their impedance magnitudes Z1 and Z2, respectively.
To provide useful impedance response that will have diversity for different gases, the sensors should have the ability to change independently measured real and imaginary impedance values. These independent changes can originate from several types of contributions of the sensing structure. One type of contribution is the change in R and C from the bulk of the sensing material itself that is related to changes in the complex permittivity of the sensing material that can be correlated to a single or multiple analytes of interest and can provide correction of environmental effects. (194, 205) The real part of the complex permittivity of the sensing material is its “dielectric constant”. The imaginary part of the complex permittivity of the sensing material is its “dielectric loss factor” and is directly proportional to the conductivity of the sensing material. In impedance sensors, measurements can be done at a single (206) or at multiple frequencies. (207-210) While measurements at a single frequency provide a useful sensor, analysis at multiple frequencies could achieve an enhanced selectivity.
The change in R and C of portions of the sensing structure besides the bulk of the sensing material can also contribute to sensor response. These contributions can originate from several independent regions of the film/transducer system such as contact resistance and capacitance of the film/electrode interface, surface resistance and capacitance, and substrate/film interface resistance and capacitance (211) as visualized in Figure 10. As an example, parts A and B of Figure 11 show transmission electron microscope images of film/transducer interface, respectively, without and with a contact layer engineered to enhance sensor selectivity via an additional vapor-responsive RC circuit structure.
Figure 10
Figure 10. Details of the sensing region where a sensing material is applied onto the sensor electrodes. Effects of the sensing film are pronounced in resistance and capacitance related to the film width between electrodes, film thickness, contact resistance and capacitance, surface resistance and capacitance, and substrate/film interface resistance and capacitance.
Figure 11
Figure 11. Transmission electron microscope images of film/transducer interface without (A) and with (B) an engineered contact layer for the enhancement of sensor selectivity.
Impedance gas sensing was first demonstrated decades ago, (195, 212-215) including impedance measurements in gas mixtures, (180, 216) and has been the foundation for the modern RC and RLC sensor developments. These sensors can be probed using analyzers that can measure multiple output parameters from a single sensor. (217) Besides operating in the radio frequency (MHz) frequency range with RLC resonant sensors, (200) such sensors also have been demonstrated in the microwave (GHz) (218-220) frequency ranges. Numerous portable and single-chip analyzers have been developed to be applicable for these measurements. (221-233)
To date, multivariable impedance sensors are the most broadly explored multivariable sensors. They have been demonstrated with a wide range of sensing materials that exhibit independent or partially independent changes in their complex permittivity for discrimination between multiple gases, rejection of interferences, and correction for environmental effects. In this section, several diverse types of materials are analyzed to illustrate the power of multivariable sensing using electrical nonresonant and resonant impedance sensors. The most studied sensing materials include dielectric (198, 201, 202, 205, 215, 220, 234) and conjugated (192, 195, 204, 235-237) polymers, macrocycles, (215, 238) metal oxides, (182, 206, 239-241) carbon allotropes, (242, 243) and ligand-capped metal nanoparticles. (178, 192, 201, 207, 244) Less-explored materials are transition metal dichalcogenide monolayers MX2, with M being a transition metal atom (e.g., Mo, W) and X being a chalcogen atom (e.g., S, Se, Te). (245)
Dielectric Polymers
Dielectric polymers exhibit gas-sensing mechanisms such as dispersion, polarizability, dipolarity, basicity, acidity, and hydrogen-bonding interactions. (76) In single-output sensors, measurements are performed with capacitance readout (246, 247) unless these polymers are formulated with conducting nanoparticles to measure the change in sensor conductivity. (248) Such sensors have known insufficient selectivity; thus, they have been assembled into classic sensor arrays. (234, 249) Several reviews analyze performance of dielectric polymers in gas sensing. (76, 250)
In an important initial study using impedance measurements, dielectric polymers were deposited as films onto interdigital electrodes and exposed to several organic vapors. (215) While absorbed vapors had only negligible effect on the sensing film conductivity G, sensor resistance R exhibited significant changes due to the relation to sensor capacitance C as R = G/(G2 + (2πfC)2) where f was the measurement frequency. Following that initial study, polymer-coated nonresonant (198, 234) and RLC resonant sensors (201, 202, 205, 220) have been demonstrated for gas sensing. Examples of dielectric polymers that have been explored with multivariable RC and RLC sensors include ethylcellulose, poly(ethyl acrylate), poly(etherurethane), poly(vinyl acetate), cyanopropylmethylphenylmethyl silicone, dicyanoallyl silicone, and polysiloxane with pendant hexafluoro-2-propanol groups. (201, 202, 205, 215, 220)
Poly(etherurethane) has been used most extensively on RLC resonant transducers and has demonstrated important advancements in multivariable sensing using analysis of resonant spectra shown in Figure 9C. Diverse volatiles were discriminated with 2-D dispersion of the data shown by the PCA scores plot in Figure 12 (201) with PCA responses roughly related to vapor dielectric constant. Self-correction against fluctuations of ambient temperature was demonstrated (Figure 13) (194, 251) by taking advantage of different temperature- and gas-induced effects on the equivalent circuit components of the sensor (dielectric sensor substrate, metal sensor coil, dielectric sensing film, and semiconductor memory chip). Such an approach will be attractive in applications where temperature stabilization of a gas sensor or addition of auxiliary temperature or uncoated reference sensors is prohibitive. When RLC sensors were tested with relatively high concentrations of vapors, 3-D sensor dispersion was achieved even using only three model vapors (water, toluene, and tetrahydrofuran) as illustrated in Figure 14. (201) The PC3 contribution of that sensor was 0.01% but was correlated with concentrations of vapors. Another RLC sensor was based on a conventional flexible passive radio frequency identification (RFID) tag with an integrated circuit memory chip and its antenna inlay laminated with poly(etherurethane) film. Using four vapors (toluene, acetone, ethanol, and water), this sensor had 3-D dispersion and demonstrated a strong PC3 contribution of 13% as shown in Figure 15A (252) due to the carefully selected sensor-excitation conditions. Using a roll-to-roll manufacturing process, ∼5000 flexible RFID sensors were made (Figure 15B). (63) Binary and ternary mixtures of model vapors were quantified using RLC sensors with poly(etherurethane) sensing films. (201)
Figure 12
Figure 12. 2-D dispersion of a multivariable RLC resonant sensor with poly(etherurethane) sensing film presented as PCA scores plot in discrimination of eight volatiles at their single concentrations. (201) Dielectric constants of respective solvents are shown in parentheses.
Figure 13
Figure 13. Response of the developed multivariable resonant RLC sensor to various concentrations of water vapor at variable temperatures. (A) PCA scores plot. (B) Actual vs predicted values of water vapor concentrations at four different temperatures. Reprinted with permission from ref 194. Copyright 2013 Elsevier.
Figure 14
Figure 14. 3-D dispersion of a multivariable RLC resonant sensor with poly(etherurethane) sensing film presented as PCA scores plots in discrimination of three volatiles at their various concentrations. (201) Dielectric constants of respective solvents are shown in parentheses.
Figure 15
Figure 15. 3-D dispersion of a multivariable RLC resonant sensor with poly(etherurethane) sensing film presented as PCA scores plot and an example of manufactured sensors. (A) 3-D sensor dispersion in discrimination of four volatiles at their various concentrations. Dielectric constants of respective solvents are shown in parentheses. (B) Example of roll-to-roll manufactured sensors on a flexible substrate. Reprinted with permission from ref 63. Copyright 2012 The Royal Society of Chemistry.
Resonant RLC sensors also can be evaluated by measurements of response delay, resonant frequency, and other parameters. (253-255) In recent multivariable sensors operating in the microwave range, measurements of response delay were combined with resonant frequency and response amplitude. (220) Response signatures of sensors coated with cyanopropylmethylphenylmethyl silicone and polysiloxane with pendant hexafluoro-2-propanol groups are illustrated in Figure 16 as scores plots of PCA models. These results illustrate 2-D dispersion of these sensors where the chosen polymer modulates the selectivity of the sensor and its contributions to PC1 and PC2.
Figure 16
Figure 16. PCA scores plots illustrating 2-D dispersion of multivariable RLC resonant sensors based on measurements of response delay, resonant frequency, and response amplitude. Sensing films: (A) cyanopropyl methyl phenylmethyl silicone and (B) polysiloxane with pendant hexafluoro-2-propanol groups. Data adapted and reproduced with permission from ref 220. Copyright 2015 Elsevier.
Conjugated Polymers
Conjugated polymers (also known as conducting polymers (256, 257) or intrinsically conducting polymers (258)) exhibit several mechanisms of gas response including changes in density and charge carrier mobility, polymer swelling, and conformational transitions of polymer chains. (77, 78) Sensors with single-output measurements of resistance (259, 260) or capacitance (261) of conjugated polymers have known insufficient selectivity; thus, they have been assembled into classic sensor arrays. (259, 260) Several reviews analyze applications of conjugated polymers in single-output sensors and their arrays. (256-258, 262)
In one important early study, impedance measurements at relatively low frequencies (20 Hz–10 kHz) were utilized to explore changes of relative permittivity of a “classic” conjugated polymer such as polypyrrole upon exposure to different volatiles (methanol, acetone, ethyl acetate, and ethanol). (235) The patterns of R and C responses to these volatiles were different and comparable to those produced using conventional multisensor arrays. Impedance measurements were also explored at high frequencies in resonant sensor configurations using polypyrrole (195) and polyaniline. (196) In these sensors, the dissipation factor was an indicator of the change in dipole–dipole interactions upon sorption of vapors into polymers. Figure 17A shows the dissipation factor vs frequency response of polypyrrole to methanol, ethyl acetate, and acetone vapors. (195) A specific frequency of the sensor dissipation factor was related to vapor type, while the response magnitude was proportional to vapor concentration. It was suggested that these specific frequency responses may be correlated to the permittivity of the polymer film. This technique was further applied to analyze mixtures of vapors (Figure 17B) and was coupled with ANN to determine concentrations of individual vapors in binary, tertiary, and quaternary mixtures. (180)
Figure 17
Figure 17. Dissipation factor measurements using multivariable RLC resonant sensors with conjugated polymers. (A) Response to individual vapors of methanol, acetone, and ethyl acetate. (B) Response to individual vapors of acetone and methanol and their binary mixtures. (A) Reprinted with permission from ref 195. Copyright 1995 Institute of Physics. (B) Reprinted with permission from ref 180. Copyright 1997 Elsevier.
Following these early experiments, conjugated polymers have been explored with recently developed passive RLC resonator-based RFID sensors. (192, 204, 236) For detection of diverse volatiles using these RFID sensors, several conjugated polymers have been utilized such as poly(3,4-ethylenedioxythiophene), polyaniline, poly(fluorene)diphenylpropane, and others, (192, 204, 236, 237) demonstrating 2-D sensor dispersion.
Macrocycles
Macrocycles (e.g., metalloporphyrins and metallophthalocyanines) exhibit gas-sensing ability by π-stacking of gas molecules into organized layers of the flat macrocycles or by gas coordination to the metal center without the cavity inclusion. Mechanisms of gas response of these materials include hydrogen bonding, polarization, polarity interactions, metal center coordination interactions, and molecular arrangements. (79, 80) Performance of porphyrins and cyanines in single-output gas sensing has been recently reviewed. (263)
Impedance sensing was investigated for detection of organic vapors using a nonconductive film of tetrakis-t-butyl phthalocyaninatonickel deposited onto interdigital electrodes. (215) Similar to other tested nonconductive films, absorbed vapors had only negligible effect on the conductivity of the metallophthalocyanine sensing film, but both sensor resistance and capacitance had significant changes when exposed to model organic solvent vapors (dichloromethane, chloroform, trichloroethene, toluene, and ethanol), providing the response pattern illustrated in Figure 18A. (215)
Figure 18
Figure 18. Applications of metallophthalocyanines for multivariable vapor sensing. (A) Diversity of resistance and capacitance responses obtained from nonresonant impedance measurements of tetrakis-t-butyl phthalocyaninatonickel film. (215) (B) Diversity of dissipation spectra obtained from resonant measurements of cobalt phthalocyanine film. (238) (A) Reprinted with permission from ref 215. Copyright 1996 Elsevier. (B) Reprinted with permission from ref 238. Copyright 2006 American Institute of Physics.
Impedance sensing has been further used to identify vapors using resonant sensor structures coated with metallophthalocyanine films. (238) Three model vapors (methanol, ethanol, and isopropanol) were differentiated using a cobalt phthalocyanine sensing material based on the frequency shifts due to the charge, dielectric, and dipolar relaxation behavior of the sensing material. The spectra of the sensor exposed to the three alcohols at their saturation concentrations are shown in Figure 18B. (238)
Metal Oxides
Metal oxides have different gas-response mechanisms (e.g., physisorption, chemisorption, surface defects, and bulk defects) when such sensors operate at temperatures ranging from ambient to ∼1000 °C and utilize different types of metal oxides and dopants. (85-87) Examples of metal oxides include single-metal oxides (e.g., SnO2, ZnO, CuO, CoO, TiO2, ZrO2, CeO2, WO3, MoO3, In2O3, and Ga2O3), perovskite oxide structures with two differently sized cations (e.g., SrTiO3, CaTiO3, BaTiO3, LaFeO3, LaCoO3, and SmFeO3), and mixed metal oxide compositions (e.g., CuO-BaTiO3 and ZnO-WO3). (87, 124, 264-266) The majority of metal oxides in gas sensing are n-type oxide semiconductors, with only a handful of materials that are p-type oxide semiconductors (e.g., NiO, CuO, Cr2O3, Co3O4, and Mn2O4). (267) The junctions between p- and n-type semiconductors are also attractive for gas sensing based on their work functions, bandgaps, and electron affinities. (267)
Historically, gas response in MOS sensors has been measured as the change in sensor resistance. (268) There are also examples of capacitance measurements in metal oxides ranging from single-metal oxides (e.g., In2O3 and SnO2) to mixed metal oxide compositions (e.g., CuO-BaTiO3 and ZnO-WO3). (269-271) Sensors based on traditional single-output measurements of resistance or capacitance of metal oxides have known insufficient selectivity; as a result, they have been assembled into classic sensor arrays as recently reviewed. (148)
Different techniques to improve the selectivities of individual MOS sensors have been explored. One such technique utilized a carefully designed temperature modulation of a metal oxide sensing film to take advantage of different mechanisms of gas response of metal oxides and their gas selectivity at different temperatures. (239, 272-277) For example, this approach provided an impressive ability to resolve numerous odors with a single sensor using a conventional resistance readout but by rapidly (<10 s) cycling a sensor through multiple temperatures ranging from ∼50 to ∼480 °C. (239) The response of a SnO2 sensor at multiple temperatures was analyzed by using a linear DA, demonstrating the ability to resolve different odors in a 3-D space of the built model (Figure 19). (276)
Figure 19
Figure 19. Gas selectivity of a conventional SnO2 sensing film by temperature modulation demonstrated using a linear discrimination analysis (LDA) plot for hydrogen cyanide (HCN) discrimination from a variety of backgrounds containing HCN and eight types of interfering species (1–8). Reprinted with permission from ref 276. Copyright 2007 Elsevier.
Impedance measurements of metal oxide sensing films were introduced two decades ago, resulting in improvement of gas selectivity. (240) Recently, to explore the opportunities to improve selectivity of Pt-doped CeO2 nanofibers, single-frequency impedance measurements were performed and compared with conventional resistance measurements. The comparison was done by detecting CO reducing gas and testing O2, CO2, NO, and SO2 as interferences. (206) Resistive response to CO had a significant interference from O2 (Figure 20A). Impedance measurements at 100 kHz eliminated this interference effect (Figure 20B).
Figure 20
Figure 20. Gas selectivity of Pt-doped CeO2 nanofibers to CO using (A) conventional resistance and (B) single-frequency impedance measurements at 100 kHz. Reprinted with permission from ref 206. Copyright 2013 Elsevier.
When resistance and capacitance measurements were combined, 2-D responses were obtained using a sensor based on In2O3 single-metal oxide upon exposure to five gases such as NO2, NH3, CO, NO, and acetone at their single concentrations. (182) The time-dependent conductance vs capacitance plots provided the ability to discriminate between individual gases (Figure 21). The ability to discriminate between mixtures of gases was also explored using mixtures of NO2 and NH3 at different ratios. It was found that responses from mixtures did not correspond to a simple addition of responses according to their gas-phase composition and were much closer to that for the NO2 alone, possibly due to different adsorption coefficients of NO2 and NH3 molecules. Further, an addition of a surface work function measurements provided 3-D responses achieved for individual gases. It was also suggested that a 4-D response could be possible by adding adsorption-induced stress detection, which has been widely used for microcantilevers.
Figure 21
Figure 21. Discrimination between individual gases using an In2O3 sensing material coupled with capacitance and conductance measurements at 1 kHz upon exposure to NO2, NH3, CO, NO, and acetone at their single concentrations. Reprinted with permission from ref 182. Copyright 2011 Elsevier.
Using a Pd-doped SnO2, a 2-D response from an individual sensor was obtained by measurements of changes in properties of a resonant RLC sensor upon exposure to five gases such as hydrogen peroxide, ethanolamine, water, chlorine dioxide, and ammonia at their multiple concentrations. (241) As shown in Figure 22, the PCA scores plot produced from responses of a single sensor demonstrated the sensor ability to discriminate between five gases based on the number of their valence electrons.
Figure 22
Figure 22. Discrimination between individual gases using a Pd-doped SnO2 sensing material coupled with resonant impedance measurements followed by PCA upon exposure to hydrogen peroxide, ethanolamine, water, chlorine dioxide, and ammonia at their various concentrations. The sensor discriminated between five gases based on the number of their valence electrons as shown in parentheses. (241)
Carbon Allotropes
Carbon allotropes (e.g., amorphous carbon, fullerenes, carbon nanotubes, graphene, and graphite) can act either as a main component in the sensing film to facilitate analyte recognition and provide signal transduction or as an additive in the sensing film matrix to provide signal transduction. Sensors based on traditional single-output measurements of resistance or capacitance of carbon allotropes have known insufficient selectivity; as a result, they have been assembled into classic sensor arrays. (278) Recent reviews summarize single-output sensors and arrays based on carbon allotropes. (279-286)
Carbon allotropes have been explored for multivariable sensing because they can exhibit at least partially independent changes in their different electrical properties at room temperature. Simultaneous measurements of capacitance and conductance of single-walled carbon nanotubes (SWCNTs) grown by chemical vapor deposition and exposed to diverse vapors demonstrated the existence of two distinct physiochemical properties of adsorbed vapors such as charge transfer and polarizability. (242) The ratio of conductance to capacitance response was found to be a concentration-independent intrinsic property of a specific gas, useful as a parameter for gas identification (Figure 23).
Figure 23
Figure 23. Ratio of conductance to capacitance response of SWCNTs grown by chemical vapor deposition and exposed to diverse individual vapors is a concentration-independent intrinsic property of a specific gas, useful as a parameter for gas identification. Data adapted and reproduced with permission from ref 242. Copyright 2005 American Chemical Society.
Following these initial observations, application of SWCNTs onto RLC resonators provided a 2-D dispersion of individual sensors. In one study, SWCNTs functionalized with carboxylic acid were used for sensing of model vapors such as water, methane, and toluene, selected as examples of different polarities and types of SWCNT–vapor interactions. The sensor resonant spectra were processed as described in Figure 9C. All volatiles were discriminated by using only two PCs in a PCA scores plot (Figure 24).
Figure 24
Figure 24. PCA scores plot of an RLC sensor with SWCNTs functionalized with carboxylic acid upon exposure to varying concentrations of water, methane, and toluene vapors.
In another study that involved SWCNTs functionalized with polyaminobenzenesulfonic acid, other vapors were selected such as water, acetonitrile, dichloromethane, and chloroform. These vapors were selected as examples of different polarities of SWCNT–vapor interactions. Results of PCA illustrated that all four volatiles were discriminated by generating 2-D response dispersion (Figure 25). (243)
Figure 25
Figure 25. PCA scores plot of an RLC sensor with SWCNTs functionalized with polyaminobenzenesulfonic acid upon exposure to varying concentrations of water, acetonitrile, dichloromethane, and chloroform vapors.
Ligand-Capped Metal Nanoparticles
Ligand-capped metal nanoparticles (also known as colloidal metal–insulator–metal ensembles (287) or monolayer-protected metal nanoparticles (288)) have the gas-sensing mechanisms that involve electron tunneling between metal cores through the dielectric ligand shell and charge hopping along the shell. Sensor response diversity can be tuned by designing different ligands (e.g., organothiol derivatives, dendrimers, organoamines, and mercaptocarboxylic acids) surrounding metallic cores. (289-295) Ligands can be broadly divided into two classes, with soft and rigid linkers. Soft linkers change their length as a function of the amount of sorbed vapor modulating film resistance. Rigid linkers restrain swelling of sensing films and boost effects of analyte-dependent changes of the film dielectric constant. (296-298) Several recent reviews detail conductivity measurements using ligand-capped metal nanoparticles. (283, 299-301)
Although chemiresistor measurements are very attractive with ligand-capped metal nanoparticles because of simplicity, (287) other transduction modalities have also been implemented such as capacitance, impedance, and RLC resonators, (192, 201, 207, 244) as well as gravimetric detection (see section 6) and optical detection (see section 8).
In a recent study, resistance and capacitance responses of metal nanoparticles capped with an organic (2-mercapto-benzylalcoholthiol) ligand were compared using impedance spectroscopy measurements. (207) As expected, (178) humidity effects were more pronounced in capacitance vs resistance responses, which is especially important to take into account in real-world applications. The applicability of biological capping ligands to gold nanoparticles for selective vapor sensing was demonstrated using gold nanoparticles capped with a peptide AYSSGAPPMPPF deposited onto an RLC resonant sensor. (244) As model toxic vapors and chemical warfare agent simulants, acetonitrile, dichloromethane, and methyl salicylate were used. The PCA scores plot demonstrated 2-D dispersion with almost opposite response directions to dichloromethane and methyl salicylate vapors even though they have very similar dielectric constants (i.e., εr = 9.1 and 9.0, respectively). A possible explanation of this effect may be that methyl salicylate is more bulky than dichloromethane, resulting in different rigidity of the linker.
Discrimination of vapors of the first nine linear alcohols of their homologous series and water was further accomplished with Au nanoparticles capped with a 1-octanethiol ligand deposited onto a RLC resonant sensor (Figure 26). (201) Detection of these closely related alcohol vapors is not straightforward even using gas chromatography and sensor arrays. (302) The sensor was exposed to four increasing concentrations of 10 vapors each starting from water, to methanol, ethanol, 1-propanol, 1-butanol, 1-pentanol, 1-hexanol, 1-heptanol, 1-octanol, and 1-nonanol as vapors 1–10. The single sensor provided several diverse responses Fp, F1, F2, and Zp that are illustrated in Figure 26A–D. The red dotted lines in Figure 26A–D depict the patterns of each of the responses of the multivariable sensor to 10 vapors. The knowledge of gas-induced effects on permittivity (192, 201, 207, 244) and conductivity (287) of ligand-capped metal nanoparticles was important motivation to visualize the relation between raw sensor responses. Figure 26E depicts the plot of Zp vs Fp that was chosen because sensor response Zp was known to be correlated with the resistance of ligand-capped Au nanoparticles sensing film while Fp was correlated with its capacitance. This plot of raw responses of Zp vs Fp illustrates an excellent ability of the sensor to discriminate between nine linear alcohols of their homologous series and water. Interestingly the raw Fp response had minimal effect from 1-nonanol (vapor 10, Figure 26A), while the raw Zp response had minimal effect from methanol (vapor 2, Figure 26D). Thus, the plot of Zp vs Fp had respective horizontal and vertical responses for vapors 10 and 2 (Figure 26E). A PCA classification model was further developed using Fp, F1, F2, and Zp responses. A scores plot of the first two PCs (Figure 26F) demonstrated an excellent general resemblance with the plot of raw responses Zp vs Fp (Figure 26E), confirming the vapor-discrimination power of this sensor. However, the PCA model also had a small contribution from PC3 (Figure 26G) that should be important for analysis of mixtures.
Figure 26
Figure 26. Discrimination between 10 individual vapors (9 alcohols from their homologous series and water as interferent) using an individual resonant sensor. (A–D) Individual sensor responses Fp, F1, F2, and Zp as representative examples. (E) Plot of raw responses of Zp vs Fp. PCA scores plots of (F) PC1 vs PC2 and (G) PC1 vs PC2 vs PC3 of the developed PCA model upon sensor exposure to various concentrations of vapors: (1) water, (2) methanol, (3) ethanol, (4) 1-propanol, (5) 1-butanol, (6) 1-pentanol, (7) 1-hexanol, (8) 1-heptanol, (9) 1-octanol, and (10) 1-nonanol.
To tune selectivity of a resonant multivariable sensor to a particular linear alcohol, several ligands have been computationally selected for preferential detection of a specific alcohol vapor and to benefit from the multivariable response of resonant impedance sensors. To achieve this goal, the linear solvation energy relationships (LSER) modeling (303, 304) was implemented. The LSER is an effective guide for determination of vapor responses of polymers, (187, 305-307) fullerenes, (308) ligand-capped metal nanoparticles, (309) and DNA. (118) The LSER method calculates material/vapor partition coefficients K as a linear combination of terms that represent several molecular types of interactions: log K = c + rR2 + sπ2H + a∑α2H + b∑β2H + l log L16, where R2, π2H, α2H, β2H, and log L16 are solvation parameters of the vapor in the sensing material, coefficients r, s, a, b, and l are the corresponding sensing material parameters, and c is the constant. (303, 304) The partition coefficients K were calculated by using R2, π2H, α2H, β2H, and log L16 solvation parameters of alcohol vapors (304, 310) and r, s, a, b, and l parameters of different ligands. (309) Further, the volume fractions of vapors of interest in φA the sensing material were calculated using values of liquid analyte molar mass M and density ρ, partial pressure of analyte vapor PA, and gas constant R as φA = K(M/ρ)(PA/(RT)). (311) Next, various combinations of r, s, a, b, and l were generated to evaluate the LSER values for possible new ligand candidates for tuned vapor response. These computed parameters of the sensing material provided the design features for new ligands for the detection of homologous series of alcohols. Figure 27 illustrates examples of predicted ligands for enhanced volume fractions of methanol, 1-butanol, 1-hexanol, and 1-nonanol and suppressed volume fractions for other alcohol vapors and water vapor as an interference. Thus, the tunable sensor selectivity was demonstrated to particular linear alcohols by using computationally selected ligands.
Figure 27
Figure 27. Results of LSER tuning of the volume fractions of vapors of interest φA in ligand-capped metal nanoparticles as sensing materials for multivariable sensors. LSER-predicted functionality of ligand-capped metal nanoparticles preferentially sensitive to model vapors of interest: (A) methanol, (B) 1-butanol, (C) 1-hexanol, and (D) 1-nonanol as highlighted by arrows. The predicted ligand structures shown in A–D may have different stability.
A 3-D dispersion was achieved in another RLC resonant sensor that utilized Au nanoparticles capped with an organic soft linker ligand. (312) The time plots of the first four PCs of the developed PCA model (Figure 28) showed the distinct recognition pattern for PC1, PC2, and PC3 and more noisy results for PC4 between four model vapors (water, methyl salicylate, toluene, and acetone).
Figure 28
Figure 28. High-dispersion response of an individual sensor illustrated as PC1–PC4 time traces. Vapors: (1) H2O, (2) methyl salicylate (MeS), (3) toluene, and (4) acetone at various concentrations. (312)
Significantly suppressed humidity effects have been also demonstrated using octanethiol-capped metal nanoparticles on resonant structures. Using toluene and 1-nonanol as model vapors with high and low vapor pressures, the ability of sensors to operate in the presence of variable ambient humidity and to reject effects of ambient humidity was evaluated in detail. (192, 201) It was found that these sensors rejected up to ∼3 000- and 2 000 000-fold overloading from water vapor when doing measurements of toluene and 1-nonanol, respectively. (192, 201) Such rejection of an excess of an interferent is a significant advancement not only in the development of individual multivariable sensors but also to the development of sensors in general. Previously, numerous types of sensors were shown to suffer from water interference pronounced by a significant baseline offset and analyte signal suppression. (178)
In summary, the majority of reported multivariable impedance nonresonant and resonant sensors demonstrate 2-D response dispersion. (192, 200, 201, 204, 207, 215, 220, 236-238, 241, 243, 244) Examples of reported 3-D (63, 182, 201, 312) and 4-D (180) response dispersion are stimulating for further developments and improvements.
6 Electromechanical Multivariable Resonant Sensors
ARTICLE SECTIONS
Jump To
- Abstract
- 1 Introduction
- 2 Diversity of Applications and Requirements for Modern Gas Sensors
- 3 State of the Art of Existing Sensing Concepts
- 4 General Principles of Multivariable Sensors
- 5 Multivariable Nonresonant and Resonant Impedance Sensors
- 6 Electromechanical Multivariable Resonant Sensors
- 7 Multivariable Field-Effect Transistor Sensors
- 8 Multivariable Photonic Resonant Sensors
- 9 Other Multivariable Sensor Technologies
- 10 Design Criteria for Multivariable Sensors
- 11 Benefits of Multivariable Sensors
- 12 Summary and Development Trends of Single-Output and Multivariable Sensors
- Author Information
- Biography
- Acknowledgment
- References
- Cited By
Electromechanical resonant sensors measure the vapor-modulated changes of mass, viscoelasticity, and electrical loss of a sensing material. The most widely demonstrated designs of these sensors include resonant structures such as thickness shear mode resonators (also known as quartz crystal microbalances, QCMs), acoustic wave devices, tuning forks, and microcantilevers. (313-318) Electromechanical resonant sensors can be described using an RLC circuit with several components such as R (energy loss), L (mass/motional inertia of bare resonator), C (substrate elasticity), and CP (resonator parasitic capacitance) that form acoustic and electrical branches (Figure 29). (319) A sensing material applied to the resonator adds new components such as inductance LS (related to additional mass) and resistance RS (related to acoustic energy dissipation). (319)
Figure 29
Figure 29. Simplified equivalent RLC circuit of an electromechanical multivariable resonant sensor. Circuit components: R (energy loss), L (mass/motional inertia of bare resonator), C (substrate elasticity), and CP (resonator parasitic capacitance) form acoustic and electrical branches of the resonator. Sensing material adds inductance LS (related to additional mass) and resistance RS (related to acoustic energy dissipation). Reprinted with permission from ref 319. Copyright 2004 Elsevier.
Numerous types of sensing materials have been explored with electromechanical resonant transducers (e.g., dielectric and conjugated polymers, (313, 316, 317, 320, 321) ionic liquids, (185) cage compounds, (319, 321) polycyclic aromatic hydrocarbons, (315) ligand-capped metal nanoparticles, (322) nanostructured materials, (318) and composite films (314, 323, 324)). Recent reviews cover advances in electromechanical resonant single-output sensors. (325, 326)
Different types of electromechanical resonant structures have been demonstrated as multivariable sensors when coated with different types of sensing materials. (185, 313, 314, 327, 328) Independent output parameters of individual devices were measured to create multivariable sensors, for example, frequency, absolute quality factor, and amplitude of oscillation, (329) wave propagation velocity and attenuation, (327) resonant frequency and resonant admittance, (330) circuit resistance, and resonant frequency. (319, 328, 331, 332) Also, broadband excitation was applied to tuning forks and microcantilevers followed by the Fourier transform of their output to quantify frequency, quality factor, and amplitude of the mechanical resonance, capacitance, and transmitted electrical phase shift. (313) Further, multiple-frequency resonant devices have been demonstrated over the MHz–GHz range to correct for fluctuations of environmental effects and to improve discrimination of vapors. (333-335)
Recently, an important advancement in discrimination between different types of polar and nonpolar vapors has been demonstrated using an individual QCM resonator coated with a composite film comprising cellulose acetate and a solid-phase organic salt. (314) The salt was 1-n-butyl-2,3-dimethylimidazolium hexafluorophosphate from a Group of Uniform Materials Based on Organic Salts (GUMBOS). Multivariable response of the QCM was achieved by measurements of the changes in resonance frequency Δf and the changes in motional resistance ΔR. (319, 328, 331, 332) Unlike earlier results with only two (319, 332) or three vapors, (331) these recent studies (314) demonstrated the ability to discriminate between a large number of model polar and nonpolar vapors such as methanol, acetonitrile, ethanol, acetone, 1-propanol, toluene, chloroform, and carbon tetrachloride (Figure 30). It was also found that the ratio Δf/ΔR was a concentration-independent quantity proportional to the molecular weight of the absorbed vapors.
Figure 30
Figure 30. Measurements of circuit resistance ΔR and resonant frequency Δf of a QCM sensor for discrimination between different types of polar and nonpolar vapors at various concentrations. Sensing material: composite film comprising cellulose acetate and a solid-phase organic salt. Reprinted with permission from ref 314. Copyright 2012 The Royal Society of Chemistry.
An elegant approach to improve selectivity of vapor sensors was demonstrated by taking advantage of multiharmonic measurements of QCM sensors with dissipation monitoring (QCM-D) based on a ring-down technique. (185) Operation of QCM-D transducers at multiple harmonics (329) has already extensively benefited in the biological studies of biological films. (336) For multivariable sensing of multiple vapors, a QCM-D transducer was coated with a film of an ionic liquid (1-octyl-3-methylimidazolium bromide or 1-octyl-3-methylimidazolium thiocyanate) and its response was measured at multiple harmonics. The sensor was exposed to 18 different organic vapors such as alcohols, hydrocarbons, chlorohydrocarbons, and nitriles. The resulting frequency shifts were measured at seven harmonics and evaluated using PCA and DA. An example of a canonical plot of a DA model is presented in Figure 31. (185) The 2-D and 3-D response dispersions were demonstrated with good vapors classification.
Figure 31
Figure 31. Canonical plot of a DA model based on measurements of resonant frequency Δf at multiple harmonics of a QCM-D sensor for discrimination between different vapors. Sensing material: ionic liquid. Reprinted with permission from ref 185. Copyright 2015 American Chemical Society.
Electrical and electromechanical RLC resonant sensors have been compared for their ability for multivariable operation using gold nanoparticles capped with a peptide AYSSGAPPMPPF as a sensing material. (337) Both resonators were exposed to eight model analyte vapors (acetonitrile, dichloromethane, methyl salicylate, ethanol, toluene, 1-pentanol, chloroform, and salicylaldehyde). From the developed PCA models, it was found that that the electrical RLC resonant sensor was more selective than the electromechanical QCM sensor. The contribution of PC2 in the electrical sensor was four times larger over the QCM sensor: 87.88% and 11.90% for PC1 and PC2 in the electrical sensor and 95.70% and 2.87% for PC1 and PC2 in the QCM sensor, respectively.
In summary, reported multivariable electromechanical resonant sensors typically demonstrate 2-D response dispersion. (314, 319, 331, 337) Sensors based on multiharmonic measurements and ionic liquid sensing materials have been shown to exhibit 3-D response dispersion. (185)
7 Multivariable Field-Effect Transistor Sensors
ARTICLE SECTIONS
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- Abstract
- 1 Introduction
- 2 Diversity of Applications and Requirements for Modern Gas Sensors
- 3 State of the Art of Existing Sensing Concepts
- 4 General Principles of Multivariable Sensors
- 5 Multivariable Nonresonant and Resonant Impedance Sensors
- 6 Electromechanical Multivariable Resonant Sensors
- 7 Multivariable Field-Effect Transistor Sensors
- 8 Multivariable Photonic Resonant Sensors
- 9 Other Multivariable Sensor Technologies
- 10 Design Criteria for Multivariable Sensors
- 11 Benefits of Multivariable Sensors
- 12 Summary and Development Trends of Single-Output and Multivariable Sensors
- Author Information
- Biography
- Acknowledgment
- References
- Cited By
Field-effect transistors (FETs) for gas sensing were introduced in the 1970s (338) when interactions of gases with an active region of the transistor (e.g., its gate) were recognized to produce significant changes of the electronic work function of the sensing material affecting the transistor threshold voltage. Compared to chemiresistors, transistors can have an amplified response, due to the current modulation by the gate electrode, (339) allowing a 100-fold boost in sensitivity. (340)
Initially, the gate materials were inorganic films of catalytic metals (e.g., Pt, Ir, and Pd) and metal oxides (e.g., SnO2 and Ga2O3) at elevated operation temperatures to avoid difficulties with adsorbed water molecules and to speed up the response. (341, 342) These studies resulted in commercialized single-output FET gas sensors. (343) Over the years, the range of sensing materials on FETs has expanded to include Ba1–xSrxTiO3, Ir/WO3, NaNO2, and other materials. (344-346) Semiconducting 1D nanomaterials (e.g., Si, TiO2, ZnO, SnO2, and V2O5) have been also demonstrated (340, 347, 348) as well as 2D materials (e.g., graphene oxide and molybdenum disulfide). (349, 350) Organic, polymeric, and oligomeric thin-film semiconductors are also attracting attention as sensing materials for FETs (e.g., oligo- and polythiophenes, polyaniline, naphthalenes, phthalocyanines, naphthalocyanines, pentacene, polypyrrole, poly(phenylene ethynylene), polycyclic aromatic hydrocarbons, and hexyltrichlorosilanes). (351-354) Excellent “classic” and recent reviews describe the state of the art in field-effect transistors for gas sensing. (256, 339, 341, 352, 355-362)
The role of field-effect transistors in multivariable gas sensing is steadily increasing. The notable initial examples include studies of SnO2 gate (363) and metal catalytic gate (364) transistors at different bias conditions. Measurements of four output parameters from an organic thin-film transistor were demonstrated that included the bulk conductivity of the organic sensing film, the field-induced conductivity, the threshold voltage, and the field-effect mobility. (181)
A platinum gate SiC-FET was studied for quantification of hazardous indoor air pollutants such as benzene, naphthalene, and formaldehyde independent of the level of background humidity using temperature cycling with three plateaus at 180, 200, and 220 °C. (365) Linear discriminant analysis of resulting response patterns has been performed (Figure 32A), (365) demonstrating 2-D dispersion in detection of these selected volatiles in synthetic air. The temperature-cycled operation of the platinum gate SiC-FET was also combined with its gate bias modulation to provide sensor selectivity for discrimination of CO, NO2, and NH3 (Figure 32B). (366) This SiC-FET sensor also demonstrated 2-D dispersion but with relatively small contribution of the second discriminant function. The temperature-cycled operation of the single-crystalline SnO2 nanowires FET was also combined with its gate control to provide sensor selectivity for discrimination of acetone, ethanol, and methyl ethyl ketone. (367)
Figure 32
Figure 32. Platinum gate SiC-FET as a multivariable sensor for discrimination of different volatiles upon analysis of the response patterns using LDA. (A) Results of temperature cycling of the sensor for discrimination of benzene, naphthalene, and formaldehyde at different humidity levels. (365) (B) Results of temperature cycling combined with gate bias modulation of the sensor for discrimination of CO, NO2, and NH3. (366) (A) Reprinted with permission from ref 365. Copyright 2015 Elsevier. (B) Reprinted with permission from ref 366. Copyright 2014 Elsevier.
Analysis of noise spectral density of individual chemiresistors was shown to have a potential to identify various vapors. (368) Such an approach was recently adapted for analysis of low-frequency noise spectra of a graphene gate FET upon its exposure to vapors of different solvents such as methanol, ethanol, tetrahydrofuran, chloroform, acetonitrile, toluene, and methylene chloride. (100) Some volatiles (e.g., methanol, tetrahydrofuran, chloroform, and acetonitrile) exhibited noise spectra with distinctive Lorentzian-shape components due to the vapor-induced charge traps. These results indicated that the low-frequency noise allowed discriminating vapors with a single graphene gate FET. The same approach of discrimination of vapors was also applied to a MoS2 gate FET. (369) However, it was found that, in contrast to graphene, noise spectra changed only upon exposure to acetonitrile vapor.
In another study, a copper phthalocyanine film on a FET with a multivariable readout was used for discrimination of hydrogen peroxide, organic peroxide di-tert-butyl peroxide (TBP), water, and dimethyl methylphosphonate (DMMP) vapors. (370) Multivariable measurements were performed of the source-drain current, mobility, and threshold voltage. Such an approach showed distinct patterns for two peroxides, water, and DMMP vapors (Figure 33A). The positive shifts in the source-drain current and threshold voltage were the diagnostic parameters for peroxides. The results illustrated a dual-response mechanism in which the peroxide molecularly chemisorbed and subsequently catalytically decomposed, forming reactive products and increasing fixed positive charge. A developed PCA model based on the response pattern of these four vapors exhibited 3-D sensor dispersion (Figure 33B).
Figure 33
Figure 33. Copper phthalocyanine gate FET as a multivariable sensor for discrimination of hydrogen peroxide, organic peroxide, water, and dimethyl methylphosphonate (DMMP) vapors. (A) Results of multivariable measurements of the source-drain current, mobility, and threshold voltage demonstrating distinct response patterns for four vapors. (B) PCA scores plot demonstrates 3-D sensor dispersion. Adapted and reproduced with permission from ref 370. Copyright 2012 American Chemical Society.
For selective detection of vapors in single-component and multicomponent mixtures, Si nanowire FETs modified with hexyltrichlorosilanes were used. (193) Several parameters of modified SiNW FETs were measured such as voltage threshold, hole mobility, subthreshold swing, and source-drain current at a minimal gate voltage. An example of diversity of these responses is illustrated in Figure 34A–D. These multiple responses by a single modified SiNW FET created a distinct pattern for each vapor. By analyzing these responses using PCA, a 3-D sensor dispersion was achieved that allowed discrimination of most of the 11 vapors at their single tested concentrations (Figure 34E). Using four outputs of the sensor, an ANN model was also developed based on Euclidean distances to evaluate sensor selectivity. Analysis of binary and ternary mixtures was also performed using a combination of hexane, octane, and hexanol—challenging for the sensor because of the similarity of structures of these vapors. As shown in Figure 34F, ANN was able to identify individual vapors and their binary and ternary mixtures. Such a detection approach has been further explored to detect volatiles that are linked with gastric cancer conditions in exhaled breath and to discriminate them from environmental odors with >85% accuracy. (371)
Figure 34
Figure 34. Si nanowire FET modified with hexyltrichlorosilane for discrimination of 11 diverse vapors. Results of measurements of (A) voltage threshold, (B) subthreshold swing, (C) hole mobility, and (D) source-drain current at a minimal gate voltage demonstrate distinct response patterns for 11 vapors. (193) (E) PCA scores plot demonstrates 3-D sensor dispersion. (F) ANN analysis of binary and ternary mixtures of hexane, octane, and hexanol demonstrates the ability to identify individual vapors and their binary and ternary mixtures. Adapted and reproduced with permission from ref 193. Copyright 2014 American Chemical Society.
In summary, reported multivariable field-effect transistors with inorganic and organic sensing films typically demonstrate 2-D (365, 366) and 3-D (193, 370) response dispersion.
8 Multivariable Photonic Resonant Sensors
ARTICLE SECTIONS
Jump To
- Abstract
- 1 Introduction
- 2 Diversity of Applications and Requirements for Modern Gas Sensors
- 3 State of the Art of Existing Sensing Concepts
- 4 General Principles of Multivariable Sensors
- 5 Multivariable Nonresonant and Resonant Impedance Sensors
- 6 Electromechanical Multivariable Resonant Sensors
- 7 Multivariable Field-Effect Transistor Sensors
- 8 Multivariable Photonic Resonant Sensors
- 9 Other Multivariable Sensor Technologies
- 10 Design Criteria for Multivariable Sensors
- 11 Benefits of Multivariable Sensors
- 12 Summary and Development Trends of Single-Output and Multivariable Sensors
- Author Information
- Biography
- Acknowledgment
- References
- Cited By
Photonic multivariable sensors can be categorized as material- and structure-based. Material-based sensors utilize materials with multifunctional properties that allow several partially or fully independent responses. Such materials comprise units that are much smaller than the wavelength of interrogation light. Structure-based sensors utilize physical structures that are responsible for the multivariable performance of these sensors. Such structures comprise units that are comparable with the wavelength of interrogation light.
Material-Based Multivariable Photonic Sensors
Material-based multivariable photonic sensors go back to ratiometric probes that provided light-intensity- (372) or temperature-independent (373) measurements. Follow-up developments included sensing materials formulated with several reporter moieties. (374) Multiwavelength luminescent and colorimetric reporter moieties were demonstrated to respond to different chemicals provided by several reporter units in a moiety. Such reporters were developed to exhibit absorbance, fluorescence, electroluminescence, and other changes in relation to detected chemicals. (375, 376) Compounds for dual-, triple-, and quadruple-channel sensing of volatile and nonvolatile analytes have been demonstrated. (377-383)
Developments in nanotechnology provided controlled synthesis of plasmonic nanoparticles for resonant vapor sensing. Classic sensor arrays based on plasmonic nanoparticles functionalized with soft (384) and rigid (385) layers have been reported. Plasmonic nanoparticles have been functionalized with “soft” organic layers for multivariable gas sensing at room temperature. (74, 386) Nanocomposites of plasmonic nanoparticles with “rigid” inorganic layers of metal oxides provided the ability for gas sensing at elevated temperatures. (95, 387)
The mechanisms of optical vapor response using plasmonic nanoparticles functionalized with a soft organic layer include (1) variation in the interparticle spacing related to the type and concentration of the vapor, (2) variation in the refractive index of the organic layer related to the partition coefficients of vapors sorbed into this ligand shell, and (3) variation of the reflectivity of the metal nanoparticle network film affected by the variations of the film thickness (74) (Figure 35A). These effects allowed discrimination of individual vapors and their mixtures using gold nanoparticles functionalized with a 1-mercapto-(triethylene glycol) methyl ether ligand, selected for its amphiphilic properties to respond to both polar and nonpolar vapors. Six diverse vapors (water, methyl salicylate, tetrahydrofuran, dimethylformamide, ethyl acetate, and benzene) produced plasmonic responses affecting the peak and the short- and long-wavelength shoulders of the plasmonic band. The PCA scores plot illustrated that this sensing film discriminated most of the tested vapors (Figure 35B) ranked in the order of the refractive index of the respective solvent except for water vapor, likely because water was the only polar protic solvent among tested vapors. Sensor response to these volatiles produced only 2-D dispersion. This sensing film was further utilized to quantify ethyl acetate and benzene in their mixtures using PLS.
Figure 35
Figure 35. 3-D network of organothiol-functionalized plasmonic nanoparticles for multivariable gas sensing. (A) Mechanisms facilitating vapor response selectivity involve vapor-induced modulation of interparticle spacing D, dielectric constant εr and refractive index n of the ligand shell, and film reflectivity R. (B) Discrimination of six individual vapors using a scores plot of a developed PCA model. Each vapor concentration is represented by two replicate exposures. Dashed line is film response to different vapors in the order of the refractive index n of the corresponding solvent. The sensor was exposed to varying concentrations of vapors: (1) water, (2) methyl salicylate, (3) tetrahydrofuran, (4) dimethylformamide, (5) ethyl acetate, and (6) benzene. Reprinted with permission from ref 74. Copyright 2013 Wiley-VCH Verlag GmbH & Co KGaA.
The mechanisms of vapor response using plasmonic nanoparticles in nanocomposite films with metal oxides and operating at high temperatures (300–800 °C) involve the charge exchange with the nanoparticles or a change in the dielectric constant surrounding the nanoparticles, dependent on the type of metal oxide and its morphology. (95) The material of reported nanoparticles was typically gold or gold alloys; examples of metal oxides in such plasmonic films include CuO, ZnO, TiO2, NiO-SiO2, SiO2, BaO, CeO2, and yttria-stabilized zirconia (YSZ, ZrO2, and Y2O3). (95, 385, 387-393)
Most of the reported nanocomposite plasmonic films with metal oxides have not been explored yet for their multivariable responses to different gases. Only several metal oxides have been used in multivariable plasmonic sensing. They did show important results such as 3-D dispersion. Au-CeO2 nanocomposite films were used for multivariable sensing of individual H2, CO, and NO2 gases at 500 °C. (95) Spectral multivariate analysis was used to gauge the inherent selectivity of the film between the separate analytes. The PCA model had three PCs shown in Figure 36 (95) and demonstrated identifiable responses for each gas. Similarly, the use of a Au-TiO2 nanocomposite film at 500 °C also provided three PCs in its PCA model. (385) To eliminate the need for a white light source and to take advantage of a thermal emission of the sensing material at high temperature, lithographically patterned Au nanorods were used upon tuning of their absorption peak into the near-infrared. An Au nanorod–YSZ nanocomposite film was used for multivariable sensing of H2, CO, and NO2 gases at 500 °C. (387) The plasmonic absorption spectrum of the sensing film overlapped with the thermal energy emitted by the tube furnace and the calculated spectral irradiance from Planck’s distribution, providing opportunities for the detection of white light and thermal spectra from the sensing film over the 600–1000 nm wavelength range. The multivariable gas response achieved by using a passive thermal emission of the film was compared to results using a white light source for film illumination. Illumination with the white light source provided a slightly better discrimination between three gases versus thermal imaging where the two reducing gases were not discriminated well.
Figure 36
Figure 36. Au-CeO2 nanocomposite film for multivariable gas sensing at high temperature. Model gases: H2, CO, and NO2 at 500 °C. PCA scores plots showing the data projected onto the PC axes: (A) PC1 vs PC2 and (B) PC2 vs PC3. Nonoverlapping clusters indicate a unique response to each of the three analytes. Data marker size increases with increasing concentration. Reprinted with permission from ref 95. Copyright 2012 American Chemical Society.
Structure-Based Multivariable Photonic Sensors
Structure-based multivariable photonic sensors have been recently reported to demonstrate improvements over conventional single-output sensors and sensor arrays. Previous photonic structure-based vapor sensors operated on single-output vapor quantitation principles based on detection of wavelength shift of the resonance peak measured with a spectrometer (397, 398) or signal-intensity change measured at a single wavelength. (399) These sensors were based on porous silicon, self-assembled colloidal particles, mesoporous photonic crystals, inverse opals, and high-Q resonators as analyzed in recent reviews. (400-411) Traditionally, for monitoring of multiple analytes, such sensors were combined in an array with each sensor having a partial response selectivity to a certain class of analytes. (397, 412)
Recently, multivariable vapor sensing has been accomplished using a composite structurally colored colloidal crystal film self-assembled from polystyrene core nanospheres with a sol–gel shell (Figure 37). (96) The detection mechanism was based on the vapor-induced changes of the optical lattice constant of this composite colloidal crystal array where the polystyrene cores of the nanospheres were preferentially responding to nonpolar vapors while the sol–gel shells were affected mostly by polar vapors. The associated vapor-induced variations in the shape of the Bragg diffraction band were resolved using PCA of differential reflectance spectra. For the evaluation of the response of the sensor, four model vapors of different polarities were selected (water, acetonitrile, dichloromethane, and toluene). The best selectivity was obtained between nonpolar vapors, with less resolution of polar vapors. The built PCA model provided a 3-D response dispersion of the sensor.
Figure 37
Figure 37. Structurally colored colloidal crystal film formed from composite core/shell nanospheres for multivariable gas sensing. (A–D) Differential reflectance spectra for four vapors: water, acetonitrile (ACN), dichloromethane (DCM), and toluene, respectively, at various concentrations. (E) PCA scores plot of response of the colloidal sensor film for four tested vapors demonstrating 3-D dispersion. (F) Reflected light image of the sensing film on a Teflon support. Reprinted with permission from ref 96. Copyright 2008 Institute of Electrical and Electronics Engineers.
Natural biological nanostructures have been the recent focus of growing attention for bioinspired sensing and other technological applications. (97, 413-415) This interest is driven by the design features of these nanostructures that provided geometries that are difficult to reproduce using existing nanofabrication tools but attractive for sensing. In particular, iridescence of tropical Morpho butterflies (Figure 38A) (99) is attractive because it is produced by microscopic scales that have a nanostructure with an open-air architecture (98) that allows vapors to interact with all its regions. Ridges of the scales act as a diffraction grating and lamella of the ridges act as multilayer interferometric nanoreflectors. (416) These biological nanostructures were visualized using electron microscopy of bare (Figure 38B) (98) and Al2O3-coated (Figure 38C) samples.
Figure 38
Figure 38. High vapor-selectivity of natural Morpho scales. (A) Iridescent coloration of Morpho sulkowskyi scales. Images of (B) bare and (C) Al2O3-coated ridge nanostructures with lamellae. (D) Image of conformal epicuticle on the lamellae. An out-of-plane microrib is also visible. (E) Schematic of the tree-like tapered structure of natural butterfly scales with its chemical gradient of surface polarity. (A, E) Reprinted with permission from ref 99. Copyright 2015 Nature Publishing Group. (B, D) Reprinted with permission from ref 98. Copyright 2013 The National Academy of Sciences USA.
Initially, iridescent scales of the Morpho butterflies provided an unexpected diverse optical response to different vapors. (97) This finding inspired further studies in this direction. (414, 417-427) The origin of this vapor selectivity was found to be a gradient of surface polarity of the <10 nm thick epicuticle layer of the ridge structure (Figure 38D). (98) This polarity gradient runs from the polar tops to the less-polar bottoms of ridges. Diverse types of lipids, proteins, and other biomolecules are spatially distributed in the epicuticle layer, forming a polarity gradient and facilitating adsorption and absorption effects of vapors. The mechanism of selective vapor response of the Morpho scales was described to involve preferential sorption of vapors of different polarities onto the corresponding regions of the nanostructured ridge (Figure 38E). (99) Such vapor interactions are expressed in the corresponding regions of the reflected light spectrum, responsible for the unusual vapor response selectivity of the Morpho scales.
Differential spectral reflectance responses ΔR of the Morpho scales to vapors of closely related polarity (water, methanol, and ethanol) showed spectral differences, mostly in the violet–blue regions (Figure 39A–C). (97) The PCA results illustrated the discrimination of all the vapors (Figure 39D) demonstrating strong 3-D dispersion. (97) To explain the experimentally observed results, spectral responses were computed upon a uniform and gradient coverage of the Morpho structure with different adsorbed vapors. (98) With a uniform coverage, computed spectra did not explain the experimental results. Simulations of gradient coverage produced reflectance spectra that formed individual response directions in the PCA scores plot, similar to experimental results. (97)
Figure 39
Figure 39. High vapor selectivity of natural Morpho scales. (A–C) Differential reflectance spectra upon exposure to water, methanol, and ethanol vapors, respectively, at various concentrations. (D) PCA scores plot illustrating discrimination of water, methanol, and ethanol vapors with a 3-D dispersion. Reprinted with permission from ref 97. Copyright 2007 Nature Publishing Group.
Besides using scales of Morpho butterflies, vapor-sensing experiments were also performed using other types of iridescent butterflies. (425, 428) Scales of Polyommatus icarus were utilized for measurements of responses to diverse model vapors (Figure 40A). (425) When a 5 nm thick conformal Al2O3 coating was applied onto the photonic structure of the Polyommatus icarus butterfly, this thin film intended to isolate the epicuticle from the vapors. Indeed, the vapor-response pattern was significantly modified (Figure 40B), demonstrating the possibility for tuning of vapor interactions using the Al2O3 coating. The contributions of PC3 in bare and Al2O3-modified wing scales were 8.67% and 4.84%, respectively.
Figure 40
Figure 40. Tuning of vapor selectivity of Polyommatus icarus butterfly scales. PCA scores plots of spectral responses to diverse vapors at their various concentrations of (A) bare wing scales and (B) wing scales conformally covered by 5 nm Al2O3. Adapted and reproduced with permission from ref 425. Copyright 2014 Elsevier.
Bioinspired interference-stack sensors were fabricated utilizing electron beam lithography (Figure 41A) with physical and chemical features for vapor-selectivity control. (99) The physical design utilized not only optical interference and diffraction in the fabricated periodic nanostructures but also a small optical loss in the nanostructure that provided signatures of reflectance spectra from different regions of the ridge. The chemical design utilized spatially controlled nanostructure functionalization to promote distinct interactions of diverse vapors within the sensor. Similar to iridescence of Morpho scales (Figure 38A), structure-dependent iridescence was observed from fabricated nanostructures (Figure 41B).
Figure 41
Figure 41. Fabricated photonic sensors inspired by Morpho butterflies. (A) Scanning electron microscopy (SEM) image of fabricated six-lamellae nanostructure. (B) Iridescent coloration of fabricated nanostructures. Shown are six regions of nanostructures that were fabricated with and without lamella; each region was 2 × 2 mm. Upon illumination with a white light, three replicate regions of nanostructures with lamella reflected blue light while three other replicate regions of nanostructures without lamella (with only ridges) reflected red light. Reprinted with permission from ref 99. Copyright 2015 Nature Publishing Group.
Selectivity of fabricated nanostructured sensors was tested in numerous scenarios of increasing complexity. Tests with vapors of diverse nature were performed using benzene, methyl ethyl ketone, acetonitrile, methanol, and water, producing differential reflectance spectra ΔR for each vapor (Figure 42A–E). (99) The PCA results illustrated the discrimination of all the vapors with 4-D response dispersion (Figure 42F, G). (99) These sensors were further tested with the challenging combination of methanol and ethanol and with variable water vapor background. Fabricated nanostructured sensors had excellent discrimination of methanol and ethanol vapors even when vapors were mixed with water vapor. Figure 43 illustrates the sensor ability to quantify methanol and ethanol in the presence of variable water vapor background. (99)
Figure 42
Figure 42. High vapor selectivity of a fabricated photonic sensor inspired by Morpho butterflies. (A–E) Differential reflectance spectra upon exposure to benzene (Ben), acetonitrile (ACN), methyl ethyl ketone (MEK), methanol (MeOH), and water (H2O) vapors at their various concentrations. (F) PCA scores plot of PC1 vs PC2 vs PC3 illustrating discrimination of vapors. (G) PCA scores plot of PC2 vs PC4 illustrating discrimination of vapors with a 4-D response dispersion. Reprinted with permission from ref 99. Copyright 2015 Nature Publishing Group.
Figure 43
Figure 43. Fabricated photonic sensor inspired by Morpho butterflies detects individual methanol (MeOH) and ethanol (EtOH) vapors and their mixtures in the presence of different levels of water vapor background. (A–D) ΔR sensor responses at 393, 546, 563, and 950 nm, respectively. Correlation plots between the actual and predicted concentrations of (E) MeOH and (F) EtOH vapors in the presence of different levels of background water vapor. Reprinted with permission from ref 99. Copyright 2015 Nature Publishing Group.
In summary, reported multivariable photonic resonant sensors demonstrate 2-D, (74, 387) 3-D, (95, 96, 98, 385, 421, 425, 427-429) and 4-D (99) response dispersion.
9 Other Multivariable Sensor Technologies
ARTICLE SECTIONS
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- Abstract
- 1 Introduction
- 2 Diversity of Applications and Requirements for Modern Gas Sensors
- 3 State of the Art of Existing Sensing Concepts
- 4 General Principles of Multivariable Sensors
- 5 Multivariable Nonresonant and Resonant Impedance Sensors
- 6 Electromechanical Multivariable Resonant Sensors
- 7 Multivariable Field-Effect Transistor Sensors
- 8 Multivariable Photonic Resonant Sensors
- 9 Other Multivariable Sensor Technologies
- 10 Design Criteria for Multivariable Sensors
- 11 Benefits of Multivariable Sensors
- 12 Summary and Development Trends of Single-Output and Multivariable Sensors
- Author Information
- Biography
- Acknowledgment
- References
- Cited By
Several other types of multivariable sensors have been also developed with outputs of either the same or different types of energy such as optical, electrical, mechanical, or thermal. Two types of optical outputs were combined in a sensor that provided simultaneous measurements of guided optical wave scattering and reflection. (430) Optical and electrical outputs were combined in several types of multivariable sensors. One such sensor was developed to monitor the resonance wavelength of a porous silicon microcavity and its electrical conductivity. (431) Another dual-transduction-mode sensor utilized electrical and optical output signals from a light-emitting organic field-effect transistor with a vapor-sensitive layered structure. (432) It was suggested that using several output variables such as channel conductance, trans-conductance, threshold voltage, light emission intensity, spectrum of the emitted light, location of the emission zone in the channel region, and temporal characteristics of different transduction properties upon exposure to the analyte should enhance sensor dispersion. Thermal and mechanical outputs were combined in another sensor that measured heat dissipation and resonant damping in a microcantilevers. (433) Electrical and mechanical outputs were combined in a sensor that measured conductance and bending of the microhot plate due to volume change of functional layers. (434)
Two types of electrical outputs were combined in a sensor that measured conductance and surface work function of a nanostructured graphite film. (435) These measurements were applied to discriminate several individual model gases as illustrated in Figure 44. (435) It was suggested that this approach can identify gases irrespective of their concentration. Two types of electrical outputs were combined in another sensor that provided simultaneous measurements of resistance and Seebeck coefficient (i.e., thermoelectric sensitivity) of a SnO2 gas sensing material, allowing identification of different reducing gases and determination of their concentrations (436) as illustrated in Figure 45.
Figure 44
Figure 44. Measurements of conductance and surface work function of a nanostructured graphite film for concentration-independent discrimination of individual gases. Sensitivity to respective vapors (as mV/% change of conductance) is shown in parentheses. Reprinted with permission from ref 435. Copyright 2008 American Institute of Physics.
Figure 45
Figure 45. Measurements of resistance and Seebeck coefficient of a SnO2 gas sensing material for identification of different reducing gases and determination of their concentrations. Reprinted with permission from ref 436. Copyright 1998 Elsevier.
10 Design Criteria for Multivariable Sensors
ARTICLE SECTIONS
Jump To
- Abstract
- 1 Introduction
- 2 Diversity of Applications and Requirements for Modern Gas Sensors
- 3 State of the Art of Existing Sensing Concepts
- 4 General Principles of Multivariable Sensors
- 5 Multivariable Nonresonant and Resonant Impedance Sensors
- 6 Electromechanical Multivariable Resonant Sensors
- 7 Multivariable Field-Effect Transistor Sensors
- 8 Multivariable Photonic Resonant Sensors
- 9 Other Multivariable Sensor Technologies
- 10 Design Criteria for Multivariable Sensors
- 11 Benefits of Multivariable Sensors
- 12 Summary and Development Trends of Single-Output and Multivariable Sensors
- Author Information
- Biography
- Acknowledgment
- References
- Cited By
Over the century of development of gas sensors, (338, 437-440) three key learnings have emerged about their selectivity. First, the requirement for sensor selectivity was found to conflict with the requirement for sensor reversibility. (4) As a result, modern commercially successful sensors include extensive data on gas interferences. (40, 119, 120)Second, the breakthrough in gas selectivity was achieved by using sensor arrays, (131-134) but problems with their drift limited their acceptance in practical applications. (144, 146, 161, 177, 441, 442)Third, carefully designed multivariable transducers with independent outputs (63, 99, 179-186) were found to play the key role in boosting selectivity of individual gas sensors. The general design criteria of such multivariable sensors can be refined to include transducer design, transducer excitation, and material-specific details based on the analysis of reported multivariable sensors, as presented in sections 5–9.
Design Criteria for Multivariable Nonresonant Impedance Sensors
Design criteria for multivariable nonresonant impedance sensors involve the changes in complex permittivity of sensing films when exposed to diverse gases that lead to the predictable variation in capacitance and resistance of the impedance sensor circuit. Semiconducting and conducting sensing films can exhibit several response mechanisms to diverse vapors to independently change their capacitance and conductivity. Dielectric polymers do not exhibit significant changes of their conductivity upon interactions with vapors. However, because of the frequency-related interrelation between the conductivity of the sensing film and the resistance of the sensor circuit, both sensor capacitance and resistance of the sensor circuit do change when dielectric polymers are used as sensing films. Applying such sensing materials onto interdigital electrodes in impedance sensors typically results in 2-D sensor dispersion. To increase dispersion, additional engineering of the transducer/sensing material interface can be done and coupled with the carefully chosen spectral range of sensor excitation. Such sensor design can provide more than a single RC constant of the sensor circuit, where each of the RC constants in the sensor circuit contributes from different portions of the sensor (e.g., bulk of the sensing material and contact capacitance and resistance). When these RC constants are designed to produce different predictable responses to numerous gases of interest and interferences, dispersion above 2-D can be achieved.
Design Criteria for Multivariable Resonant Impedance Sensors
Adding a stand-alone inductor element to the impedance sensor typically does not enhance sensor dispersion beyond its nonresonant operation. However, if the inductor is an integral part of the sensing region, sensor dispersion can be enhanced by changing analyte-induced dimensional properties of the inductor. In addition, if a proximity wireless readout is employed between the sensor inductor coil and the pickup coil of the sensor reader, gas-induced modulation of coupling between these inductors (e.g., by flexing of the sensor as a cantilever) can further enhance sensor dispersion. Multifrequency excitation over the broad frequency ranges in the radio frequency and microwave regions can also provide the capability to take advantage of the spectral dispersion of sensing materials upon their exposure to different gases. The use of power modulation of the sensor excitation also can improve sensor dispersion.
Design Criteria for Multivariable Electromechanical Resonant Sensors
Design criteria for multivariable electromechanical resonant sensors involve the changes in mass, elasticity, and conductivity of sensing films produced by diverse gases that lead to the predictable variation in multiple parameters of the electromechanical sensor circuit and its typical 2-D sensor dispersion. Multifrequency excitation of harmonics over the broad frequency range improves sensor dispersion to 3-D.
Design Criteria for Multivariable Field-Effect Transistor Sensors
Design criteria for multivariable field-effect transistors are steadily evolving and maturing. The variation of gate bias leads to variation of several measured parameters that can provide independent or partially independent outputs leading to 2-D and 3-D response dispersion. Examples of measured parameters include the drain current, drain voltage, and threshold voltage (with inorganic sensing materials operated at high temperature) as well as the bulk conductivity, field-induced conductivity, threshold voltage, and field-effect mobility (with organic sensing materials operated at ambient room temperature).
Design Criteria for Multivariable Photonic Sensors Based on Functionalized Plasmonic Nanoparticles
Design criteria for multivariable photonic sensors based on functionalized plasmonic nanoparticles can be related to plasmonic nanoparticles functionalized with soft organic layers and their operation at ambient room temperature as well as to plasmonic nanoparticles functionalized with metal oxides and their operation at high temperature. The use of soft organic layers involves modulation of the interparticle spacing, refractive index of the organic layer, and reflectivity of the metal nanoparticle network film as a function of the type and concentration of vapors. The use of metal oxides involves modulation of the charge exchange with the nanoparticles or a change in the dielectric constant surrounding the nanoparticles as a function of the type and concentration of vapors. Such effects lead to the change in the shape of the plasmonic band and 2-D and 3-D response dispersion.
Design Criteria for Multivariable Photonic Composite Colloidal Crystal Film Sensors
Design criteria for multivariable photonic composite colloidal crystal film sensors involve composite nanospheres with their cores and shells fabricated from materials that sorb vapors and change their optical lattice constant either by a change in their refractive index (hard core or shell) or by swelling (soft core or shell). When these composite nanospheres are self-assembled into structurally colored colloidal crystal film, diverse vapors induce changes of the optical lattice constant of this composite colloidal crystal array that lead to the associated vapor-induced variations in the shape of the Bragg diffraction band and 3-D response dispersion.
Design Criteria for Multivariable Photonic Interference-Stack Sensors
Design criteria for multivariable photonic interference-stack sensors involve physical and chemical design variables. The physical design uses not only optical interference and diffraction due to the fabricated periodic nanostructures but also a small component of optical loss in the nanostructure. This loss gives rise to distinct signatures of reflectance spectra that are induced by the optical attenuation when light propagates between the top and bottom regions of the interference stack. The chemical design uses spatially controlled nanostructure functionalization to promote distinct interactions of diverse vapors within the sensor. Such design experimentally demonstrated 4-D dispersion and 10-D dispersion in simulations. The use of angle modulation of the sensor excitation also can improve sensor dispersion.
11 Benefits of Multivariable Sensors
ARTICLE SECTIONS
Jump To
- Abstract
- 1 Introduction
- 2 Diversity of Applications and Requirements for Modern Gas Sensors
- 3 State of the Art of Existing Sensing Concepts
- 4 General Principles of Multivariable Sensors
- 5 Multivariable Nonresonant and Resonant Impedance Sensors
- 6 Electromechanical Multivariable Resonant Sensors
- 7 Multivariable Field-Effect Transistor Sensors
- 8 Multivariable Photonic Resonant Sensors
- 9 Other Multivariable Sensor Technologies
- 10 Design Criteria for Multivariable Sensors
- 11 Benefits of Multivariable Sensors
- 12 Summary and Development Trends of Single-Output and Multivariable Sensors
- Author Information
- Biography
- Acknowledgment
- References
- Cited By
Achievements in multivariable individual sensors that are analyzed in this Review illustrate that existing to-date multivariable sensors often have 2-D dispersion, similar to the most reported sensor arrays. Such a level of response dispersion may be sufficient in monitoring situations in a relatively simple background or without the need to quantify multiple gases in their mixtures. Some of the multivariable sensors achieve 3-D and 4-D dispersion, comparable with some advanced sensor arrays. (443) Such high dispersion levels should allow quantitation of gases in their binary or ternary mixtures and correction for environmental interferences such as variable chemical background and temperature. However, the biggest achievements in multivariable individual sensors are three-fold.
First, when a recent multivariable sensor was compared with conventional sensor arrays such as QCM and MOS sensors arrays (selected because of their diverse vapor-detection modalities that include both vapor-sorption and vapor-adsorption effects), it was found that the multivariable sensor demonstrated several performance advantages over the sensor arrays. (99) A fabricated multivariable sensor had the ability to reliably quantify vapors in their mixtures and a better linearity of response. Figure 46A depicts a designed map of concentrations of two model vapors and their binary mixtures mixed with water vapor for studies of responses of all sensors. The multivariable sensor resolved individual vapors as well as their binary and ternary mixtures with variable water vapor levels (Figure 46B). The QCM array resolved well only individual vapors but not vapor mixtures (Figure 46C). The MOS sensors array resolved individual vapors and their mixtures with significant nonlinearities (Figure 46D). Thus, the individual multivariable sensor demonstrated the key performance advantages over tested conventional sensor arrays.
Figure 46
Figure 46. Quantitation of individual vapors and their mixtures in the presence of water vapor background using a recently developed multivariable sensor and two conventional sensor arrays. (A) Designed map of concentrations of two individual vapors and their binary mixtures mixed with water vapor; PCA scores plots of responses of (B) multivariable sensor, (C) QCM sensors array, and (D) MOS sensors array. Vapors: 1, methanol (CH3OH); 2, ethanol (CH2CH3OH) at varying concentrations. Reprinted with permission from ref 99. Copyright 2015 Nature Publishing Group.
Second, the most advanced multivariable individual sensors have a response dispersion compatible or even higher than the most advanced sensor arrays. Recently developed bioinspired photonic multivariable sensors (99) compete with disposable one-time-use sensor arrays that involve strong chemical interactions between sensing materials and gases. (444, 445)Figure 47A illustrates a 9-D dispersion achieved with one such array of dosimeter spots where materials in a 36-element array (Figure 47B) strongly ligate tested vapors, leading to device operation as a disposable vapor dosimeter or a chemical fuse. (135) In contrast to such a dosimeter that has limited applicability because of its complexity and strong competition from established simple visual colorimetric test tubes and strips, an individual multivariable sensor has an even better response dispersion based on the new design principles of individual multivariable sensors. Figure 47C illustrates a computed response dispersion of one of such multivariable sensors that had a bioinspired structure with 10 lamella and a preferential adsorption of 10 vapors onto corresponding lamella regions. (446) Inspired by these computed results, a respective multilamella photonic nanostructure has been fabricated as shown in Figure 47D (447) for its further detailed studies. Additional types of photonic nanostructures were also fabricated using diverse techniques and materials as illustrated in Figure 48. (447-455) These structures can allow further tuning of dispersion of sensor response by physical and chemical design principles.
Figure 47
Figure 47. Comparison of response dispersion of a dosimeter array and a multivariable sensor. (A) Measured 9-D dispersion of a disposable one-time-use dosimeter array. (B) White light image of a 36-element vapor dosimeter array. (C) Computed 11-D dispersion of a multivariable sensor based on bioinspired interference-stack design principles. (446) (D) Fabricated multilamella photonic nanostructure for detailed studies of high dispersion of sensor response. (447) (A, B) Reprinted with permission from ref 135. Copyright 2009 Nature Publishing Group.
Figure 48
Figure 48. Examples of different materials and techniques implemented for fabrication of photonic nanostructures inspired by Morpho and other butterflies. (A) Diamond-like carbon structure fabricated using focused ion-beam chemical vapor deposition. (448) (B) Poly(methyl methacrylate) line-array structure with a lift-off resist fabricated using single-step electron-beam lithography. (449) (C) Poly(methyl methacrylate) superlattice structure fabricated using electron-beam lithography with alternate development/dissolution of poly(methyl methacrylate) and lift-off resist. (450) (D) Poly(methyl methacrylate) structure with the alternating lamellae pattern fabricated using electron-beam lithography. (451) (E) Fifteen-lamella poly(methyl methacrylate) structure fabricated using electron-beam lithography. (447) (F) Inorganic structure with thin ridge fabricated using chemical vapor deposition, UV lithography, and chemical etching. (452) (G) Inorganic structure with thin lamella fabricated using selective under-etching of atomic layer deposited material. (453) (H) Porous hierarchical inorganic structure fabricated using chemical vapor deposition, UV lithography, and chemical etching. (452) (I) Inorganic structure with nine large-area lamella fabricated using conventional photolithography and chemical etching. (J) Inorganic structure fabricated on a 10 cm silicon wafer using conventional photolithography and chemical etching. (K) Photoresist structure fabricated utilizing laser interference lithography. (454) (L) UV-curable epoxy scalloped microplates fabricated utilizing double-molding process. (455) (M) Poly(3-hexylthiophene) structure after soft lithography replication from an inorganic master. (452) (N) Inorganic structure with three materials of lamella fabricated using conventional photolithography and chemical etching. (A) Reprinted with permission from ref 448. Copyright 2005 The Japan Society of Applied Physics. (B) Reprinted with permission from ref 449. Copyright 2007 Wiley-VCH Verlag GmbH & Co KGaA. (C) Reprinted with permission from ref 450. Copyright 2015 Nature Publishing Group. (D) Reprinted with permission from ref 451. Copyright 2013 The Optical Society of America. (F, H, M) Reprinted with permission from ref 452. Copyright 2012 American Vacuum Society. (G) Reprinted with permission from ref 453. Copyright 2016 Institute of Physics. (K) Reprinted with permission from ref 454. Copyright 2015 The Optical Society of America. (L) Reprinted with permission from ref 455. Copyright 2014 The National Academy of Sciences U.S.A.
Third, in long-term applications, the drift of response of sensor arrays is a serious unsolved problem (144, 146, 161, 177, 441, 442) because each sensor in an array has a different sensing material with its own drift and aging, uncorrelated with other sensors. This uncorrelated drift of each sensor leads to significant challenges in keeping sensor arrays within their original calibrations. (144, 146, 161, 177, 441, 442) This problem is minimized down to a single multivariable sensor where instabilities in each output in this sensor are correlated due to the use of only one sensing material and one transducer. These instabilities are corrected more effectively as compared to the uncorrelated drift of each sensor in an array. Figure 49A compares calculation results of the prediction error of an analyte concentration for an exemplary multivariable sensor with five outputs and for arrays of 5, 10, and 20 single-output sensors. (102) In the multivariable sensor, its five outputs were calculated with a correlated drift in the range from 0 to 10% (e.g., assuming sensing material aging). The same range of drift was used to calculate the prediction error of an analyte concentration for sensor arrays but taking into the account their uncorrelated drift. When the drift was zero (i.e., fresh sensors), the prediction error for any sensor array or a multivariable sensor was minimal and the same. However, in the presence of uncontrolled long-term drift, sensor arrays lose their prediction accuracy much faster than a single multivariable sensor. This advantage of multivariable sensors can be a deal-breaker between acceptance and rejection of sensor technologies for demanding applications that are highlighted in Figure 1.
Figure 49
Figure 49. Simulation results of long-term performance of individual multivariable sensors vs sensor arrays. (A) Prediction error and (B) probability of false alarms for an exemplary individual multivariable sensor with five outputs and for arrays of 5, 10, and 20 single-output sensors.
Figure 49B depicts the calculated results of the probability of false alarms for the exemplary multivariable sensor with five outputs and for arrays of 5, 10, and 20 single-output sensors. (102) Even for the same number of outputs, a multivariable sensor had lower false alarms. The advantage of the multivariable sensors increases further versus sensor arrays with even larger number of elements. These calculations demonstrate the impact of multivariable sensors for the improved sensor stability with experimental data collection to follow to validate these theoretical predictions. Such multivariable gas sensors with significantly improved performance over existing individual single-output sensors and sensor arrays would be attractive in scenarios illustrated in Figure 1 when high-selectivity advantages of “classic” analytical instruments would be canceled based on the demanding application requirements.
12 Summary and Development Trends of Single-Output and Multivariable Sensors
ARTICLE SECTIONS
Jump To
- Abstract
- 1 Introduction
- 2 Diversity of Applications and Requirements for Modern Gas Sensors
- 3 State of the Art of Existing Sensing Concepts
- 4 General Principles of Multivariable Sensors
- 5 Multivariable Nonresonant and Resonant Impedance Sensors
- 6 Electromechanical Multivariable Resonant Sensors
- 7 Multivariable Field-Effect Transistor Sensors
- 8 Multivariable Photonic Resonant Sensors
- 9 Other Multivariable Sensor Technologies
- 10 Design Criteria for Multivariable Sensors
- 11 Benefits of Multivariable Sensors
- 12 Summary and Development Trends of Single-Output and Multivariable Sensors
- Author Information
- Biography
- Acknowledgment
- References
- Cited By
Looking Back
Single-output gas sensors have been under development for over 100 years, beginning with sensors based on catalytic metals, metal oxides, polymers, and formulated materials. (338, 437-440) The strongest forces for commercialization of gas sensors have been regulatory, safety, pollution control, and industrial productivity needs. (32, 456) The most widely utilized transduction principles in commercial sensors have been resistance, capacitance, potentiometry, amperometry, and work function, as implemented in single-output MOS, catalytic combustion, electrochemical, and FET sensors.
Sensor arrays (131-134) were introduced ∼70 years after the first individual single-output sensors to mitigate their poor selectivity in gas-detection situations that demand low false alarms. Limitations of sensor arrays outside controlled laboratory conditions have been identified. (141, 142, 457) An excellent summary was compiled about 10 years ago containing over 25 types of sensor arrays from over 20 manufacturers of sensor-array-based and mass-spectrometer-based electronic noses. (143)
Multivariable gas sensors were reported ∼15 years after sensor arrays. (180, 195, 196) Most of those multivariable sensors demonstrated 2-D dispersion that allowed discrimination of individual gases. (195, 196) Some multivariable sensors were reported to discriminate up to four components in mixtures, (180) due to the higher level of sensor dispersion.
Looking at the Present
Single-output gas sensors based on existing concepts of sensing materials and transduction principles have been significantly improved as a result of productive efforts of scientists and engineers focused on the key unmet needs important to users for indoor and outdoor applications of sensors. For example, stability of MOS sensors has been increased, (40) their resistance to poisons has been enhanced, (40) and their power consumption and size have been both significantly reduced. (46) These and other advancements in the “classic” metal oxide resistive sensing concept have boosted these relatively nonselective sensors toward their applications as smartphone-integrated detectors of total air quality in countries with high levels of urban air pollution. (52) Other types of classic sensors, such as electrochemical sensors, also have been advanced. Their power, size, and cost have been significantly reduced with the concurrent enhancements of sensor reliability—all these advancements have led to their broader applications. (458) Examples of commonly used practical solutions to improve reliability of sensors include integration of gas filters onto sensing elements (459, 460) and self-calibration of portable gas sensors during their periodic recharging. (461)
Only a few new sensor detection concepts or sensing materials that were initially demonstrated in the laboratories 10–20 years ago have found their acceptance in practical applications. One of such rare examples is a sensor for explosives detection based on a conjugated polymer at an elevated temperature. (462) Other sensors (e.g., based on fullerenes, carbon nanotubes, semiconducting nanowires, graphene, room-temperature conjugated polymers, and formulated colorimetric sensing materials) have yet to find their wide practical acceptance.
Data acquisition from sensors has been demonstrated using ubiquitous electronics components or systems, initially developed for high-volume applications. Examples of such approaches include cell phone cameras, (463) business card readers, (464) and computer screens (465) for illumination and measurements of gas-induced colorimetric changes of sensing materials, mobile devices such as personal digital assistants (103) and smartphones (466) with auxiliary connected or device-integrated (52) gas sensors, and RFID tags with added gas-sensing capabilities. (23, 194, 200, 278, 467-471) The near-field communication (NFC) protocol that is available in many modern smartphones has been implemented in commercially available NFC RFID sensors for quantitation of chemical and physical parameters (e.g., moisture, humidity, temperature, and glucose). (192, 472-475)
While the number of research publications on sensor arrays and electronic noses has a steady upward trend, at present, electronic noses based on sensor arrays are rarely employed in routine applications outside of scientific laboratories. (161) From the summary of commercial electronic noses compiled about 10 years ago, (143) only mass-spectrometer-based electronic noses are still available; most of the companies that manufactured sensor-array-based electronic noses discontinued their offerings.
Multivariable gas sensors have expanded to the demonstration of diverse principles that can be broadly described as nonresonant and resonant. The nonresonant principles include impedance spectroscopic sensors and multioutput field-effect transistors. The resonant sensors include those that utilize electromagnetic responses (i.e., radio frequency, microwave, terahertz, and optical) and electromechanical responses (i.e., tuning forks, thickness shear mode devices, and acoustic-wave devices). While many of these sensors have only 2-D dispersion, similar to past developments, there is a growing number of multivariable sensors with higher dispersion. Recent experimental examples of 3–4-D dispersion include radio frequency and optical resonant sensors as well as field-effect transistors. A summary of recent multivariable sensors with their levels of experimentally achieved dispersion is presented in Table 3. A comparison of different types of multivariable sensors with respect to their dispersion is presented in Figure 50. While the nonresonant and resonant impedance sensors have the most examples in the literature, the vast majority of these sensors have 2-D dispersion followed by examples of 3-D and 4-D dispersion. Sensors that have the most examples of 3-D dispersion are photonic sensors.
Figure 50
Figure 50. Comparison of different types of reported multivariable sensors with respect to their dispersion. The areas of each segment are proportional to the number of publications.
Table 3. Summary of Dispersion of Different Types of Multivariable Sensors
| type of multivariable sensor | literature references on 2-D dispersion | literature references on 3-D dispersion | literature references on 4-D dispersion |
|---|---|---|---|
| electrical multivariable nonresonant and resonant impedance sensors | 192, 200,201, 204, 207, 215, 220, 236−238, 241, 243, 244 | 63, 182, 201, 312 | 180 |
| electromechanical multivariable resonant sensors | 314, 319, 331, 337 | 185 | |
| multivariable field-effect transistor sensors | 365, 366 | 193, 370 | |
| multivariable photonic resonant sensors | 74, 387 | 95, 96, 98, 385, 421, 425, 427−429 | 99 |
| other multivariable sensor technologies | 430−436 |
At present, based on operational requirements, selectivity either may be designed utilizing existing knowledge of materials and transducers or may seek additional future knowledge. In one example, selective monitoring of indoor humidity in the presence of expected nonpolar volatiles in industrial facilities can be successfully designed by using hydrophilic polymers or aluminum oxides coupled with capacitance transducers. (-476-479) However, in another example, selective detection of particular alcohols for determination of molds or fruits condition (480-483) or particular hydrocarbons to determine biogenic or thermogenic origin of their emissions (484) is still a significant scientific challenge for a true design of selective sensors.
Selectivity against the most abundant interferent such as water vapor remains a challenge for most single-output sensors. Humidity effects and their mitigation approaches were detailed in section 5 and touched upon in section 8 because of the most advanced development stages of multivariable impedance and photonic sensors.
As individual sensors, single-output sensors remain the only commercial offering. No multivariable sensors have been broadly commercialized yet.
Looking into the Future
Single-output and multivariable gas sensors will continue to be an attractive opportunity for numerous application scenarios in Internet of Things, Industrial Internet, and other areas when certain specific requirements (e.g., unobtrusive form factor, no external power for operation, no vacuum or carrier gases, and no radioactive sources) cancel the advantages of “classic” analytical instruments. Gas sensors based on sensing materials coupled with an appropriate transducer will continue to compete with microfabricated designs of “classic” analytical instruments such as GC, MS, IMS, and direct spectroscopic gas detectors. This competition will be more enhanced due to the steady advancements in those technologies in their miniaturization, sample handling, and power reduction. (485-487) At the same time, important learnings obtained in those areas (e.g., temperature stabilization, signal conditioning, reduction of fouling, and others) should be more proactively adapted in gas sensors. Sensor arrays will be at the point where they either will demonstrate their cost–benefit capabilities in practical applications or will remain as a laboratory curiosity with yet to be solved practical analytical problems. One of the possible solutions for sensor arrays will be to follow the developments of multivariable sensors—to minimize the number of sensors in an array for its best stability.
Dosimeter-type sensors and their arrays with strong chemical interactions (135) may find more acceptance depending on the cost–benefit proposition in anticipated applications. Classic dosimeters (488, 489) will benefit from the ability to detect numerous gases with one dosimeter cartridge (147) and the ability to store temporally varying chemical information. (490) Dosimeter-type sensors will benefit from new approaches for their resetting by applying different types of energy (e.g., thermal, ultraviolet, and visible). (491-493)
Multivariable gas sensors should continue to advance with their four main thrusts—sensing materials, transducer designs, data analytics, and manufacturability. A system solution for these four main thrusts will provide practical, user-accepted sensor designs for indoor and outdoor applications.
New sensing materials should be explored in three main areas. First, new materials are needed with diverse multiresponse mechanisms for detection of analytes in complex environments. Established materials research tools such as computational, combinatorial, and high-throughput materials design (309, 494-501) should be more proactively utilized for identifying new materials. Future ability to design sensing materials should include quantitative understanding of the mechanisms on atomic and macroscopic scales that describe not only desired interactions between the sensing material and the gas (e.g., sensitivity and selectivity) but also undesired effects (e.g., aging and poisoning). Second, stability and reliability of new sensing materials should be taken into account as early as possible (502-505) in order to properly gauge the next steps in sensor testing because sensor reliability is one of the main requirements for ubiquitous sensors. Third, new concepts should be developed to improve rejection of gaseous interferences—as standalone filters based on new materials or as multiple sensing layers on a transducer. (506)
New transducer designs should be developed to expand sensor dispersion dimensionality beyond 2D dispersion of numerous reported multivariable sensors. These new developments will be in the areas of resonant and nonresonant devices. Exploring different excitation conditions of new transducer designs should assist in identifying new opportunities to enhance sensor dispersion. Excitation will play an increasingly important role for modulation of selectivity of sensing materials by utilizing electrical, optical, temperature, and other stimuli. For example, electrical stimuli can include excitation frequency or excitation voltage; optical stimuli can include light power density, excitation wavelength, or excitation angle; and temperature stimuli can include temperature modulation. Excitation conditions will be also designed to switch between detection mechanisms. For example, operation temperature of semiconducting metal oxide sensors can be utilized to switch material response mechanisms between physisorption at low temperatures, chemisorption at medium temperatures, and bulk effects at high temperatures. Optical excitation of reagent-doped polymeric materials can be utilized to switch between extinction and swelling response mechanisms.
New data analytics will continue to be the key enabler in achieving high-value performance. Different chemometrics tools have been widely accepted in the sensor-development community to demonstrate initial capabilities of sensor systems. However, most of these tools have only little acceptance among users of sensors, not because of the lack of their knowledge of chemometrics but rather due to challenges of reliability of the built chemometric models in routine practical implementations. Results in Figures 21, 26E, 30, 44, and 45 illustrate 2-D sensor dispersion by using original physical signals from multivariable sensors without performing PCA or other types of multivariate analysis. Such ability has been achieved by using the knowledge of diverse response mechanisms of the utilized sensing materials and matching these responses with the appropriate transducer type and its excitation conditions. The underlying principles in the gas-material interactions exploited in these cases involved the previously known diversity of chosen responses to different vapors and the new ability to visualize these responses using matched transduction. Future developments in data analytics should focus on better understanding of trade-offs between using physical signals with and without the multivariate analysis layer to achieve high sensor dispersion and better understanding of noise and drift sources from each of the outputs of a multivariable sensor. Different techniques of conditioning of individual outputs from a multivariable sensor also should be explored with the goal of providing more reliable sensor performance. The best practices in data analytics of dynamic and steady-state features should be shared more proactively across different types of multivariable and other sensors.
Sensor manufacturability, including not only a sensing element but also a sensor reader, will continue to be a critical aspect in acceptance of sensors in practical applications. Approaches for cost-effective manufacturing of sensing elements such as wafer-level fabrication, printing, roll-to-roll, self-assembly, and other techniques (28, 50, 59-66) should be evaluated based on their tolerances, manufacturing volumes, and other critical parameters. Cost analysis of multivariable sensors based on different sensing principles illustrates that sensing elements and sensor readers for different types of sensors can be of similar cost at large manufacturing volumes. (252) Two examples of evolution of sensor readers from the excellent broad-use desktop systems to the low-power microsystems are presented in Figures 51 and 52. (507-509) Electrical sensor readers have diversified from desktop and field-deployable (Figure 51B–D) to discrete-components wearable (Figure 51E, F), and to integrated circuit (Figure 51G, H) readers. The integrated circuit readers can be integrated into mobile and other networked devices (226, 227, 312) or can be connected to these devices. (510) Optical sensor readers have diversified from desktop (Figure 52A) to hand-held (Figure 52B), to microfabricated (Figure 52C), and to integrated attachments for mobile networked devices (Figure 52D). Smartphone camera modules (511-513) and application-specific photonic integrated circuits (32, 252) also can provide desired unobtrusive and cost-effective solutions.
Figure 51
Figure 51. Examples of electrical readout devices for interrogation of multivariable sensors. (A) General view of different devices, (B) desktop network analyzer, (C) fieldable network analyzer, (D) portable impedance analyzer, (E) handheld/wearable impedance analyzer, (F) bluetooth mini network analyzer, (G) integrated circuit impedance analyzer on an evaluation board, and (H) low-power integrated circuit with resistance and capacitance inputs. as a part of an RFID sensor. The scale bars in (B−H) are 2 cm. Logos pictured courtesy of Keysight Technologies, Inc. and WiMo Antennen and Elektronik GmbH.
Figure 52
Figure 52. Examples of optical readout devices for interrogation of multivariable sensors. (A) Portable spectrometer, (B) handheld spectrometer with integrated illumination using multiple light-emitting diodes, (507) (C) ultracompact spectrometer, (508) and (D) smartphone attached spectrometer. (509) Logo pictured courtesy of Ocean Optics, Inc.
These advances in sensing materials, transducer designs, data analytics, and manufacturability will allow new multivariable sensors to outperform not only existing single-output sensors but also sensor arrays in their stability and immunity to humidity and other interferences in numerous practical indoor and outdoor deployments. Multivariable sensors can be considered as a disruptive sensor technology (Figure 53) where high dispersion of an individual sensor response contributes to its high reliability and ability to operate without false alarms.
Figure 53
Figure 53. Disruptive multivariable sensor technologies to complement and ultimately to replace conventional single-output sensors and sensor arrays.
A 2025 roadmap for the development of gas sensors is summarized in Figure 54 with highlighted needed advances in sensor reliability, reduction of sensor cost, and needed operation power. The significant driving forces in these developments will continue to be numerous application scenarios in Internet of Things and Industrial Internet with needed trillions of sensors. (25, 30-32)
Figure 54
Figure 54. 2025 roadmap for development of gas sensors.
Competition between different microanalytical systems for particular types of applications will be enhanced due to significant advances in microfabricated designs of “classic” analytical instruments such as GC, MS, IMS, and direct spectroscopic gas detectors. The key metric for the acceptance of certain technologies in diverse indoor and outdoor applications will remain to be the cost–benefit ratio to the users. The value of multivariable sensors will continue to increase with their ability to discriminate and quantify multiple gases in the presence of known and unknown interferences and closely related gases of different classes and to correct for multiple environmental effects without the added system hardware complexity.
Biography
ARTICLE SECTIONS
Jump To
- Abstract
- 1 Introduction
- 2 Diversity of Applications and Requirements for Modern Gas Sensors
- 3 State of the Art of Existing Sensing Concepts
- 4 General Principles of Multivariable Sensors
- 5 Multivariable Nonresonant and Resonant Impedance Sensors
- 6 Electromechanical Multivariable Resonant Sensors
- 7 Multivariable Field-Effect Transistor Sensors
- 8 Multivariable Photonic Resonant Sensors
- 9 Other Multivariable Sensor Technologies
- 10 Design Criteria for Multivariable Sensors
- 11 Benefits of Multivariable Sensors
- 12 Summary and Development Trends of Single-Output and Multivariable Sensors
- Author Information
- Biography
- Acknowledgment
- References
- Cited By
Radislav A. Potyrailo
Dr. Radislav Potyrailo is a Principal Scientist at GE Global Research in Niskayuna, New York, leading the growth of industrial, wireless, wearable, and harsh environment sensing technologies for GE applications. He holds an Optoelectronics degree from Kiev Polytechnic Institute and Ph.D. in Analytical Chemistry from Indiana University. Radislav has been serving as the GE Principal Investigator on U.S. Government programs funded by AFRL, DARPA, DHS, NETL, NIH, NIOSH, and TSWG. Radislav delivered 80+ invited lectures and nine keynote/plenary lectures at National and International Meetings, has 100+ granted U.S. Patents and 150+ publications, and coauthored/coedited eight books. He serves as an editor of the Springer book series Integrated Analytical Systems. His recent awards include the 2010 Prism Award by SPIE and the 2012 Blodgett Award by GE Research. In 2011 Radislav was elected SPIE Fellow for achievements in fundamental breakthroughs in optical sensing and analytical systems. In 2013 Radislav was elevated to the grade of Senior Member of the IEEE.
Acknowledgment
ARTICLE SECTIONS
Jump To
- Abstract
- 1 Introduction
- 2 Diversity of Applications and Requirements for Modern Gas Sensors
- 3 State of the Art of Existing Sensing Concepts
- 4 General Principles of Multivariable Sensors
- 5 Multivariable Nonresonant and Resonant Impedance Sensors
- 6 Electromechanical Multivariable Resonant Sensors
- 7 Multivariable Field-Effect Transistor Sensors
- 8 Multivariable Photonic Resonant Sensors
- 9 Other Multivariable Sensor Technologies
- 10 Design Criteria for Multivariable Sensors
- 11 Benefits of Multivariable Sensors
- 12 Summary and Development Trends of Single-Output and Multivariable Sensors
- Author Information
- Biography
- Acknowledgment
- References
- Cited By
The author is thankful for the fruitful discussions with many Program Managers at U.S. and non-U.S. Government Agencies and GE businesses who were querying about capabilities and limitations of existing and future sensors and sensor arrays to deliver field-deployable monitoring solutions for demanding existing and emerging applications with a desirable cost/performance ratio. This Review has been inspired by those discussions. Results by General Electric collaborative teams that were cited in this Review were accomplished by creative scientists and engineers who coauthored original referenced contributions: J. Ashe, B. Bartling, V. Bromberg, A. Burns, M. Butts, J. Carter, J. Cella, K. Chichak, V. Cotero, J. Cournoyer, T. Deng, R. Diana, J. Dieringer, Z. Ding, K. Dovidenko, G. Gach, S. Genovese, S. Go, G. Goddard, J. Grande, H. Ehring, S. Hasan, B. Kandapallil, S. Klensmeden, H. Lam, M. Larsen, L. Le Tarte, A. Leach, Y. Lee, K. Lindh, D. Monk, W. Morris, H. Mouquin, N. Nagraj, E. Olson, M. Palacios, V. Pizzi, N. Rao, O. Riccobono, D. Sexton, T. Sivavec, K. Sundaresan, C. Surman, Z. Tang, I. Tokarev, H. Tomlinson, A. Vertiatchikh, M. Vincent, T. Wortley, S. Zalubovsky, S. Zhong, and G. Zorn (General Electric); H. Ghiradella, R. Bonam, and J. Hartley (State University of New York, Albany); T. Starkey and P. Vukusic (University of Exeter); R. Naik, T. Bunning, D. Gallagher, J. Hagen, N. Kelley-Loughnane, W. Lyon, D. Phillips, J. Slocik, and M. Vasudev (Air Force Research Laboratory); D. J. Lee and E. McGinniss (Avery Dennison); H. Boudries and H. Lai (Morpho Detection); G. Hieftje, T. Danielson, M. Johnson, and A. Szumlas (Indiana University); V. Mirsky (Brandenburg University of Technology); S. Rumyantsev and M. Shur (Rensselaer Polytechnic Institute); A. Balandin and G. Liu (University of California—Riverside). Special thanks go to W. Morris and M. Schulmerich for critical contributions on automation of sensor data acquisitions; M. Larsen and Z. Tang for fabricating and analysis of structures in Figure 11; H. Lam for computing data in Figure 27; L. Le Tarte, T. Deng, and S. Zhong for fabricating and analysis of structure in Figure 38C; G. Piszter, K. Kertész, Z. Vértesy, Z. Bálint, and L. Biró for providing Figure 40; T. Starkey for computing spectra processed in Figure 47C; R. Bonam for fabricating structures in Figures 47D and 48E; T. Deng, S. Zhong, and W. Shang for fabricating structures in Figures 48I and 48N; A. Minnik for fabricating structure in Figure 48J; M. Nayeri for computing data in Figure 49; and J. Ashe, W. Morris, J. Iannotti, S. Bulumulla, K. Dufel, and D. Sexton for design of handheld/wearable analyzer in Figure 51E.
References
ARTICLE SECTIONS
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- Abstract
- 1 Introduction
- 2 Diversity of Applications and Requirements for Modern Gas Sensors
- 3 State of the Art of Existing Sensing Concepts
- 4 General Principles of Multivariable Sensors
- 5 Multivariable Nonresonant and Resonant Impedance Sensors
- 6 Electromechanical Multivariable Resonant Sensors
- 7 Multivariable Field-Effect Transistor Sensors
- 8 Multivariable Photonic Resonant Sensors
- 9 Other Multivariable Sensor Technologies
- 10 Design Criteria for Multivariable Sensors
- 11 Benefits of Multivariable Sensors
- 12 Summary and Development Trends of Single-Output and Multivariable Sensors
- Author Information
- Biography
- Acknowledgment
- References
- Cited By
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- 48Strelcov, E.; Dmitriev, S.; Button, B.; Cothren, J.; Sysoev, V.; Kolmakov, A. Evidence of the Self-Heating Effect on Surface Reactivity and Gas Sensing of Metal Oxide Nanowire Chemiresistors Nanotechnology 2008, 19, 355502 DOI: 10.1088/0957-4484/19/35/355502Google Scholar48https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD1cXht1aitr3F&md5=ec921fc4e430390dda34f890e54e9223Evidence of the self-heating effect on surface reactivity and gas sensing of metal oxide nanowire chemiresistorsStrelcov, Evgheni; Dmitriev, Serghei; Button, Bradley; Cothren, Joshua; Sysoev, Victor; Kolmakov, AndreiNanotechnology (2008), 19 (35), 355502/1-355502/5CODEN: NNOTER; ISSN:0957-4484. (Institute of Physics Publishing)The effect of Joule self-heating of the semiconducting metal oxide nanowire (here (and below unless specified), due to the generality of the effect, the authors use the term 'nanowire' without specification as to whether the nanobelt or other class of quasi-1D nanostructure is considered) conductometric gas sensor on its surface reactivity and kinetics is demonstrated. Due to small thermal capacitance and hampered thermal losses from the nanowire to its surroundings, the sensor was able to operate without a heater, consuming only a few microwatts of power. These results demonstrate the importance of the self-heating effect in nanowire electronics and its potential use in chem. and bio-sensing, where the ultra-small size of the active element and minimal power consumption are crucial.
- 49Prades, J. D.; Jimenez-Diaz, R.; Hernandez-Ramirez, F.; Barth, S.; Cirera, A.; Romano-Rodriguez, A.; Mathur, S.; Morante, J. R. Ultralow Power Consumption Gas Sensors Based on Self-Heated Individual Nanowires Appl. Phys. Lett. 2008, 93, 123110 DOI: 10.1063/1.2988265Google Scholar49https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD1cXhtFOrs7vO&md5=464bf393b4f8a3afb98f9356c7a1634eUltralow power consumption gas sensors based on self-heated individual nanowiresPrades, J. D.; Jimenez-Diaz, R.; Hernandez-Ramirez, F.; Barth, S.; Cirera, A.; Romano-Rodriguez, A.; Mathur, S.; Morante, J. R.Applied Physics Letters (2008), 93 (12), 123110/1-123110/3CODEN: APPLAB; ISSN:0003-6951. (American Institute of Physics)Dissipated power in metal oxide nanowires (rNW < 45 nm) often causes important self-heating effects and as a result, undesired aging and failure of the devices. Nevertheless, this effect can be used to optimize the sensing conditions for the detection of various gaseous species, avoiding the requirement of external heaters. The sensing capabilities of self-heated individual SnO2 nanowires toward NO2 are presented. These proof-of-concept systems exhibited responses nearly identical to those obtained with integrated microheaters, demonstrating the feasibility of taking advantage of self-heating in nanowires to develop ultralow power consumption integrated devices. (c) 2008 American Institute of Physics.
- 50Ahn, J. H.; Yun, J.; Moon, D. I.; Choi, Y. K.; Park, I. Self-Heated Silicon Nanowires for High Performance Hydrogen Gas Detection Nanotechnology 2015, 26, 095501 DOI: 10.1088/0957-4484/26/9/095501Google Scholar50https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2MXksFehtLo%253D&md5=3252c3a3c99401d1c1326a7fbff61551Self-heated silicon nanowires for high performance hydrogen gas detectionAhn, Jae-Hyuk; Yun, Jeonghoon; Moon, Dong-Il; Choi, Yang-Kyu; Park, InkyuNanotechnology (2015), 26 (9), 095501CODEN: NNOTER; ISSN:1361-6528. (IOP Publishing Ltd.)Self-heated silicon nanowire sensors for high-performance, ultralow-power hydrogen detection have been developed. A top-down nanofabrication method based on well-established semiconductor manufg. technol. was utilized to fabricate silicon nanowires in wafer scale with high reproducibility and excellent compatibility with electronic readout circuits. Decoration of palladium nanoparticles onto the silicon nanowires enables sensitive and selective detection of hydrogen gas at room temp. Self-heating of silicon nanowire sensors allows us to enhance response and recovery performances to hydrogen gas, and to reduce the influence of interfering gases such as water vapor and carbon monoxide. A short-pulsed heating during recovery was found to be effective for addnl. redn. of operation power as well as recovery characteristics. This self-heated silicon nanowire gas sensor will be suitable for ultralow-power applications such as mobile telecommunication devices and wireless sensing nodes.
- 51Monereo, O.; Prades, J. D.; Cirera, A. Self-Heating Effects in Large Arrangements of Randomly Oriented Carbon Nanofibers: Application to Gas Sensors Sens. Actuators, B 2015, 211, 489– 497 DOI: 10.1016/j.snb.2015.01.095Google Scholar51https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2MXisVSmsbo%253D&md5=d52fbd349e948574f9b196de9a9262e4Self-heating effects in large arrangements of randomly oriented carbon nanofibers: Application to gas sensorsMonereo, O.; Prades, J. D.; Cirera, A.Sensors and Actuators, B: Chemical (2015), 211 (), 489-497CODEN: SABCEB; ISSN:0925-4005. (Elsevier B.V.)Herein, we prove that self-heating effects occur in sensor films made of randomly oriented nanoparticles (electro-sprayed, drop-casted and paint-brushed films of carbon nanofibers). A 2-point calibration method, reliable enough to overcome the lack of reproducibility of low cost fabrication methods, is also proposed. Self-heating operation makes possible reaching temps. up to 250°C with power consumptions in the range of tens of mW. For certain low-temp. applications (<100°C) typical power consumptions are as low as tens of μW. The method is suitable to modulate the response towards gases, such as humidity, NH3 or NO2. This approach overcomes the complex fabrication requirements of previous self-heating investigations and opens the door to use this effect in cost-effective devices.
- 52Johnson, R. C. Gas Sensors Penetrate Smartphones. EE Times 2015; http://www.eetimes.com/document.asp?doc_id=1328199 (accessed July 27, 2016).Google ScholarThere is no corresponding record for this reference.
- 53Biaggi-Labiosa, A.; Solá, F.; Lebrón-Colón, M.; Evans, L. J.; Xu, J. C.; Hunter, G.; Berger, G. M.; González, J. M. A Novel Methane Sensor Based on Porous SnO2 Nanorods: Room Temperature to High Temperature Detection Nanotechnology 2012, 23, 455501 DOI: 10.1088/0957-4484/23/45/455501Google Scholar53https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC3sXhtV2jtrrK&md5=4149e0ca6352349323cd3fe6203201c5A novel methane sensor based on porous SnO2 nanorods: room temperature to high temperature detectionBiaggi-Labiosa, A.; Sola, F.; Lebron-Colon, M.; Evans, L. J.; Xu, J. C.; Hunter, G. W.; Berger, G. M.; Gonzalez, J. M.Nanotechnology (2012), 23 (45), 455501, 8 pp.CODEN: NNOTER; ISSN:1361-6528. (IOP Publishing Ltd.)Reported is a room temp. CH4 sensor fabricated from porous tin oxide (SnO2) nanorods as the sensing material. The porous SnO2 nanorods were prepd. by multiwall carbon nanotubes (MWCNTs) as templates. Current vs. time curves were obtained demonstrating the room temp. sensing capabilities of the sensor system when exposed to 0.25% CH4 in air. The sensor also exhibited a wide temp. range for different concns. of CH4 (25-500°), making it useful in harsh environments as well.
- 54Wang, Z.; Li, Z.; Jiang, T.; Xu, X.; Wang, C. Ultrasensitive Hydrogen Sensor Based on Pd0-Loaded SnO2 Electrospun Nanofibers at Room Temperature ACS Appl. Mater. Interfaces 2013, 5, 2013– 2021 DOI: 10.1021/am3028553Google Scholar54https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC3sXjt1Wmtbg%253D&md5=d64f0aa62791c4ff258f8ddd9e606680Ultrasensitive Hydrogen Sensor Based on Pd0-Loaded SnO2 Electrospun Nanofibers at Room TemperatureWang, Zhaojie; Li, Zhenyu; Jiang, Tingting; Xu, Xiuru; Wang, CeACS Applied Materials & Interfaces (2013), 5 (6), 2013-2021CODEN: AAMICK; ISSN:1944-8244. (American Chemical Society)Pd0-loaded SnO2 nanofibers were successfully synthesized with different loaded levels via electrospinning process, sintering technol., and in situ redn. This simple strategy could be expected to extend for the fabrication of similar metal-oxide loaded nanofibers using different precursors. The morphol. and structural characteristics of the resultant product were studied by SEM, TEM, XRD, and X-ray photoelectron spectra (XPS). To demonstrate the usage of such Pd0-loaded SnO2 nanomaterial, a chem. gas sensor was fabricated and studied for H2 detection. The sensing performances vs. Pd0-loaded levels were studied. An ultralow limit of detection (20 ppb), high response, fast response and recovery, and selectivity were obtained from the sensors operating at room temp. The combination of SnO2 crystal structure and catalytic activity of Pd0-loaded gives a very attractive sensing behavior for applications as real-time monitoring gas sensors.
- 55Liu, H.; Xu, S.; Li, M.; Shao, G.; Song, H.; Zhang, W.; Wei, W.; He, M.; Gao, L.; Song, H.; Tang, J. Chemiresistive Gas Sensors Employing Solution-Processed Metal Oxide Quantum Dot Films Appl. Phys. Lett. 2014, 105, 163104 DOI: 10.1063/1.4900405Google Scholar55https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2cXhvVSqs7fF&md5=9276ebadfa28130c7471b9f0065655deChemiresistive gas sensors employing solution-processed metal oxide quantum dot filmsLiu, Huan; Xu, Songman; Li, Min; Shao, Gang; Song, Huaibing; Zhang, Wenkai; Wei, Wendian; He, Mingze; Gao, Liang; Song, Haisheng; Tang, JiangApplied Physics Letters (2014), 105 (16), 163104/1-163104/5CODEN: APPLAB; ISSN:0003-6951. (American Institute of Physics)The authors report low-temp. chemiresistive gas sensors based on tin oxide colloidal quantum dots (CQDs), in which the benefits of CQDs such as extremely small crystal size, soln.-processability, and tunable surface activity are exploited to enhance the gas-sensing effect. The sensor fabrication is simply employing spin-coating followed by a solid-state ligand exchange treatment at room temp. in air ambient. The optimal gas sensor exhibited rapid and significant decrease in resistance upon H2S gas exposure when operated at 70°, and it was fully recoverable upon gas release. The authors obsd. a power law correlation between the sensor response and H2S gas concn., and the sensing mechanism was discussed using the completely depletion model with a flat band diagram. (c) 2014 American Institute of Physics.
- 56Cheng, W.; Ju, Y.; Payamyar, P.; Primc, D.; Rao, J.; Willa, C.; Koziej, D.; Niederberger, M. Large Area Alignment of Tungsten Oxide Nanowires over Flat and Patterned Substrates for Room-Temperature Gas Sensing Angew. Chem., Int. Ed. 2015, 54, 340– 344 DOI: 10.1002/anie.201408617Google ScholarThere is no corresponding record for this reference.
- 57Gole, J. L. Increasing Energy Efficiency and Sensitivity with Simple Sensor Platforms Talanta 2015, 132, 87– 95 DOI: 10.1016/j.talanta.2014.08.038Google ScholarThere is no corresponding record for this reference.
- 58Helwig, A.; Müller, G.; Sberveglieri, G.; Eickhoff, M. On the Low-Temperature Response of Semiconductor Gas Sensors J. Sens. 2009, 2009, 620720 DOI: 10.1155/2009/620720Google ScholarThere is no corresponding record for this reference.
- 59Xu, L.; Dai, Z.; Duan, G.; Guo, L.; Wang, Y.; Zhou, H.; Liu, Y.; Cai, W.; Wang, Y.; Li, T. Micro/Nano Gas Sensors: A New Strategy Towards in-Situ Wafer-Level Fabrication of High-Performance Gas Sensing Chips Sci. Rep. 2015, 5, 10507 DOI: 10.1038/srep10507Google Scholar59https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A280%3ADC%252BC2Mfnt1ygtA%253D%253D&md5=89caf119d6ebd8dd7faa700251064085Micro/Nano gas sensors: a new strategy towards in-situ wafer-level fabrication of high-performance gas sensing chipsXu Lei; Dai Zhengfei; Duan Guotao; Cai Weiping; Guo Lianfeng; Wang Yi; Zhou Hong; Liu Yanxiang; Wang Yuelin; Li TieScientific reports (2015), 5 (), 10507 ISSN:.Nano-structured gas sensing materials, in particular nanoparticles, nanotubes, and nanowires, enable high sensitivity at a ppb level for gas sensors. For practical applications, it is highly desirable to be able to manufacture such gas sensors in batch and at low cost. We present here a strategy of in-situ wafer-level fabrication of the high-performance micro/nano gas sensing chips by naturally integrating microhotplatform (MHP) with nanopore array (NPA). By introducing colloidal crystal template, a wafer-level ordered homogenous SnO2 NPA is synthesized in-situ on a 4-inch MHP wafer, able to produce thousands of gas sensing units in one batch. The integration of micromachining process and nanofabrication process endues micro/nano gas sensing chips at low cost, high throughput, and with high sensitivity (down to ~20 ppb), fast response time (down to ~1 s), and low power consumption (down to ~30 mW). The proposed strategy of integrating MHP with NPA represents a versatile approach for in-situ wafer-level fabrication of high-performance micro/nano gas sensors for real industrial applications.
- 60Guidi, V.; Malagù, C.; Carotta, M. C.; Vendemiati, B. Printed Semiconducting Gas Sensors Printed Films: Materials Science and Applications in Sensors, Electronics and Photonics 2012, 278– 334 DOI: 10.1533/9780857096210.2.278Google ScholarThere is no corresponding record for this reference.
- 61Bai, L.; Xie, Z.; Wang, W.; Yuan, C.; Zhao, Y.; Mu, Z.; Zhong, Q.; Gu, Z. Bio-Inspired Vapor-Responsive Colloidal Photonic Crystal Patterns by Inkjet Printing ACS Nano 2014, 8, 11094– 11100 DOI: 10.1021/nn504659pGoogle Scholar61https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2cXhslagur3J&md5=7309f67fdb6280f34459e49a3522888cBio-Inspired Vapor-Responsive Colloidal Photonic Crystal Patterns by Inkjet PrintingBai, Ling; Xie, Zhuoying; Wang, Wei; Yuan, Chunwei; Zhao, Yuanjin; Mu, Zhongde; Zhong, Qifeng; Gu, ZhongzeACS Nano (2014), 8 (11), 11094-11100CODEN: ANCAC3; ISSN:1936-0851. (American Chemical Society)Facile, fast, and cost-effective technol. for patterning of responsive colloidal photonic crystals (CPCs) is of great importance for their practical applications. In this report, we develop a kind of responsive CPC patterns with multicolor shifting properties by ink-jet printing mesoporous colloidal nanoparticle ink on both rigid and soft substrates. By adjusting the size and mesopores' proportion of nanoparticles, we can precisely control the original color and vapor-responsive color shift extent of mesoporous CPC. As a consequence, multicolor mesoporous CPCs patterns with complex vapor responsive color shifts or vapor-revealed implicit images are subsequently achieved. The complicated and reversible multicolor shifts of mesoporous CPC patterns are favorable for immediate recognition by naked eyes but hard to copy. This approach is favorable for integration of responsive CPCs with controllable responsive optical properties. Therefore, it is of great promise for developing advanced responsive CPC devices such as anticounterfeiting devices, multifunctional microchips, sensor arrays, or dynamic displays.
- 62Khan, S.; Lorenzelli, L.; Dahiya, R. S. Technologies for Printing Sensors and Electronics over Large Flexible Substrates: A Review IEEE Sens. J. 2015, 15, 3164– 3185 DOI: 10.1109/JSEN.2014.2375203Google ScholarThere is no corresponding record for this reference.
- 63Potyrailo, R. A.; Burns, A.; Surman, C.; Lee, D. J.; McGinniss, E. Multivariable Passive RFID Vapor Sensors: Roll-to-Roll Fabrication on a Flexible Substrate Analyst 2012, 137, 2777– 2781 DOI: 10.1039/c2an16278dGoogle ScholarThere is no corresponding record for this reference.
- 64Peter, C.; Schulz, S.; Barth, M.; Gempp, M.; Rademacher, S.; Wollenstein, J. Low-Cost Roll-to-Roll Colorimetric Gas Sensor System for Fire Detection Transduc. Eurosens. XXVII 2013, 2632– 2635 DOI: 10.1109/Transducers.2013.6627346Google ScholarThere is no corresponding record for this reference.
- 65Cai, Z.; Smith, N. L.; Zhang, J. T.; Asher, S. A. Two-Dimensional Photonic Crystal Chemical and Biomolecular Sensors Anal. Chem. 2015, 87, 5013– 5025 DOI: 10.1021/ac504679nGoogle Scholar65https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2MXmsVemsLs%253D&md5=2adcef93d05efdd31a9a5ba7b6065eb5Two-Dimensional Photonic Crystal Chemical and Biomolecular SensorsCai, Zhongyu; Smith, Natasha L.; Zhang, Jian-Tao; Asher, Sanford A.Analytical Chemistry (Washington, DC, United States) (2015), 87 (10), 5013-5025CODEN: ANCHAM; ISSN:0003-2700. (American Chemical Society)A review. The authors review recent progress in the development of two-dimensional (2-D) photonic crystal (PC) materials for chem. and biol. sensing applications. Self-assembly methods were developed in the authors' lab. to fabricate 2-D particle array monolayers on mercury and water surfaces. These hexagonal arrays strongly forward Bragg diffract light to report on their array spacings. By embedding these 2-D arrays onto responsive hydrogel surfaces, 2-D PC sensing materials can be fabricated. The 2-D PC sensors use responsive polymer hydrogels that are chem. functionalized to show vol. phase transitions in selective response to particular chem. species. Novel hydrogels were also developed in the authors' lab. by crosslinking proteins while preserving their native structures to maintain their selective binding affinities. The vol. phase transitions swell or shrink the hydrogels, which alter their 2-D array spacings, and shift their diffraction wavelengths. These shifts can be visually detected or spectrally measured. These 2-D PC sensing materials have been used for the detection of many analytes, such as pH, surfactants, metal ions, proteins, anionic drugs, and ammonia. The authors are exploring the use of organogels that use low vapor pressure ionic liqs. as their mobile phases for sensing atm. analytes.
- 66Zhang, C.; Chen, P.; Dong, H.; Zhen, Y.; Liu, M.; Hu, W. Porphyrin Supramolecular 1D Structures Via Surfactant-Assisted Self-Assembly Adv. Mater. 2015, 27, 5379– 5387 DOI: 10.1002/adma.201501273Google Scholar66https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2MXhtFOrt7zM&md5=7f0ec6d1cb562668f820af304cf88885Porphyrin Supramolecular 1D Structures via Surfactant-Assisted Self-AssemblyZhang, Congcong; Chen, Penglei; Dong, Huanli; Zhen, Yonggang; Liu, Minghua; Hu, WenpingAdvanced Materials (Weinheim, Germany) (2015), 27 (36), 5379-5387CODEN: ADVMEW; ISSN:0935-9648. (Wiley-VCH Verlag GmbH & Co. KGaA)A review. One-dimensional (1D) solid-state supramol. structures based on porphyrin chromophores arouse numerous expectations from the interdisciplinary scientific communities of supramol. chem. and advanced soft materials science. This stems from the intrinsic assembly capability of porphyrins to form various well-defined 1D assemblies, which have broad opportunities in the fields of advanced soft matter. A brief review on 1D porphyrin micro-/nanoassemblies constructed via surfactant-assisted self-assembly is presented here, in terms of addressing new ideas recently developed for controlled assembly, hierarchical organization, and new-type functional surfactants etc. The functionalization of the as-assembled 1D structures with regard to supramol. photocatalysis, nonlinear optics, nanoelectronic gas sensors, photoelectrochem. solar cells, etc. is highlighted.
- 67Santos, A.; Deen, M. J.; Marsal, L. F. Low-Cost Fabrication Technologies for Nanostructures: State-of-the-Art and Potential Nanotechnology 2015, 26, 042001 DOI: 10.1088/0957-4484/26/4/042001Google Scholar67https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A280%3ADC%252BC2MvktlWkuw%253D%253D&md5=f6301b2ff11c792b2a4233d24af43cedLow-cost fabrication technologies for nanostructures: state-of-the-art and potentialSantos A; Deen M J; Marsal L FNanotechnology (2015), 26 (4), 042001 ISSN:.In the last decade, some low-cost nanofabrication technologies used in several disciplines of nanotechnology have demonstrated promising results in terms of versatility and scalability for producing innovative nanostructures. While conventional nanofabrication technologies such as photolithography are and will be an important part of nanofabrication, some low-cost nanofabrication technologies have demonstrated outstanding capabilities for large-scale production, providing high throughputs with acceptable resolution and broad versatility. Some of these nanotechnological approaches are reviewed in this article, providing information about the fundamentals, limitations and potential future developments towards nanofabrication processes capable of producing a broad range of nanostructures. Furthermore, in many cases, these low-cost nanofabrication approaches can be combined with traditional nanofabrication technologies. This combination is considered a promising way of generating innovative nanostructures suitable for a broad range of applications such as in opto-electronics, nano-electronics, photonics, sensing, biotechnology or medicine.
- 68Wang, Z. L. Self-Powered Nanosensors and Nanosystems Adv. Mater. 2012, 24, 280– 285 DOI: 10.1002/adma.201102958Google Scholar68https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC3MXhsVKgtLnI&md5=6e6ca07643c31b5ab3d12062567cab35Self-Powered Nanosensors and NanosystemsWang, Zhong LinAdvanced Materials (Weinheim, Germany) (2012), 24 (2), 280-285CODEN: ADVMEW; ISSN:0935-9648. (Wiley-VCH Verlag GmbH & Co. KGaA)A review. Sensor networks are a key technol. and economic driver for global industries in the near future, with applications in health care, environmental monitoring, infrastructure monitoring, national security, and more. Developing technologies for self-powered nanosensors is vitally important. This paper gives a brief summary about recent progress in the area, describing nanogenerators that are capable of providing sustainable self-sufficient micro/nanopower sources for future sensor networks.
- 69Zhou, G.; Huang, L.; Li, W.; Zhu, Z. Harvesting Ambient Environmental Energy for Wireless Sensor Networks: A Survey J. Sens. 2014, 2014, 815467 DOI: 10.1155/2014/815467Google ScholarThere is no corresponding record for this reference.
- 70Misra, V.; Bozkurt, A.; Calhoun, B.; Jackson, T.; Jur, J. S.; Lach, J.; Lee, B.; Muth, J.; Oralkan, O.; Ozturk, M.; Trolier-McKinstry, S.; Vashaee, D.; Wentzloff, D.; Zhu, Y. Flexible Technologies for Self-Powered Wearable Health and Environmental Sensing Proc. IEEE 2015, 103, 665– 681 DOI: 10.1109/JPROC.2015.2412493Google Scholar70https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2MXhtVOis7nE&md5=35168678555be26160be98b6d38dbb1aFlexible technologies for self-powered wearable health and environmental sensingMisra, Veena; Bozkurt, Alper; Calhoun, Benton; Jackson, Thomas; Jur, Jesse; Lach, John; Lee, Bongmook; Muth, John; Oralkan, Oemer; Oeztuerk, Mehmet; Trolier-McKinstry, Susan; Vashaee, Daryoosh; Wentzloff, David; Zhu, YongProceedings of the IEEE (2015), 103 (4), 665-681CODEN: IEEPAD; ISSN:0018-9219. (Institute of Electrical and Electronics Engineers)This article provides the latest advances from the NSF Advanced Self-powered Systems of Integrated sensors and Technologies (ASSIST) center. The work in the center addresses the key challenges in wearable health and environmental systems by exploring technologies that enable ultra-long battery lifetime, user comfort and wearability, robust medically validated sensor data with value added from multimodal sensing, and access to open architecture data streams. The vision of the ASSIST center is to use nanotechnol. to build miniature, self-powered, wearable, and wireless sensing devices that can enable monitoring of personal health and personal environmental exposure and enable correlation of multimodal sensors. These devices can empower patients and doctors to transition from managing illness to managing wellness and create a paradigm shift in improving healthcare outcomes. This article presents the latest advances in high-efficiency nanostructured energy harvesters and storage capacitors, new sensing modalities that consume less power, low power computation, and communication strategies, and novel flexible materials that provide form, function, and comfort. These technologies span a spatial scale ranging from underlying materials at the nanoscale to body worn structures, and the challenge is to integrate them into a unified device designed to revolutionize wearable health applications.
- 71Baranov, A.; Spirjakin, D.; Akbari, S.; Somov, A. Optimization of Power Consumption for Gas Sensor Nodes: A Survey Sens. Actuators, A 2015, 233, 279– 289 DOI: 10.1016/j.sna.2015.07.016Google Scholar71https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2MXhtlSis7nI&md5=e32cfb0251b4f86a99e49c6e9403aeafOptimization of power consumption for gas sensor nodes: A surveyBaranov, Alexander; Spirjakin, Denis; Akbari, Saba; Somov, AndreySensors and Actuators, A: Physical (2015), 233 (), 279-289CODEN: SAAPEB; ISSN:0924-4247. (Elsevier B.V.)The Wireless Sensor Network (WSN) technol. has recently been used, rather successfully, in a huge no. of monitoring applications. However, the monitoring of combustible gases with WSN stands out from typical applications where the wireless communications function is much more power hungry than the sensing one. The reason behind this "dissonance" is in using catalytic or semiconductor sensors that ensure a trade-off among the safety requirements, performance and power consumption. This work provides a survey of intrinsic power optimization techniques with a special focus on recent advances in power management, sensor fabrication, sensing circuits, and measurement procedures. The paper concludes with providing a future outlook in the area.
- 72Forsström, S.; Kanter, T. Enabling Ubiquitous Sensor-Assisted Applications on the Internet-of-Things Pers. Ubiquit. Comput. 2014, 18, 977– 986 DOI: 10.1007/s00779-013-0712-9Google ScholarThere is no corresponding record for this reference.
- 73Yamagiwa, H.; Sato, S.; Fukawa, T.; Ikehara, T.; Maeda, R.; Mihara, T.; Kimura, M. Detection of Volatile Organic Compounds by Weight-Detectable Sensors Coated with Metal-Organic Frameworks Sci. Rep. 2014, 4, 6247 DOI: 10.1038/srep06247Google Scholar73https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2MXksVyktLo%253D&md5=12e05eb734f448e0321f8239ee602fa7Detection of Volatile Organic Compounds by Weight-Detectable Sensors coated with Metal-Organic FrameworksYamagiwa, Hiroki; Sato, Seiko; Fukawa, Tadashi; Ikehara, Tsuyoshi; Maeda, Ryutaro; Mihara, Takashi; Kimura, MutsumiScientific Reports (2014), 4 (), 6247CODEN: SRCEC3; ISSN:2045-2322. (Nature Publishing Group)Detection of volatile org. compds. (VOCs) using wt.-detectable quartz microbalance and silicon-based microcantilever sensors coated with cryst. metal-org. framework (MOF) thin films is described in this paper. The thin films of two MOFs were grown from COOH-terminated self-assembled monolayers onto the gold electrodes of sensor platforms. The MOF layers worked as the effective concentrators of VOC gases, and the adsorption/desorption processes of the VOCs could be monitored by the frequency changes of wt.-detectable sensors. Moreover, the MOF layers provided VOC sensing selectivity to the wt.-detectable sensors through the size-selective adsorption of the VOCs within the regulated nanospace of the MOFs.
- 74Potyrailo, R. A.; Larsen, M.; Riccobono, O. Detection of Individual Vapors and Their Mixtures Using a Selectivity-Tunable Three-Dimensional Network of Plasmonic Nanoparticles Angew. Chem., Int. Ed. 2013, 52, 10360– 10364 DOI: 10.1002/anie.201305303Google Scholar74https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC3sXht1Crur%252FJ&md5=4b4539dff07906eda23c76841d4b0526Detection of Individual Vapors and Their Mixtures Using a Selectivity-Tunable Three-Dimensional Network of Plasmonic NanoparticlesPotyrailo, Radislav A.; Larsen, Michael; Riccobono, OrrieAngewandte Chemie, International Edition (2013), 52 (39), 10360-10364CODEN: ACIEF5; ISSN:1433-7851. (Wiley-VCH Verlag GmbH & Co. KGaA)In this study, we achieved selective detection of not only individual vapors but also their mixts. using a single sensing material [1-mercapto-(triethylene glycol) Me ether functionalized gold nanoparticles] and its localized surface plasmon resonance (LSPR) spectroscopic readout. While LSPR detection of individual vapors has been shown with plasmonic nanoparticles, we demonstrate detection of vapor mixts. with a single LSPR sensing film. To achieve this attractive capability, instead of using a two-dimensional (2D) arrangement of surface-attached plasmonic nanoparticles, we implemented a 3D network of dispersed plasmonic nanoparticles functionalized with a soft vapor-sorbing ligand shell and coupled its LSPR response with multivariate spectral anal.
- 75Cho, B.; Kim, A. R.; Park, Y.; Yoon, J.; Lee, Y. J.; Lee, S.; Yoo, T. J.; Kang, C. G.; Lee, B. H.; Ko, H. C.; Kim, D. H.; Hahm, M. G. Bifunctional Sensing Characteristics of Chemical Vapor Deposition Synthesized Atomic-Layered MoS2 ACS Appl. Mater. Interfaces 2015, 7, 2952– 2959 DOI: 10.1021/am508535xGoogle Scholar75https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2MXmvVOisA%253D%253D&md5=dc9fe6719c97cb2525511958df92b42eBifunctional Sensing Characteristics of Chemical Vapor Deposition Synthesized Atomic-Layered MoS2Cho, Byungjin; Kim, Ah Ra; Park, Youngjin; Yoon, Jongwon; Lee, Young-Joo; Lee, Sangchul; Yoo, Tae Jin; Kang, Chang Goo; Lee, Byoung Hun; Ko, Heung Cho; Kim, Dong-Ho; Hahm, Myung GwanACS Applied Materials & Interfaces (2015), 7 (4), 2952-2959CODEN: AAMICK; ISSN:1944-8244. (American Chemical Society)Two-dimensional (2D) molybdenum disulfide (MoS2) at. layers have a strong potential to be adopted for 2-dimensional electronic components due to extraordinary and novel properties not available in their bulk foams. Unique properties of the MoS2, including quasi-2D crystallinity, ultrahigh surface-to-vol., and a high absorption coeff., have enabled high-performance sensor applications. However, implementation of only a single-functional sensor presents a limitation for various advanced multifunctional sensor applications within a single device. Here, the authors demonstrate the charge-transfer-based sensitive (detection of 120 ppb of NO2) and selective gas-sensing capability of the CVD synthesized MoS2 and good photosensing characteristics, including moderate photoresponsivity (∼71 mA/W), reliable photoresponse, and rapid photoswitching ( < 500 ms). A bifunctional sensor within a single MoS2 device to detect photons and gas mols. in sequence is finally demonstrated, paving a way toward a versatile sensing platform for a futuristic multifunctional sensor.
- 76Grate, J. W. Hydrogen-Bond Acidic Polymers for Chemical Vapor Sensing Chem. Rev. 2008, 108, 726– 745 DOI: 10.1021/cr068109yGoogle Scholar76https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD1cXhtVait7c%253D&md5=e32330bcbedd5e9caddd5eee0428e181Hydrogen-bond acidic polymers for chemical vapor sensingGrate, Jay W.Chemical Reviews (Washington, DC, United States) (2008), 108 (2), 726-745CODEN: CHREAY; ISSN:0009-2665. (American Chemical Society)A review is given for background of sensors and responses, fluorinated alcs. and phenols, fluoroalc.-contg. org. polymers, silicon-based fluoroalc. and fluorinated-phenol polymers, linear solvation energy relationships, acoustic wave sensors and arrays, microcantilever sensors, sensors responding to elec. properties, optical and luminescent sensors, sepns. and preconcn.
- 77Sugiyasu, K.; Swager, T. M. Conducting-Polymer-Based Chemical Sensors: Transduction Mechanisms Bull. Chem. Soc. Jpn. 2007, 80, 2074– 2083 DOI: 10.1246/bcsj.80.2074Google Scholar77https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD2sXhtl2jur7K&md5=fe1e8023cebdf523bab48432ad0d3bd9Conducting-polymer-based chemical sensors: transduction mechanismsSugiyasu, Kazunori; Swager, Timothy M.Bulletin of the Chemical Society of Japan (2007), 80 (11), 2074-2083CODEN: BCSJA8; ISSN:0009-2673. (Chemical Society of Japan)A review. Conducting org. polymers, esp., polythiophene and substituted polythiophenes, for use as sensor materials are discussed. The charge transport mechanisms and response toward analytes based on functional groups and charge interactions are outlined. Sensor systems based on triaryl-Me carbocations are described. The design of specific mol. recognition centers to impart selectivity and the nature of the conducting polymer are also discussed.
- 78Li, B.; Santhanam, S.; Schultz, L.; Jeffries-EL, M.; Iovu, M. C.; Sauvé, G.; Cooper, J.; Zhang, R.; Revelli, J. C.; Kusne, A. G.; Snyder, J. L.; Kowalewski, T.; Weiss, L. E.; McCullough, R. D.; Fedder, G. K.; Lambeth, D. N. Inkjet Printed Chemical Sensor Array Based on Polythiophene Conductive Polymers Sens. Actuators, B 2007, 123, 651– 660 DOI: 10.1016/j.snb.2006.09.064Google Scholar78https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD2sXkvFOgurc%253D&md5=18b546f3c77a562e169d8514910cc079Inkjet printed chemical sensor array based on polythiophene conductive polymersLi, Bo; Santhanam, Suresh; Schultz, Lawrence; Jeffries-El, Malika; Iovu, Mihaela C.; Sauve, Genevieve; Cooper, Jessica; Zhang, Rui; Revelli, Joseph C.; Kusne, Aaron G.; Snyder, Jay L.; Kowalewski, Tomasz; Weiss, Lee E.; McCullough, Richard D.; Fedder, Gary K.; Lambeth, David N.Sensors and Actuators, B: Chemical (2007), 123 (2), 651-660CODEN: SABCEB; ISSN:0925-4005. (Elsevier B.V.)Multiple regioregular polythiophene polymers with a variety of side chains, end groups and secondary polymer chains were used as active sensing layers in a single chip chemresistor sensor array device. A custom inkjet system was used to selectively deposit the polymers onto the array of transduction electrodes. The sensor demonstrated sensitivity and selectivity for detection and discrimination of volatile org. compds. (VOCs). The cond. responses to VOC vapors are dependent on the chem. structure of the polymers. For certain VOCs, cond. increased in some polymers, while it decreased in others. Principal component anal. (PCA) of sensor responses was used to discriminate between the tested VOCs. These results are correlated to the chem. structures of the different polymers, and qual. hypothesis of chem. sensing mechanisms are proposed. This research demonstrates the potential for using such devices in VOC detection and discrimination sensing applications.
- 79Di Natale, C.; Paolesse, R.; D’Amico, A. Metalloporphyrins Based Artificial Olfactory Receptors Sens. Actuators, B 2007, 121, 238– 246 DOI: 10.1016/j.snb.2006.09.038Google Scholar79https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD2sXhtValur8%253D&md5=ac4449896da1adc1cb4c92086fb8706cMetalloporphyrins based artificial olfactory receptorsDi Natale, Corrado; Paolesse, Roberto; D'Amico, ArnaldoSensors and Actuators, B: Chemical (2007), 121 (1), 238-246CODEN: SABCEB; ISSN:0925-4005. (Elsevier B.V.)A review. Metalloporphyrins offer almost unique opportunities to design artificial receptors for chem. sensors. These mols. can be tailored, at the synthetic level, changing in a almost controlled way the sensor selectivity that can be oriented toward desired analyte families. Optical and electrochem. properties of metalloporphyrins are known since several years and they were adequately exploited as potentiometric sensors for ions in solns. In gas sensing the optical characteristics were utilized to detect gases like O2 and NO2 for which metalloporphyrins have a good selectivity. In gas environment, beside these gases the interactions are very rich but rather unselective, nonetheless this feature is interesting for artificial olfaction where a certain degree of cross-selectivity is required. As a consequence, arrays of gas sensors based on metalloporphyrins and optical and mass transducers were demonstrated in the last decade. In this paper the properties of such arrays are reviewed evidencing the high flexibility of such sensors and their wide spectrum of applications.
- 80Pirondini, L.; Dalcanale, E. Molecular Recognition at the Gas-Solid Interface: A Powerful Tool for Chemical Sensing Chem. Soc. Rev. 2007, 36, 695– 706 DOI: 10.1039/B516256BGoogle Scholar80https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD2sXkslClt7k%253D&md5=58bdef046c3f852816bde99ab20ddcaaMolecular recognition at the gas-solid interface: a powerful tool for chemical sensingPirondini, Laura; Dalcanale, EnricoChemical Society Reviews (2007), 36 (5), 695-706CODEN: CSRVBR; ISSN:0306-0012. (Royal Society of Chemistry)A review. This tutorial review deals with the design of mol. receptors capable of mol. recognition at the gas-solid interface, to be used as selective layers in gas sensors. The key issue of specific vs. nonspecific binding in the solid layer is discussed in terms of cavity inclusion and layer morphol. The combined use of mass spectrometry and crystal structure anal. provide accurate information on type, no., geometry and strength of receptor-analyte interactions in the gas phase and in the solid state. The gas sensing properties of a given receptor toward a single class of analytes can be anticipated.
- 81Pinalli, R.; Suman, M.; Dalcanale, E. Cavitands at Work: From Molecular Recognition to Supramolecular Sensors Eur. J. Org. Chem. 2004, 2004, 451– 462 DOI: 10.1002/ejoc.200300430Google ScholarThere is no corresponding record for this reference.
- 82Yan, Y.; Bein, T. Molecular Recognition on Acoustic Wave Devices: Sorption in Chemically Anchored Zeolite Monolayers J. Phys. Chem. 1992, 96, 9387– 9393 DOI: 10.1021/j100202a060Google ScholarThere is no corresponding record for this reference.
- 83Metal-Organic Frameworks: Design and Application; MacGillivray, L. R., Ed.; Wiley: Hoboken, NJ, 2010.Google ScholarThere is no corresponding record for this reference.
- 84Kreno, L. E.; Leong, K.; Farha, O. K.; Allendorf, M.; Van Duyne, R. P.; Hupp, J. T. Metal-Organic Framework Materials as Chemical Sensors Chem. Rev. 2012, 112, 1105– 1125 DOI: 10.1021/cr200324tGoogle Scholar84https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC3MXhsVCgtL%252FI&md5=f6ed572725bc067ee8da81880bf1ec90Metal-Organic Framework Materials as Chemical SensorsKreno, Lauren E.; Leong, Kirsty; Farha, Omar K.; Allendorf, Mark; Van Duyne, Richard P.; Hupp, Joseph T.Chemical Reviews (Washington, DC, United States) (2012), 112 (2), 1105-1125CODEN: CHREAY; ISSN:0009-2665. (American Chemical Society)A review. The authors present a crit. review of the literature on metal-org. frameworks (MOFs) as chem. sensors. The authors begin by briefly examg. challenges relating to MOF sensor development including the design of MOFs with desirable properties, incorporation of appropriate signal transduction capabilities, and integration of MOFs into devices by employing thin-film growth techniques. Subsequent sections discuss specific examples of MOF sensors, categorized by method of signal transduction. Sensors based on MOF photoluminescence are discussed briefly. The authors have limited the review of luminescence-based sensors to a small no. of recent reports where the porous MOF architecture, or its chem. compn., imparts selective sensing capabilities. Scintillating MOFs that luminesce in the presence of radioactive analytes are also discussed. Other signal transduction schemes that use photons include various kinds of optical interferometry, analyte modulation of localized surface plasmon resonance energies, and solvatochromism. Mech. signal-transduction schemes employed with MOFs include ones based on surface acoustic wave, quartz crystal microbalance, and microcantilever devices. Elec. schemes thus far were limited to ones based on impedance spectroscopy.
- 85Göpel, W. Chemisorption and Charge Transfer at Ionic Semiconductor Surfaces: Implications in Designing Gas Sensors Prog. Surf. Sci. 1985, 20, 9– 103 DOI: 10.1016/0079-6816(85)90004-8Google ScholarThere is no corresponding record for this reference.
- 86Korotcenkov, G. Metal Oxides for Solid-State Gas Sensors: What Determines Our Choice? Mater. Sci. Eng., B 2007, 139, 1– 23 DOI: 10.1016/j.mseb.2007.01.044Google Scholar86https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD2sXkt1Cju7s%253D&md5=19280e2cb6316b0e2cd6791e49f23903Metal oxides for solid-state gas sensors: What determines our choice?Korotcenkov, G.Materials Science & Engineering, B: Solid-State Materials for Advanced Technology (2007), 139 (1), 1-23CODEN: MSBTEK; ISSN:0921-5107. (Elsevier B.V.)A review. The anal. of various parameters of metal oxides and the search of criteria, which could be used during material selection for solid-state gas sensor applications, are the main objectives of this review. For these purposes the correlation between electro-phys. (band gap, electrocond., type of cond., oxygen diffusion), thermodn., surface, electronic, structural properties, catalytic activity and gas-sensing characteristics of metal oxides designed for solid-state sensors was established. .It is discussed the role of metal oxide manufacturability, chem. activity, and parameter's stability in sensing material choice as well.
- 87Kim, I.-D.; Rothschild, A.; Tuller, H. L. Advances and New Directions in Gas-Sensing Devices Acta Mater. 2013, 61, 974– 1000 DOI: 10.1016/j.actamat.2012.10.041Google Scholar87https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC3sXhtFahtbo%253D&md5=26c57ce08bb371efb2898239e759eb0eAdvances and new directions in gas-sensing devicesKim, Il-Doo; Rothschild, Avner; Tuller, Harry L.Acta Materialia (2013), 61 (3), 974-1000CODEN: ACMAFD; ISSN:1359-6454. (Elsevier Ltd.)A review. Gas sensors are employed in many applications including detection of toxic and combustible gases, monitoring emissions from vehicles and other combustion processes, breath anal. for medical diagnosis, and quality control in the chems., food and cosmetics industries. Many of these applications employ miniaturized solid-state devices, whose elec. properties change in response to the introduction of chem. analytes into the surrounding gas phase. Key challenges remain as to how to optimize sensor sensitivity, selectivity, speed of response and stability. The principles of operation of such devices vary and a brief review of operating principles based on potentiometric/amperometric, chemisorptive, redox, field effect and nanobalance approaches is presented. Due to simplicity of design and ability to stand up to harsh environments, metal oxide-based chemoresistive devices are commonly selected for these purposes and are therefore the focus of this review. While many studies were published on the operation of such devices, an understanding of the underlying physicochem. principles behind their operation have trailed behind their technol. development. In this article, a detailed review is provided which serves to update progress made along these lines. The introduction of nanodimensioned materials has had a particularly striking impact on the field over the past decade. Advances in materials processing has enabled the fabrication of tailored structures and morphologies offering, at times, orders of magnitude improvements in sensitivity, while high-resoln. anal. methods have enabled a much improved examn. of the structure and chem. of these materials. Selected examples, illustrating the type of nanostructured devices being fabricated and tested, are discussed. This review concludes by highlighting trends suggesting directions for future progress.
- 88Grate, J. W.; Nelson, D. A.; Skaggs, R. Sorptive Behavior of Monolayer-Protected Gold Nanoparticle Films: Implications for Chemical Vapor Sensing Anal. Chem. 2003, 75, 1868– 1879 DOI: 10.1021/ac0206364Google Scholar88https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD3sXitF2qt7w%253D&md5=7f7b57a729968fbb70a978b94eaf4fe0Sorptive behavior of monolayer-protected gold nanoparticle films: Implications for chemical vapor sensingGrate, Jay W.; Nelson, David A.; Skaggs, RhondaAnalytical Chemistry (2003), 75 (8), 1868-1879CODEN: ANCHAM; ISSN:0003-2700. (American Chemical Society)Monolayer-protected gold nanoparticle materials were synthesized and characterized for use as sorptive layers on chem. sensors. Thiols studied as monolayer-forming mols. included dodecanethiol, benzenethiol, 4-chlorobenzenethiol, 4-bromobenzenethiol, 4-(trifluoromethyl)benzenethiol, 4-hydroxybenzenethiol, and 4-aminobenzenethiol. Films of selected monolayer-protected nanoparticle (MPN) materials were deposited on thickness shear mode devices and vapor uptake properties were measured at 298 K. Many, but not all, MPN-based sensing layers demonstrated rapid and reversible uptake of vapors, and sorptive selectivity varies with the monolayer structure. The mass of vapor sorbed per mass of sorptive material was detd. and compared with poly(isobutylene) and poly(epichlorohydrin) as examples of simple sorptive polymers that were used on vapor sensors. The nanoparticle-based films considered here were less sorptive than the selected polymers on a per-mass basis. Partition coeffs., which measure the mass of vapor sorbed per vol. of the sorptive phase, were estd. for these MPN materials and are comparable to or less than those of the polymer layers. Implications for the roles of sorption and transduction in detg. the performance of chem. sensors coated with nanoparticle-based films are discussed.
- 89Steinecker, W. H.; Rowe, M. P.; Zellers, E. T. Model of Vapor-Induced Resistivity Changes in Gold-Thiolate Monolayer-Protected Nanoparticle Sensor Films Anal. Chem. 2007, 79, 4977– 4986 DOI: 10.1021/ac070068yGoogle Scholar89https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD2sXls1Krtb0%253D&md5=61f3b4aec00cf1cce624ee1c823e33e3Model of Vapor-Induced Resistivity Changes in Gold-Thiolate Monolayer-Protected Nanoparticle Sensor FilmsSteinecker, William H.; Rowe, Michael P.; Zellers, Edward T.Analytical Chemistry (Washington, DC, United States) (2007), 79 (13), 4977-4986CODEN: ANCHAM; ISSN:0003-2700. (American Chemical Society)A study of the modulation of charge transport through thin films of n-octanethiolate monolayer-protected gold nanoparticles (MPN) induced by the sorption of org. vapors is presented. A model is derived that allows predictions of MPN-coated chemiresistor (CR) responses from vapor-film partition coeffs., and analyte densities and dielec. consts. Calibrations with vapors of 28 compds. collected from an array of CRs and a parallel thickness-shear-mode resonator are used to verify assumptions inherent in the model and to assess its performance. Results afford insights into the nature of the vapor-MPN interactions, including systematic variations in apparent film swelling efficiencies, and show that the model can predict CR responses typically to within 24%. Using CRs of different dimensions, vapor sensitivities are virtually independent of the MPN film vol. over a range of 104 (device-area × MPN layer thickness). Sensitivities vary inversely with analyte vapor pressure similarly for the two sensor types, but the CR sensor affords significantly greater signal-to-noise ratios, yielding calcd. detection limits in the low-part-per-billion concn. range for several of the analytes tested. The implications of these results for implementing MPN-coated CR arrays as detectors in microanal. systems are considered.
- 90Snow, E. S.; Perkins, F. K.; Houser, E. J.; Badescu, S. C.; Reinecke, T. L. Chemical Detection with a Single-Walled Carbon Nanotube Capacitor Science 2005, 307, 1942– 1945 DOI: 10.1126/science.1109128Google Scholar90https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD2MXisVyitbg%253D&md5=ac747f523eba9ee0029e0d616f3eb23cChemical Detection with a Single-Walled Carbon Nanotube CapacitorSnow, E. S.; Perkins, F. K.; Houser, E. J.; Badescu, S. C.; Reinecke, T. L.Science (Washington, DC, United States) (2005), 307 (5717), 1942-1945CODEN: SCIEAS; ISSN:0036-8075. (American Association for the Advancement of Science)The capacitance of single-walled C nanotubes (SWNTs) is highly sensitive to a broad class of chem. vapors and this transduction mechanism can form the basis for a fast, low-power sorption-based chem. sensor. In the presence of a dil. chem. vapor, mol. adsorbates are polarized by the fringing elec. fields radiating from the surface of a SWNT electrode, which causes an increase in its capacitance. The authors use this effect to construct a high-performance chem. sensor by thinly coating the SWNTs with chemoselective materials that provide a large, class-specific gain to the capacitance response. Such SWNT chemicapacitors are fast, highly sensitive, and completely reversible.
- 91Bondavalli, P.; Legagneux, P.; Pribat, D. Carbon Nanotubes Based Transistors as Gas Sensors: State of the Art and Critical Review Sens. Actuators, B 2009, 140, 304– 318 DOI: 10.1016/j.snb.2009.04.025Google Scholar91https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD1MXmvFajsbY%253D&md5=8abf26505c4ad51c1932b4844848d5ecCarbon nanotubes based transistors as gas sensors: State of the art and critical reviewBondavalli, Paolo; Legagneux, Pierre; Pribat, DidierSensors and Actuators, B: Chemical (2009), 140 (1), 304-318CODEN: SABCEB; ISSN:0925-4005. (Elsevier B.V.)A review. In this paper we present recent studies concerning gas sensors based on carbon nanotube field effect transistors (CNTFETs). Although these devices have allowed one to realize sensors with an impressive sensitivity compared to existing technologies, the phys. interpretation of the interaction between the gas mols. and the CNTFETs has not been clarified yet. In this contribution, we try to find some consistency between the phys. interpretations advanced by the different scientific teams working on the subject and to answer some unsolved questions. Moreover, considering that the selectivity is the main issue, we analyze the different routes that have been proposed to overcome this problem: functionalization using polymers, diversification of the source/drain metal electrodes, metal decoration of SWCNT mats, exploitation of the desorption time of the different gases. For each technique we try to evaluate the advantages and the drawbacks.
- 92Schedin, F.; Geim, A. K.; Morozov, S. V.; Hill, E. W.; Blake, P.; Katsnelson, M. I.; Novoselov, K. S. Detection of Individual Gas Molecules Adsorbed on Graphene Nat. Mater. 2007, 6, 652– 655 DOI: 10.1038/nmat1967Google Scholar92https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD2sXpvFKjsrs%253D&md5=dedbfc7b95a13316bcbb8ebc5956c1d3Detection of individual gas molecules adsorbed on grapheneSchedin, F.; Geim, A. K.; Morozov, S. V.; Hill, E. W.; Blake, P.; Katsnelson, M. I.; Novoselov, K. S.Nature Materials (2007), 6 (9), 652-655CODEN: NMAACR; ISSN:1476-1122. (Nature Publishing Group)Authors show that micrometre-size sensors made from graphene are capable of detecting individual events when a gas mol. attaches to or detaches from graphene's surface. The adsorbed mols. change the local carrier concn. in graphene one by one electron, which leads to step-like changes in resistance. The achieved sensitivity is due to the fact that graphene is an exceptionally low-noise material electronically, which makes it a promising candidate not only for chem. detectors but also for other applications where local probes sensitive to external charge, magnetic field or mech. strain are required.
- 93Perkins, F. K.; Friedman, A. L.; Cobas, E.; Campbell, P. M.; Jernigan, G. G.; Jonker, B. T. Chemical Vapor Sensing with Monolayer MoS2 Nano Lett. 2013, 13, 668– 673 DOI: 10.1021/nl3043079Google Scholar93https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC3sXhtFahsrc%253D&md5=9b9bb82d5691075804da17f0facb1d24Chemical Vapor Sensing with Monolayer MoS2Perkins, F. K.; Friedman, A. L.; Cobas, E.; Campbell, P. M.; Jernigan, G. G.; Jonker, B. T.Nano Letters (2013), 13 (2), 668-673CODEN: NALEFD; ISSN:1530-6984. (American Chemical Society)Two-dimensional materials such as graphene show great potential for future nanoscale electronic devices. The high surface-to-vol. ratio is a natural asset for applications such as chem. sensing, where perturbations to the surface resulting in charge redistribution are readily manifested in the transport characteristics. Single monolayer MoS2 functions effectively as a chem. sensor, exhibiting highly selective reactivity to a range of analytes and providing sensitive transduction of transient surface physisorption events to the conductance of the monolayer channel. Strong response upon exposure to triethylamine, a decompn. product of the V-series nerve gas agents were found. These results in the context of analyte/sensor interaction in which the analyte serves as either an electron donor or acceptor, producing a temporary charge perturbation of the sensor material are discussed. Highly selective response to electron donors and little response to electron acceptors, consistent with the weak n-type character of the authors' MoS2 were found. The MoS2 sensor exhibits a much higher selectivity than carbon nanotube-based sensors.
- 94Cho, B.; Hahm, M. G.; Choi, M.; Yoon, J.; Kim, A. R.; Lee, Y. J.; Park, S. G.; Kwon, J. D.; Kim, C. S.; Song, M.; Jeong, Y.; Nam, K. S.; Lee, S.; Yoo, T. J.; Kang, C. G.; Lee, B. H.; Ko, H. C.; Ajayan, P. M.; Kim, D. H. Charge-Transfer-Based Gas Sensing Using Atomic-Layer MoS2 Sci. Rep. 2015, 5, 8052 DOI: 10.1038/srep08052Google Scholar94https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2MXhtFKju7zJ&md5=d443caad8bd2e5fe3e42e8ebc7df2392Charge-transfer-based Gas Sensing Using Atomic-layer MoS2Cho, Byungjin; Hahm, Myung Gwan; Choi, Minseok; Yoon, Jongwon; Kim, Ah Ra; Lee, Young-Joo; Park, Sung-Gyu; Kwon, Jung-Dae; Kim, Chang Su; Song, Myungkwan; Jeong, Yongsoo; Nam, Kee-Seok; Lee, Sangchul; Yoo, Tae Jin; Kang, Chang Goo; Lee, Byoung Hun; Ko, Heung Cho; Ajayan, Pulickel M.; Kim, Dong-HoScientific Reports (2015), 5 (), 8052CODEN: SRCEC3; ISSN:2045-2322. (Nature Publishing Group)Two-dimensional (2D) molybdenum disulfide (MoS2) at.layers have a strong potential to be used as 2D electronic sensor components. However, intrinsic synthesis challenges have made this task difficult. In addn., the detection mechanisms for gas mols.are not fully understood. Here, we report a high-performance gas sensor constructed using at.-layered MoS2 synthesized by chem.vapor deposition (CVD). A highly sensitive and selective gas sensor based on the CVD-synthesized MoS2 was developed. In situ photoluminescence characterization revealed the charge transfer mechanism between the gas mols.and MoS2, which was validated by theor.calcns. First-principles d.functional theory calcns.indicated that NO2 and NH3 mols.have neg.adsorption energies (i.e., the adsorption processes are exothermic). Thus, NO2 and NH3 mols.are likely to adsorb onto the surface of the MoS2. The in situ PL characterization of the changes in the peaks corresponding to charged trions and neutral excitons via gas adsorption processes was used to elucidate the mechanisms of charge transfer between the MoS2 and the gas mols.
- 95Joy, N. A.; Nandasiri, M. I.; Rogers, P. H.; Jiang, W.; Varga, T.; Kuchibhatla, S. V. N. T.; Thevuthasan, S.; Carpenter, M. A. Selective Plasmonic Gas Sensing: H2, NO2, and CO Spectral Discrimination by a Single Au-CeO2 Nanocomposite Film Anal. Chem. 2012, 84, 5025– 5034 DOI: 10.1021/ac3006846Google Scholar95https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC38XmsFGjtLk%253D&md5=ad4ad04b1244fe1d3522771447c652dbSelective Plasmonic Gas Sensing: H2, NO2, and CO Spectral Discrimination by a Single Au-CeO2 Nanocomposite FilmJoy, Nicholas A.; Nandasiri, Manjula I.; Rogers, Phillip H.; Jiang, Weilin; Varga, Tamas; Kuchibhatla, Satyanarayana V. N. T.; Thevuthasan, Suntharampillai; Carpenter, Michael A.Analytical Chemistry (Washington, DC, United States) (2012), 84 (11), 5025-5034CODEN: ANCHAM; ISSN:0003-2700. (American Chemical Society)A Au-CeO2 nanocomposite film was studied as a potential sensing element for high-temp. plasmonic sensing of H2, CO, and NO2 in an oxygen contg. environment. The CeO2 thin film was deposited by MBE, and Au was implanted into the as-grown film at an elevated temp. followed by high temp. annealing to form well-defined Au nanoclusters. The Au-CeO2 nanocomposite film was characterized by XRD and Rutherford backscattering spectrometry (RBS). For the gas sensing expts., sep. exposures to varying concns. of H2, CO, and NO2 were performed at a temp. of 500° in oxygen backgrounds of 5.0, 10, and ∼21% O2. Changes in the localized surface plasmon resonance (LSPR) absorption peak were monitored during gas exposures and are believed to be the result of oxidn.-redn. processes that fill or create oxygen vacancies in the CeO2. This process affects the LSPR peak position either by charge exchange with the Au nanoparticles (AuNPs) or by changes in the dielec. const. surrounding the particles. Spectral multivariate anal. was used to gauge the inherent selectivity of the film between the sep. analytes. From principal component anal. (PCA), unique and identifiable responses were seen for each of the analytes. Linear discriminant anal. (LDA) was also used and showed sepn. between analytes as well as trends in gas concn. The Au-CeO2 thin film is selective to O2, H2, CO, and NO2 in sep. exposures. This, combined with the obsd. stability over long exposure periods, shows the Au-CeO2 film has good potential as an optical sensing element for harsh environmental conditions.
- 96Potyrailo, R. A.; Ding, Z.; Butts, M. D.; Genovese, S. E.; Deng, T. Selective Chemical Sensing Using Structurally Colored Core-Shell Colloidal Crystal Films IEEE Sens. J. 2008, 8, 815– 822 DOI: 10.1109/JSEN.2008.923191Google Scholar96https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD1cXnvVShtLg%253D&md5=95ee1e59a9bd177eaafc6fb428549659Selective chemical sensing using structurally colored core-shell colloidal crystal filmsPotyrailo, Radislav A.; Ding, Zhebo; Butts, Matthew D.; Genovese, Sarah E.; Deng, TaoIEEE Sensors Journal (2008), 8 (6), 815-822CODEN: ISJEAZ; ISSN:1530-437X. (Institute of Electrical and Electronics Engineers)We demonstrate for the first time selective sensing of multiple vapors at low concns. based on the structurally colored colloidal crystal film formed from composite core/shell nanospheres. Since color changes of sensing colloidal crystal films are negligible at relatively low vapor partial pressures (P/P0 < 0.1), a straightforward detection of color changes cannot be applied. To overcome this limitation, we apply a differential spectroscopy measurement approach coupled with the multivariate anal. of differential reflectance spectra. The vapor-sensing selectivity is provided by the combination of the composite nature of the colloidal nanospheres in the film with the multivariate anal. of the spectral changes of the film reflectivity upon exposure to different vapors. The multianalyte sensing was demonstrated using a colloidal crystal film comprised of 326-nm diam. core polystyrene nanospheres coated with a 20-nm thick sol-gel shell. Discrimination of water, acetonitrile, toluene, and dichloromethane vapors using a single sensing colloidal crystal film was evaluated applying principal components anal. (PCA) of the reflectivity spectra. The polar and nonpolar vapors at different relative vapor partial pressures were well sepd. in PCA space. The best selectivity was obtained between toluene and dichloromethane vapors, while water and acetonitrile vapors were almost unresolved. Achieved detection limits were within the range of interest or better than those needed for detns. of these vapors for industrial applications.
- 97Potyrailo, R. A.; Ghiradella, H.; Vertiatchikh, A.; Dovidenko, K.; Cournoyer, J. R.; Olson, E. Morpho Butterfly Wing Scales Demonstrate Highly Selective Vapour Response Nat. Photonics 2007, 1, 123– 128 DOI: 10.1038/nphoton.2007.2Google Scholar97https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD2sXltVKiu7s%253D&md5=024b55c64df14e75d69d67ee073fd0bdMorpho butterfly wing scales demonstrate highly selective vapour responsePotyrailo, Radislav A.; Ghiradella, Helen; Vertiatchikh, Alexei; Dovidenko, Katharine; Cournoyer, James R.; Olson, EricNature Photonics (2007), 1 (2), 123-128CODEN: NPAHBY; ISSN:1749-4885. (Nature Publishing Group)Tropical Morpho butterflies are famous for their brilliant iridescent colors, which arise from ordered arrays of scales on their wings. Here the authors show that the iridescent scales of the Morpho sulkowskyi butterfly give a different optical response to different individual vapors, and that this optical response dramatically outperforms that of existing nano-engineered photonic sensors. The reflectance spectra of the scales provide information about the nature and concn. of the vapors, allowing the authors to identify a range of closely related vapors- water, methanol, ethanol and isomers of dichloroethylene when they are analyzed individually. By comparing the reflectance as a function of time for different vapors, the authors deduce that wing regions with scale structures of differing spatial periodicity give contributions to the overall spectral response at different wavelengths. The authors' optical model explains the effect of different components of the wing scales on the vapor response, and could steer the design of new man-made optical gas sensors.
- 98Potyrailo, R. A.; Starkey, T.; Vukusic, P.; Ghiradella, H.; Vasudev, M.; Bunning, T.; Naik, R. R.; Tang, Z.; Larsen, M.; Deng, T.; Zhong, S.; Palacios, M.; Grande, J. C.; Zorn, G.; Goddard, G.; Zalubovsky, S. Discovery of the Surface Polarity Gradient on Iridescent Morpho Butterfly Scales Reveals a Mechanism of Their Selective Vapor Response Proc. Natl. Acad. Sci. U. S. A. 2013, 110, 15567– 15572 DOI: 10.1073/pnas.1311196110Google Scholar98https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC3sXhs1WlurrM&md5=e2eb529eb5589ac47928e517b8d3a317Discovery of the surface polarity gradient on iridescent Morpho butterfly scales reveals a mechanism of their selective vapor responsePotyrailo, Radislav A.; Starkey, Timothy A.; Vukusic, Peter; Ghiradella, Helen; Vasudev, Milana; Bunning, Timothy; Naik, Rajesh R.; Tang, Zhexiong; Larsen, Michael; Deng, Tao; Zhong, Sheng; Palacios, Manuel; Grande, James C.; Zorn, Gilad; Goddard, Gregory; Zalubovsky, SergeyProceedings of the National Academy of Sciences of the United States of America (2013), 110 (39), 15567-15572,S15567/1-S15567/9CODEN: PNASA6; ISSN:0027-8424. (National Academy of Sciences)For almost a century, the iridescence of tropical Morpho butterfly scales has been known to originate from 3-dimensional vertical ridge structures of stacked periodic layers of cuticle sepd. by air gaps. Here we describe a biol. pattern of surface functionality that we have found in these photonic structures. This pattern is a gradient of surface polarity of the ridge structures that runs from their polar tops to their less-polar bottoms. This finding shows a biol. pattern design that could stimulate numerous technol. applications ranging from photonic security tags to self-cleaning surfaces, gas separators, protective clothing, sensors, and many others. As an important 1st step, this biomaterial property and our knowledge of its basis has allowed us to unveil a general mechanism of selective vapor response obsd. in the photonic Morpho nanostructures. This mechanism of selective vapor response brings a multivariable perspective for sensing, where selectivity is achieved within a single chem. graded nanostructured sensing unit, rather than from an array of sep. sensors.
- 99Potyrailo, R. A.; Bonam, R. K.; Hartley, J. G.; Starkey, T. A.; Vukusic, P.; Vasudev, M.; Bunning, T.; Naik, R. R.; Tang, Z.; Palacios, M.; Larsen, M.; Le Tarte, L. A.; Grande, J. C.; Deng, T.; Zhong, S. Towards Outperforming Conventional Sensor Arrays with Fabricated Individual Photonic Vapour Sensors Inspired by Morpho Butterflies Nat. Commun. 2015, 6, 7959 DOI: 10.1038/ncomms8959Google Scholar99https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A280%3ADC%252BC287nvVGktw%253D%253D&md5=d85fde77ba7c8b994f19f2817e113a70Towards outperforming conventional sensor arrays with fabricated individual photonic vapour sensors inspired by Morpho butterfliesPotyrailo Radislav A; Tang Zhexiong; Palacios Manuel A; Larsen Michael; Le Tarte Laurie A; Grande James C; Zhong Sheng; Deng Tao; Bonam Ravi K; Hartley John G; Starkey Timothy A; Vukusic Peter; Vasudev Milana; Bunning Timothy; Naik Rajesh R; Vasudev Milana; Deng TaoNature communications (2015), 6 (), 7959 ISSN:.Combining vapour sensors into arrays is an accepted compromise to mitigate poor selectivity of conventional sensors. Here we show individual nanofabricated sensors that not only selectively detect separate vapours in pristine conditions but also quantify these vapours in mixtures, and when blended with a variable moisture background. Our sensor design is inspired by the iridescent nanostructure and gradient surface chemistry of Morpho butterflies and involves physical and chemical design criteria. The physical design involves optical interference and diffraction on the fabricated periodic nanostructures and uses optical loss in the nanostructure to enhance the spectral diversity of reflectance. The chemical design uses spatially controlled nanostructure functionalization. Thus, while quantitation of analytes in the presence of variable backgrounds is challenging for most sensor arrays, we achieve this goal using individual multivariable sensors. These colorimetric sensors can be tuned for numerous vapour sensing scenarios in confined areas or as individual nodes for distributed monitoring.
- 100Rumyantsev, S.; Liu, G.; Shur, M. S.; Potyrailo, R. A.; Balandin, A. A. Selective Gas Sensing with a Single Pristine Graphene Transistor Nano Lett. 2012, 12, 2294– 2298 DOI: 10.1021/nl3001293Google Scholar100https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC38XlsFeksrw%253D&md5=24198204e4b9167494db293cce1a8600Selective Gas Sensing with a Single Pristine Graphene TransistorRumyantsev, Sergey; Liu, Guanxiong; Shur, Michael S.; Potyrailo, Radislav A.; Balandin, Alexander A.Nano Letters (2012), 12 (5), 2294-2298CODEN: NALEFD; ISSN:1530-6984. (American Chemical Society)We show that vapors of different chems. produce distinguishably different effects on the low-frequency noise spectra of graphene. It was found in a systematic study that some gases change the elec. resistance of graphene devices without changing their low-frequency noise spectra while other gases modify the noise spectra by inducing Lorentzian components with distinctive features. The characteristic frequency fc of the Lorentzian noise bulges in graphene devices is different for different chems. and varies from fc = 10-20 Hz to fc = 1300-1600 Hz for THF and chloroform vapors, resp. The obtained results indicate that the low-frequency noise in combination with other sensing parameters can allow one to achieve the selective gas sensing with a single pristine graphene transistor. Our method of gas sensing with graphene does not require graphene surface functionalization or fabrication of an array of the devices with each tuned to a certain chem.
- 101Potyrailo, R. A.Closing the Gap between Existing and Needed Sensors for the Internet-of-Things Applications; Internet of Things Applications USA: Santa Clara, CA, November 19–20, 2014.Google ScholarThere is no corresponding record for this reference.
- 102Potyrailo, R. A.High-Selectivity Sensing Using Tunable Nanomaterials and Multivariable Transducers; Pittsburgh Conf. Anal. Chem. Appl. Spectrosc.: New Orleans, LA, 2015; Paper 1300.Google ScholarThere is no corresponding record for this reference.
- 103Potyrailo, R. A.; Leach, A. M.; Morris, W. G. PDA-Based Multifunctional Microfluidic Sensor System; Proc. IMCS 2012—The 14th Int. Meet. Chem. Sen., Nürnberg, Germany, May 20–23, 2012; Elsevier: 2012; pp 649– 651.Google ScholarThere is no corresponding record for this reference.
- 104Kong, J.; Franklin, N. R.; Zhou, C.; Chapline, M. G.; Peng, S.; Cho, K.; Dai, H. Nanotube Molecular Wires as Chemical Sensors Science 2000, 287, 622– 625 DOI: 10.1126/science.287.5453.622Google Scholar104https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD3cXovVWgtA%253D%253D&md5=0984de88faa1e422a82b73b91c720a5aNanotube molecular wires as chemical sensorsKong, Jing; Franklin, Nathan R.; Zhou, Chongwu; Chapline, Michael G.; Peng, Shu; Cho, Kyeongjae; Dailt, HongjieScience (Washington, D. C.) (2000), 287 (5453), 622-625CODEN: SCIEAS; ISSN:0036-8075. (American Association for the Advancement of Science)Chem. sensors based on individual single-walled C nanotubes (SWNTs) are demonstrated. Upon exposure to gaseous mols. such as NO2 or NH3, the elec. resistance of a semiconducting SWNT dramatically increases or decrease. This serves as the basis for nanotube mol. sensors. The nanotube sensors exhibit a fast response and a substantially higher sensitivity than that of existing solid-state sensors at room temp. Sensor reversibility is achieved by slow recovery under ambient conditions or by heating to high temps. The interactions between mol. species and SWNTs and the mechanisms of mol. sensing with nanotube mol. wires are studied.
- 105Favier, F.; Walter, E. C.; Zach, M. P.; Benter, T.; Penner, R. M. Hydrogen Sensors and Switches from Electrodeposited Palladium Mesowire Arrays Science 2001, 293, 2227– 2231 DOI: 10.1126/science.1063189Google Scholar105https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD3MXntFCrsLo%253D&md5=bfef30603916b8b8ea893f1d65321cfaHydrogen sensors and switches from electrodeposited palladium mesowire arraysFavier, Frederic; Walter, Erich C.; Zach, Michael P.; Benter, Thorsten; Penner, Reginald M.Science (Washington, DC, United States) (2001), 293 (5538), 2227-2231CODEN: SCIEAS; ISSN:0036-8075. (American Association for the Advancement of Science)Hydrogen sensors and hydrogen-activated switches were fabricated from arrays of mesoscopic palladium wires. These palladium mesowire arrays were prepd. by electrodeposition onto graphite surfaces and were transferred onto a cyanoacrylate film. Exposure to hydrogen gas caused a rapid ( < 75 ms) reversible decrease in the resistance of the array that correlated with the hydrogen concn. at 2-10%. The sensor response appears to involve the closing of nanoscopic gaps or break junctions in wires caused by the dilation of palladium grains undergoing hydrogen absorption. Wire arrays in which all wires possessed nanoscopic gaps reverted to open circuits in the absence of hydrogen gas.
- 106Qi, P.; Vermesh, O.; Grecu, M.; Javey, A.; Wang, Q.; Dai, H.; Peng, S.; Cho, K. J. Toward Large Arrays of Multiplex Functionalized Carbon Nanotube Sensors for Highly Sensitive and Selective Molecular Detection Nano Lett. 2003, 3, 347– 351 DOI: 10.1021/nl034010kGoogle Scholar106https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD3sXptlKqtg%253D%253D&md5=e986e310ff6de864c01f97fe297ecc3cToward Large Arrays of Multiplex Functionalized Carbon Nanotube Sensors for Highly Sensitive and Selective Molecular DetectionQi, Pengfei; Vermesh, Ophir; Grecu, Mihai; Javey, Ali; Wang, Qian; Dai, Hongjie; Peng, Shu; Cho, K. J.Nano Letters (2003), 3 (3), 347-351CODEN: NALEFD; ISSN:1530-6984. (American Chemical Society)Arrays of elec. devices with each comprising multiple single-walled carbon nanotubes (SWNT) bridging metal electrodes were obtained by CVD of nanotubes across prefabricated electrode arrays. The ensemble of nanotubes in such a device collectively exhibits large elec. conductance changes under electrostatic gating, owing to the high percentage of semiconducting nanotubes. This leads to the fabrication of large arrays of low-noise elec. nanotube sensors with 100% yield for detecting gas mols. Polymer functionalization was used to impart high sensitivity and selectivity to the sensors. Polyethyleneimine coating affords n-type nanotube devices capable of detecting NO2 at <1 ppb (parts-per-billion) concns. while being insensitive to NH3. Coating Nafion (a polymeric perfluorinated sulfonic acid ionomer) on nanotubes blocks NO2 and allows for selective sensing of NH3. Multiplex functionalization of a nanotube sensor array is carried out by microspotting. Detection of mols. in a gas mixt. is demonstrated with the multiplexed nanotube sensors.
- 107Ma, R. M.; Ota, S.; Li, Y.; Yang, S.; Zhang, X. Explosives Detection in a Lasing Plasmon Nanocavity Nat. Nanotechnol. 2014, 9, 600– 604 DOI: 10.1038/nnano.2014.135Google Scholar107https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2cXhtFygs7vF&md5=ec9e40e649f7f26c7161e5f09f13584cExplosives detection in a lasing plasmon nanocavityMa, Ren-Min; Ota, Sadao; Li, Yimin; Yang, Sui; Zhang, XiangNature Nanotechnology (2014), 9 (8), 600-604CODEN: NNAABX; ISSN:1748-3387. (Nature Publishing Group)Perhaps the most successful application of plasmonics to date has been in sensing, where the interaction of a nanoscale localized field with analytes leads to high-sensitivity detection in real time and in a label-free fashion. However, all previous designs have been based on passively excited surface plasmons, in which sensitivity is intrinsically limited by the low quality factors induced by metal losses. It has recently been proposed theor. that surface plasmon sensors with active excitation (gain-enhanced) can achieve much higher sensitivities due to the amplification of the surface plasmons. Here, we exptl. demonstrate an active plasmon sensor that is free of metal losses and operating deep below the diffraction limit for visible light. Loss compensation leads to an intense and sharp lasing emission that is ultrasensitive to adsorbed mols. We validated the efficacy of our sensor to detect explosives in air under normal conditions and have achieved a sub-part-per-billion detection limit, the lowest reported to date for plasmonic sensors with 2,4-dinitrotoluene and ammonium nitrate. The selectivity between 2,4-dinitrotoluene, ammonium nitrate and nitrobenzene is on a par with other state-of-the-art explosives detectors. Our results show that monitoring the change of the lasing intensity is a superior method than monitoring the wavelength shift, as is widely used in passive surface plasmon sensors. We therefore envisage that nanoscopic sensors that make use of plasmonic lasing could become an important tool in security screening and biomol. diagnostics.
- 108Chen, G.; Paronyan, T. M.; Harutyunyan, A. R. Sub-ppt Gas Detection with Pristine Graphene Appl. Phys. Lett. 2012, 101, 053119 DOI: 10.1063/1.4742327Google Scholar108https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC38XhtFClsLbK&md5=89239dd2148ffd70d0b430f3e480519bSub-ppt gas detection with pristine grapheneChen, Gugang; Paronyan, Tereza M.; Harutyunyan, Avetik R.Applied Physics Letters (2012), 101 (5), 053119/1-053119/4CODEN: APPLAB; ISSN:0003-6951. (American Institute of Physics)Graphene is widely regarded as one of the most promising materials for sensor applications. A pristine graphene can detect gas mols. at extremely low concns. with detection limits as low as 158 parts-per-quadrillion (ppq) for a range of gas mols. at room temp. The unprecedented sensitivity was achieved by applying the author's recently developed concept of continuous in situ cleaning of the sensing material with UV light. The simplicity of the concept, together with graphene's flexibility to be used on various platforms, is expected to intrigue more investigations to develop ever more sensitive sensors. (c) 2012 American Institute of Physics.
- 109Salehi-Khojin, A.; Lin, K. Y.; Field, C. R.; Masel, R. I. Nonthermal Current-Stimulated Desorption of Gases from Carbon Nanotubes Science 2010, 329, 1327– 1330 DOI: 10.1126/science.1194210Google Scholar109https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC3cXhtFajs7rP&md5=1952f9cb2c1b2ecab4c2d00b28fc3411Nonthermal Current-Stimulated Desorption of Gases from Carbon NanotubesSalehi-Khojin, Amin; Lin, Kevin Y.; Field, Christopher R.; Masel, Richard I.Science (Washington, DC, United States) (2010), 329 (5997), 1327-1330CODEN: SCIEAS; ISSN:0036-8075. (American Association for the Advancement of Science)The desorption of gases from carbon nanotubes is usually a slow process that limits the nanotubes' utility as sensors or as memristors. Here, flow in the nanotube above the Poole-Frenkel conduction threshold can stimulate adsorbates to desorb without heating the sensor substantially. The method is general: alcs., aroms., amines, and phosphonates were all found to desorb. The authors postulate that the process is analogous to electron-stimulated desorption, but with an internally conducted rather than externally applied source of electrons.
- 110Borini, S.; White, R.; Wei, D.; Astley, M.; Haque, S.; Spigone, E.; Harris, N.; Kivioja, J.; Ryhänen, T. Ultrafast Graphene Oxide Humidity Sensors ACS Nano 2013, 7, 11166– 11173 DOI: 10.1021/nn404889bGoogle Scholar110https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC3sXhslGgs73P&md5=53b716bdca38a5db5473ca07c4d67ef6Ultrafast Graphene Oxide Humidity SensorsBorini, Stefano; White, Richard; Wei, Di; Astley, Michael; Haque, Samiul; Spigone, Elisabetta; Harris, Nadine; Kivioja, Jani; Ryhanen, TapaniACS Nano (2013), 7 (12), 11166-11173CODEN: ANCAC3; ISSN:1936-0851. (American Chemical Society)Sensors allow an electronic device to become a gateway between the digital and phys. worlds, and sensor materials with unprecedented performance can create new applications and new avenues for user interaction. Graphene oxide can be exploited in humidity and temp. sensors with a no. of convenient features such as flexibility, transparency and suitability for large-scale manufg. Here we show that the two-dimensional nature of graphene oxide and its superpermeability to water combine to enable humidity sensors with unprecedented response speed (∼30 ms response and recovery times). This opens the door to various applications, such as touchless user interfaces, which we demonstrate with a 'whistling' recognition anal.
- 111Kulkarni, G. S.; Reddy, K.; Zhong, Z.; Fan, X. Graphene Nanoelectronic Heterodyne Sensor for Rapid and Sensitive Vapour Detection Nat. Commun. 2014, 5, 4376 DOI: 10.1038/ncomms5376Google Scholar111https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2cXhvF2murzF&md5=a2755b272069111688a241ef87c2b3eaGraphene nanoelectronic heterodyne sensor for rapid and sensitive vapour detectionKulkarni, Girish S.; Reddy, Karthik; Zhong, Zhaohui; Fan, XudongNature Communications (2014), 5 (), 4376CODEN: NCAOBW; ISSN:2041-1723. (Nature Publishing Group)Nearly all existing nanoelectronic sensors are based on charge detection, where mol. binding changes the charge d. of the sensor and leads to sensing signal. However, intrinsically slow dynamics of interface-trapped charges and defect-mediated charge-transfer processes significantly limit those sensors' response to tens to hundreds of seconds, which has long been known as a bottleneck for studying the dynamics of mol.-nanomaterial interaction and for many applications requiring rapid and sensitive response. Here we report a fundamentally different sensing mechanism based on mol. dipole detection enabled by a pioneering graphene nanoelectronic heterodyne sensor. The dipole detection mechanism is confirmed by a plethora of expts. with vapor mols. of various dipole moments, particularly, with cis- and trans-isomers that have different polarities. Rapid (down to ∼\n0.1 s) and sensitive (down to ∼\n1 ppb) detection of a wide range of vapor analytes is achieved, representing orders of magnitude improvement over state-of-the-art nanoelectronics sensors.
- 112Xuan, W.; He, M.; Meng, N.; He, X.; Wang, W.; Chen, J.; Shi, T.; Hasan, T.; Xu, Z.; Xu, Y.; Luo, J. K. Fast Response and High Sensitivity ZnO/Glass Surface Acoustic Wave Humidity Sensors Using Graphene Oxide Sensing Layer Sci. Rep. 2014, 4, 7206 DOI: 10.1038/srep07206Google Scholar112https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2MXhtFOjurzL&md5=01bb02cfdb39d681ab9282959c39c594Fast Response and High Sensitivity ZnO/glass Surface Acoustic Wave Humidity Sensors Using Graphene Oxide Sensing LayerXuan, Weipeng; He, Mei; Meng, Nan; He, Xingli; Wang, Wenbo; Chen, Jinkai; Shi, Tianjin; Hasan, Tawfique; Xu, Zhen; Xu, Yang; Luo, J. K.Scientific Reports (2014), 4 (), 7206CODEN: SRCEC3; ISSN:2045-2322. (Nature Publishing Group)We report ZnO/glass surface acoustic wave (SAW) humidity sensors with high sensitivity and fast response using graphene oxide sensing layer. The frequency shift of the sensors is exponentially correlated to the humidity change, induced mainly by mass loading effect rather than the complex impedance change of the sensing layer. The SAW sensors show high sensitivity at a broad humidity range from 0.5%RH to 85%RH with < 1 s rise time. The simple design and excellent stability of our GO-based SAW humidity sensors, complemented with full humidity range measurement, highlights their potential in a wide range of applications.
- 113Mogera, U.; Sagade, A. A.; George, S. J.; Kulkarni, G. U. Ultrafast Response Humidity Sensor Using Supramolecular Nanofibre and Its Application in Monitoring Breath Humidity and Flow Sci. Rep. 2014, 4, 4103 DOI: 10.1038/srep04103Google Scholar113https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2cXmvVKmsLg%253D&md5=d917a5a987a2dc642d70ad4433941386Ultrafast response humidity sensor using supramolecular nanofibre and its application in monitoring breath humidity and flowMogera, Umesha; Sagade, Abhay A.; George, Subi J.; Kulkarni, Giridhar U.Scientific Reports (2014), 4 (), 4103CODEN: SRCEC3; ISSN:2045-2322. (Nature Publishing Group)Measuring humidity in dynamic situations calls for highly sensitive fast response sensors. Here we report, a humidity sensor fabricated using soln. processed supramol. nanofibres as active resistive sensing material. The nanofibres are built via self- assembly of donor and acceptor mols. (coronene tetracarboxylate and dodecyl Me viologen resp.) involved in charge transfer interactions. The cond. of the nanofibre varied sensitively over a wide range of relative humidity (RH) with unprecedented fast response and recovery times. Based on UV-vis, XRD and AFM measurements, it is found that the stacking distance in the nanofibre decreases slightly while the charge transfer band intensity increases, all observations implying enhanced charge transfer interaction and hence the cond. It is demonstrated to be as a novel breath sensor which can monitor the respiration rate. Using two humidity sensors, a breath flow sensor was made which could simultaneously measure RH and flow rate of exhaled nasal breath. The integrated device was used for monitoring RH in the exhaled breath from volunteers undergoing exercise and alc. induced dehydration.
- 114Fu, K.; Chen, S.; Zhao, J.; Willis, B. G. Dielectrophoretic Assembly of Gold Nanoparticles in Nanoscale Junctions for Rapid, Miniature Chemiresistor Vapor Sensors ACS Sens. 2016, 1, 444– 450 DOI: 10.1021/acssensors.6b00041Google Scholar114https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC28Xjs1Ors7o%253D&md5=4f134867561b373bd5a08908bbb4a52aDielectrophoretic Assembly of Gold Nanoparticles in Nanoscale Junctions for Rapid, Miniature Chemiresistor Vapor SensorsFu, Kan; Chen, Shutang; Zhao, Jing; Willis, Brian G.ACS Sensors (2016), 1 (4), 444-450CODEN: ASCEFJ; ISSN:2379-3694. (American Chemical Society)A method for fabricating integrated arrays of nanoscale chemiresistor vapor sensors using functionalized gold nanoparticles is presented. Controlled placement of nanoparticles was accomplished with dielectrophoresis, achieving localized nanoparticle assembly between 50-nm-thick, 100-nm-wide nanofabricated electrodes with 50 nm spacing. Each individual sensor comprises an assembly of thiol-functionalized 10-nm-diam. gold nanoparticles, making a total active sensing vol. with thickness of 30 to 40 nm and area dimension 50 nm × 50 nm. The small electrode spacing enables contiguous films of just 3 to 4 layers of nanoparticles. Combination of top-down lithog. fabrication and bottom-up directed assembly allows multiple sensors spaced by 200 μm to be fabricated on a single chip. A second set of chemiresistor sensors with larger 20 μm electrode spacing and 200-300 nm film thickness were fabricated for comparison. Nanoscale sensors fabricated using 4 different types of thiolated capping ligands exhibited response sensitivity and selectivity similar to the larger chemiresistor sensors, but with a signal-to-noise degrdn. to 25% of the micron scale devices. The results demonstrate that nanofabricated sensors with dense arrays of many different types of functionalized nanoparticles can be integrated on a single chip, and it should be possible to create integrated, independent nanoscale sensors sepd. by only hundreds of nanometers.
- 115Zhou, Y.; Freitag, M.; Hone, J.; Staii, C.; Johnson, A. T.; Pinto, N. J.; MacDiarmid, A. G. Fabrication and Electrical Characterization of Polyaniline-Based Nanofibers with Diameter Below 30 nm Appl. Phys. Lett. 2003, 83, 3800– 3802 DOI: 10.1063/1.1622108Google ScholarThere is no corresponding record for this reference.
- 116Dong, C.; Li, Q.; Chen, G.; Xiao, X.; Wang, Y. Enhanced Formaldehyde Sensing Performance of 3D Hierarchical Porous Structure Pt-Functionalized NiO Via a Facile Solution Combustion Synthesis Sens. Actuators, B 2015, 220, 171– 179 DOI: 10.1016/j.snb.2015.05.056Google Scholar116https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2MXhtVaisL7J&md5=0423e204767a0b07bbd1105bcd38070bEnhanced formaldehyde sensing performance of 3D hierarchical porous structure Pt-functionalized NiO via a facile solution combustion synthesisDong, Chengjun; Li, Qing; Chen, Gang; Xiao, Xuechun; Wang, YudeSensors and Actuators, B: Chemical (2015), 220 (), 171-179CODEN: SABCEB; ISSN:0925-4005. (Elsevier B.V.)A facial soln. combustion synthesis is reported for prepg. pristine NiO and Pt-functionalized (0.5%, 1%, and 2% Pt loading) NiO. It was found that the obtained products exhibit 3D hierarchical porous structure regardless the Pt-loaded amts. due to the release of gases and the loosely packed NiO particles. Compared with the pristine NiO, the presence of Pt nanoparticles somehow affected the growth behavior of NiO around and embedded on these relatively big NiO nanoparticles in different size. The Pt-functionalized NiO based gas sensor showed lower operating temp. and substantially enhanced responses to formaldehyde, esp. 1% Pt-loaded NiO. The 1% Pt-loaded NiO based gas sensor displayed a response value of 9.90 to 2000 ppm formaldehyde at 200°C, whereas the pristine NiO based gas sensor only showed a response of 3.15 under the same conditions. The plausible explanation for the Pt-functionalized NiO based gas sensors to enhance the gas sensing performance is attributed to the role of Pt on the catalytic oxidn. of formaldehyde and the increase of oxygen species quantity.
- 117Maffei, F.; Betti, P.; Genovese, D.; Montalti, M.; Prodi, L.; De Zorzi, R.; Geremia, S.; Dalcanale, E. Highly Selective Chemical Vapor Sensing by Molecular Recognition: Specific Detection of C1-C4 Alcohols with a Fluorescent Phosphonate Cavitand Angew. Chem., Int. Ed. 2011, 50, 4654– 4657 DOI: 10.1002/anie.201100738Google ScholarThere is no corresponding record for this reference.
- 118Fu, K.; Willis, B. G. Characterization of DNA as a Solid-State Sorptive Vapor Sensing Material Sens. Actuators, B 2015, 220, 1023– 1032 DOI: 10.1016/j.snb.2015.05.132Google Scholar118https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2MXhtVOmtLrP&md5=032f864ac40cfde2ac8013f1a213c5b2Characterization of DNA as a solid-state sorptive vapor sensing materialFu, Kan; Willis, Brian G.Sensors and Actuators, B: Chemical (2015), 220 (), 1023-1032CODEN: SABCEB; ISSN:0925-4005. (Elsevier B.V.)Solid-state DNA was investigated for mass-based detection of common volatile org. compds. (VOCs) with a quartz crystal microbalance (QCM). Acoustically thin coatings of DNA films produced gravimetric vapor sorption responses with selectivity and response speeds comparable to conventional synthetic polymer coatings. Short-sequence single-strand DNA oligonucleotides exhibit amphiphilic sorption properties, responding to both polar and non-polar org. vapors. In the vapor concn. range p/p0 < 0.06, sensor response is linear. Sensors have selective responses that are dependent on oligomer compn., sequence length, and salting conditions. QCM-derived equil. consts. were analyzed by linear solvation energy relationships (LSER) for 20 vapors with a broad range of chem. properties, showing differences between DNA oligomers related to compn. Secondary structure effects were not discernable from the vapor sorption data, but LSER properties provide a ref. point for understanding DNA as a vapor sorption material.
- 119Sensor Specifications and Cross-Sensitivities; RAE Systems Technical Note TN-114; RAE Systems, Inc.: San Jose, CA, 2013; http://www.raesystems.com.br/sites/default/files/downloads/tn-114-sensor-specifications-and-cross-sensitivities.pdf (accessed July 27, 2016).Google ScholarThere is no corresponding record for this reference.
- 120Catalytic Combustible Gas Sensors; International Sensor Technology: Irvine, CA; http://www.intlsensor.com/pdf/catalyticbead.pdf (accessed July 27, 2016) .Google ScholarThere is no corresponding record for this reference.
- 121Yun, Y. J.; Hong, W. G.; Choi, N.-J.; Kim, B. H.; Jun, Y.; Lee, H.-K. Ultrasensitive and Highly Selective Graphene-Based Single Yarn for Use in Wearable Gas Sensor Sci. Rep. 2015, 5, 10904 DOI: 10.1038/srep10904Google Scholar121https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2MXhtFOrsbfF&md5=48f39f529bcb22eb9d2f4e0b9949cc32Ultrasensitive and Highly Selective Graphene-Based Single Yarn for Use in Wearable Gas SensorYun, Yong Ju; Hong, Won G.; Choi, Nak-Jin; Kim, Byung Hoon; Jun, Yongseok; Lee, Hyung-KunScientific Reports (2015), 5 (), 10904CODEN: SRCEC3; ISSN:2045-2322. (Nature Publishing Group)Elec. components based on fibers or textiles have been investigated owing to their potential applications in wearable devices. High performance on response to gas, drape-ability and washing durability are of important for gas sensors based on fiber substrates. In this report, we demonstrate the bendable and washable electronic textile (e-textile) gas sensors composed of reduced graphene oxides (RGOs) using com. available yarn and mol. glue through an electrostatic self-assembly. The e-textile gas sensor possesses chem. durability to several detergent washing treatments and mech. stability under 1,000 bending tests at an extreme bending radius of 1 mm as well as a high response to NO2 gas at room temp. with selectivity to other gases such as acetone, ethanol, ethylene, and CO2.
- 122Qin, X.; Wang, R.; Tsow, F.; Forzani, E.; Xian, X.; Tao, N. A Colorimetric Chemical Sensing Platform for Real-Time Monitoring of Indoor Formaldehyde IEEE Sens. J. 2015, 15, 1545– 1551 DOI: 10.1109/JSEN.2014.2364142Google Scholar122https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2MXltVeitLs%253D&md5=57619254c881452fda16d3773682a875A colorimetric chemical sensing platform for real-time monitoring of indoor formaldehydeQin, Xingcai; Wang, Rui; Tsow, Francis; Forzani, Erica; Xian, Xiaojun; Tao, NongjianIEEE Sensors Journal (2015), 15 (3), 1545-1551CODEN: ISJEAZ; ISSN:1530-437X. (Institute of Electrical and Electronics Engineers)Formaldehyde is one of the most important indoor air pollutants affecting human immune system, and causing various respiratory diseases and even certain cancers. Traditional formaldehyde detection technologies are bulky, expensive and difficult to maintain. Here, we report a colorimetric chem. sensing platform for fast (2 min) and sensitive detection (30 ppbv) of formaldehyde over a wide dynamic range (0-750 ppbv). The sensor can tolerate humidity variation from 5% to 90% and is immune of common interferents, such as CO2 (4%), SO2 (10 ppm), NO2 (125 ppbv), and O3 (300 ppbv) in air. We also demonstrated continuous detection of formaldehyde on this sensing platform using disposable sensor chip.
- 123Booksh, K. S.; Kowalski, B. R. Theory of Analytical Chemistry Anal. Chem. 1994, 66, 782A– 791A DOI: 10.1021/ac00087a718Google Scholar123https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADyaK2cXlt1Cju7s%253D&md5=55d1a6ad9831b8fe6e957c27430f1ea2Theory of analytical chemistryBooksh, Karl S.; Kowalski, Bruce R.Analytical Chemistry (1994), 66 (15), 782A-791ACODEN: ANCHAM; ISSN:0003-2700.The title topic is reviewed and discussed. A guiding theory of anal. chem. can be used to specify what information can be extd. from the data produced by an anal. instrument or method.
- 124Eranna, G.; Joshi, B. C.; Runthala, D. P.; Gupta, R. P. Oxide Materials for Development of Integrated Gas Sensors - a Comprehensive Review Crit. Rev. Solid State Mater. Sci. 2004, 29, 111– 188 DOI: 10.1080/10408430490888977Google Scholar124https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD2cXhtFGgu77O&md5=95d5e64329dc8bf0b28c5a403c5b0879Oxide materials for development of integrated gas sensors. A comprehensive reviewEranna, G.; Joshi, B.; Runthala, D.; Gupta, R.Critical Reviews in Solid State and Materials Sciences (2004), 29 (3-4), 111-188CODEN: CCRSDA; ISSN:1040-8436. (Taylor & Francis, Inc.)A review. In the recent past a great deal of research efforts were directed toward the development of miniaturized gas-sensing devices, particularly for toxic gas detection and for pollution monitoring. Though various techniques are available for gas detection, solid state metal oxides offer a wide spectrum of materials and their sensitivities for different gaseous species, making it a better choice over other options. In this article a crit. parameter anal. of different metal oxides that are known to be sensitive to various gaseous species are thoroughly examd. This includes phase of the oxide, sensing gaseous species, operating temp. range, and phys. form of the material for the development of integrated gas sensors. The oxides that are covered in this study include oxides of aluminum, bismuth, cadmium, cerium, chromium, cobalt, copper, gallium, indium, iron, manganese, molybdenum, nickel, niobium, ruthenium, tantalum, tin, titanium, tungsten, vanadium, zinc, zirconium, and the mixed or multi-component metal oxides. They cover gases such as CO, CO2, CH4, C2H5OH, C3H8, H2, H2S, NH3, NO, NO2, O2, O3, SO2, acetone, dimethylamine (DMA), humidity, liq. petroleum gas (LPG), petrol, trimethylamine (TMA), smoke, and many others. Both doped and undoped oxides were analyzed for the compatibility with silicon processing conditions and hybrid microcircuit fabrication techniques. In silicon processing conditions, they are further analyzed for the suitability for simple silicon surfaces, silicon-on-insulator (SOI) surfaces, and micromachined silicon geometries for different operating temps. Discussion on gas-sensing properties of each material and its applications are described in the text in alphabetical order of the elemental oxides. Further, the gas-sensing properties like sensitivity, detection limits, operating temp., and so on are summarized in tables along with relevant refs. The figures incorporated in the present review are primarily based on discussions and data in tables. However, these figures provide a qual. comparison and present a pictorial view to examine suitability of a material for a particular application. From the known parameters, the present study clearly indicates the suitability of certain materials and the gases that they cover for the development of integrated micro-gas sensors. A clear picture was brought out for the development of silicon-based processing technol. Various parameters are discussed for the selection of these materials, to examine their suitability and practical problems that are being assocd. Etching of these metal oxides and the reliability of devices are also discussed.
- 125Chen, X.; Wong, C. K. Y.; Yuan, C. A.; Zhang, G. Nanowire-Based Gas Sensors Sens. Actuators, B 2013, 177, 178– 195 DOI: 10.1016/j.snb.2012.10.134Google Scholar125https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC3sXhsFKnurg%253D&md5=11b697cbdcf28c28a6b1a1f80d1a7d56Nanowire-based gas sensorsChen, Xianping; Wong, Cell K. Y.; Yuan, Cadmus A.; Zhang, GuoqiSensors and Actuators, B: Chemical (2013), 177 (), 178-195CODEN: SABCEB; ISSN:0925-4005. (Elsevier B.V.)A review. Gas sensors fabricated with nanowires as the detecting elements are powerful due to their many improved characteristics such as high surface-to-vol. ratios, ultrasensitivity, higher selectivity, low power consumption, and fast response. This paper gives an overview on the recent process of the development of nanotechnol. and nanowire-based gas sensors. The two basic approaches, top-down and bottom-up, for prepn. of nanowires are compared. The conduction mechanisms, sensing performances, configurations, and sensing principles of different nanowire gas sensors and arrays are summarized and discussed. Meanwhile, an emerging nanowires fabrication method and a self-powered nanowire pH sensor are highlighted. The scientific and technol. challenges in the field are discussed at the end of the review.
- 126Llobet, E. Gas Sensors Using Carbon Nanomaterials: A Review Sens. Actuators, B 2013, 179, 32– 45 DOI: 10.1016/j.snb.2012.11.014Google Scholar126https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC38XhvVakur%252FE&md5=bb2a0d1928a37d1d084f9cfeb269d6baGas sensors using carbon nanomaterials: A reviewLlobet, EduardSensors and Actuators, B: Chemical (2013), 179 (), 32-45CODEN: SABCEB; ISSN:0925-4005. (Elsevier B.V.)A review. Carbon nanomaterials were attracting a great deal of research interest in the last few years. Their unique elec., optical and mech. properties make them very interesting for developing the new generation of miniaturized, low-power, ubiquitous sensors. In the particular case of gas sensing, some carbon nanomaterials such as nanofibers, nanotubes and graphene are threatening the dominance position of other well established (nano)materials, yet the com. exploitation of carbon nanomaterials is still a way off. This paper reviews the state of the art for elec. gas sensors employing carbon nanomaterials, identifies the bottlenecks that impair their commercialization and also some recent breakthroughs. Finally an outlook in which challenges and opportunities are identified is given.
- 127Liu, Y.; Parisi, J.; Sun, X.; Lei, Y. Solid-State Gas Sensors for High Temperature Applications - A Review J. Mater. Chem. A 2014, 2, 9919– 9943 DOI: 10.1039/c3ta15008aGoogle Scholar127https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2cXhtVWmu7vP&md5=9ac4dc057623aa038842d2fae6cfb9a4Solid-state gas sensors for high temperature applications - a reviewLiu, Yixin; Parisi, Joseph; Sun, Xiangcheng; Lei, YuJournal of Materials Chemistry A: Materials for Energy and Sustainability (2014), 2 (26), 9919-9943CODEN: JMCAET; ISSN:2050-7496. (Royal Society of Chemistry)A review covering a variety of solid-state gas sensors which operate at high temps. (>600°) for industrial applications, e.g., combustion processes, and are essential to improve energy efficiency and reduce toxic emissions, is given. Basic operating principles for each type of solid-state sensor are briefly presented. Key results and previous studies on high temp. O2, CO, hydrocarbon, and NOx sensors are discussed, emphasizing development of suitable electrolytes and sensing materials with good thermal stability and sensing performance for these high temp. gas sensing applications. Topics discussed include: solid-state gas sensing technologies (solid electrolyte-based gas sensors [equil. potentiometric gas sensors, non-equil. potentiometric {mixed potential} gas sensors, amperometric gas sensors], resistive gas sensors, impedancemetric gas sensors); recent progress in high temp. gas sensors (O2 sensors [equil. potentiometric {Type 1}], amperometric {limiting current}, resistor-type); combustible gas (CO and hydrocarbon) sensors (resistor-type, mixed potential); NOx sensors (amperometric, mixed potential, impedancemetric); challenges for solid-state gas sensors used in high temp. applications; and conclusions and future trends.
- 128Neri, G. First Fifty Years of Chemoresistive Gas Sensors Chemosensors 2015, 3, 1– 20 DOI: 10.3390/chemosensors3010001Google Scholar128https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2sXjt1Olsr8%253D&md5=93ad57b4d8439a818ccdce654c322ec3First fifty years of chemoresistive gas sensorsNeri, GiovanniChemosensors (2015), 3 (1), 1-20CODEN: CHEMQ9; ISSN:2227-9040. (MDPI AG)The first fifty years of chemoresistive sensors for gas detection are here reviewed, focusing on the main scientific and technol. innovations that have occurred in the field over the course of these years. A look at advances made in fundamental and applied research and leading to the development of actual high performance chemoresistive devices is presented. The approaches devoted to the synthesis of novel semiconducting materials with unprecedented nanostructure and gas-sensing properties have been also presented. Perspectives on new technologies and future applications of chemoresistive gas sensors have also been highlighted.
- 129Wales, D. J.; Grand, J.; Ting, V. P.; Burke, R. D.; Edler, K. J.; Bowen, C. R.; Mintova, S.; Burrows, A. D. Gas Sensing Using Porous Materials for Automotive Applications Chem. Soc. Rev. 2015, 44, 4290– 4321 DOI: 10.1039/C5CS00040HGoogle Scholar129https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2MXosFKltLY%253D&md5=ef9d247e7e3de378e9ff21e9221fb1b7Gas sensing using porous materials for automotive applicationsWales, Dominic J.; Grand, Julien; Ting, Valeska P.; Burke, Richard D.; Edler, Karen J.; Bowen, Chris R.; Mintova, Svetlana; Burrows, Andrew D.Chemical Society Reviews (2015), 44 (13), 4290-4321CODEN: CSRVBR; ISSN:0306-0012. (Royal Society of Chemistry)Improvements in the efficiency of combustion within a vehicle can lead to redns. in the emission of harmful pollutants and increased fuel efficiency. Gas sensors have a role to play in this process, since they can provide real time feedback to vehicular fuel and emissions management systems as well as reducing the discrepancy between emissions obsd. in factory tests and 'real world' scenarios. In this review we survey the current state-of-the-art in using porous materials for sensing the gases relevant to automotive emissions. Two broad classes of porous material - zeolites and metal-org. frameworks (MOFs) - are introduced, and their potential for gas sensing is discussed. The adsorptive, spectroscopic and electronic techniques for sensing gases using porous materials are summarised. Examples of the use of zeolites and MOFs in the sensing of water vapor, oxygen, NOx, carbon monoxide and carbon dioxide, hydrocarbons and volatile org. compds., ammonia, hydrogen sulfide, sulfur dioxide and hydrogen are then detailed. Both types of porous material (zeolites and MOFs) reveal great promise for the fabrication of sensors for exhaust gases and vapors due to high selectivity and sensitivity. The size and shape selectivity of the zeolite and MOF materials are controlled by variation of pore dimensions, chem. compn. (hydrophilicity/hydrophobicity), crystal size and orientation, thus enabling detection and differentiation between different gases and vapors.
- 130Zhou, X.; Lee, S.; Xu, Z.; Yoon, J. Recent Progress on the Development of Chemosensors for Gases Chem. Rev. 2015, 115, 7944– 8000 DOI: 10.1021/cr500567rGoogle Scholar130https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2MXit1Shu7g%253D&md5=834a8b4fbee6ab3bae613fbaf9df4ed5Recent Progress on the Development of Chemosensors for GasesZhou, Xin; Lee, Songyi; Xu, Zhaochao; Yoon, JuyoungChemical Reviews (Washington, DC, United States) (2015), 115 (15), 7944-8000CODEN: CHREAY; ISSN:0009-2665. (American Chemical Society)In this review, we attempt to describe investigations of gas chemosensors carried out in recent decades in a systematic and inclusive manner. The coverage of this topic is divided into three sections according to the different types of chemosensors, including those that are based on newly designed fluorescent org. mols., semiconducting oxides, as well as nanomaterials. In each section, discussion is organized to cover the different characteristics and/or sources of the gases, exemplified by those involved in environmental exhausts (CO2,SO2, NOx, VOCs), biol. signaling (H2S, NO, 1O2), and toxic uses(nerve gases, sulfur mustard). In addn., design strategies,sensing mechanisms and performances, and related applicationsof chemosensors are also discussed in detail. The goal of the current review is to present comprehensive coverage of recent progress that has been made in studies targeted at the designand development of chemosensors for gases and, by doing so, to stimulate future research studies in this rapidly expanding multidisciplinary area.
- 131Persaud, K.; Dodd, G. Analysis of Discrimination Mechanisms in the Mammalian Olfactory System Using a Model Nose Nature 1982, 299, 352– 355 DOI: 10.1038/299352a0Google Scholar131https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A280%3ADyaL383nt1Ciuw%253D%253D&md5=10c58203254f9c41a58043e470cc6d21Analysis of discrimination mechanisms in the mammalian olfactory system using a model nosePersaud K; Dodd GNature (1982), 299 (5881), 352-5 ISSN:0028-0836.Olfaction exhibits both high sensitivity for odours and high discrimination between them. We suggest that to make fine discriminations between complex odorant mixtures containing varying ratios of odorants without the necessity for highly specialized peripheral receptors, the olfactory systems makes use of feature detection using broadly tuned receptor cells organized in a convergent neurone pathway. As a test of this hypothesis we have constructed an electronic nose using semiconductor transducers and incorporating design features suggested by our proposal. We report here that this device can reproducibly discriminate between a wide variety of odours, and its properties show that discrimination in an olfactory system could be achieved without the use of highly specific receptors.
- 132Iwanaga, S.; Sato, N.; Ikegami, A.; Isogai, T.; Noro, T.; Arima, H. Gas Detection Device and Method for Detecting Gas. U.S. Patent 4,457,161, 1984.Google ScholarThere is no corresponding record for this reference.
- 133Zaromb, S.; Stetter, J. R. Theoretical Basis for Identification and Measurement of Air Contaminants Using an Array of Sensors Having Partly Overlapping Selectivities Sens. Actuators 1984, 6, 225– 243 DOI: 10.1016/0250-6874(84)85019-2Google Scholar133https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADyaL2MXksVWlu7c%253D&md5=a80fc4695728e00ca6ce8018c9430d85Theoretical basis for identification and measurement of air contaminants using an array of sensors having partly overlapping selectivitiesZaromb, S.; Stetter, J. R.Sensors and Actuators (1984), 6 (4), 225-43CODEN: SEACDX; ISSN:0250-6874.A theor. basis for the selection and effective use of an array of chem. sensors for a particular application is provided. The array is to be used in conjunction with a microprocessor in a small portable device capable of detecting, identifying and quantifying a large no. of hazardous compds., either individually or in mixts. A compact array of S different sensors is used, each of which can operate in M differently selective modes to yield P = MS parameters, or data channels. An inequality to det. the min. no. of parameters required to identify the compds. solely on the basis of the presence or absence of significant signals in the various channels is given. A computational approach is proposed to 1st eliminate all candidate compds. whose known response patterns do not overlap the channels exhibiting the strongest signals. The remaining candidate compds. are then quantified by solving simultaneous linear equations. A determinant, which is used to solve the simultaneous equations, provides a measure of the selectivity and/or nonredundancy of the set of channels exhibiting the strongest signals. This determinant is also inversely proportional to the exptl. error or to the required accuracy of the measurements. By computing the values of this determinant for various mixts., the selectivities and/or nonredundancies of alternative sets of P parameters with respect to a given set of N hazardous compds. can be evaluated and compared.
- 134Ikegami, A.; Kaneyasu, M. Olfactory Detection Using Integrated Sensor Proc. Transducers 85 1985, 136– 139Google ScholarThere is no corresponding record for this reference.
- 135Lim, S. H.; Feng, L.; Kemling, J. W.; Musto, C. J.; Suslick, K. S. An Optoelectronic Nose for the Detection of Toxic Gases Nat. Chem. 2009, 1, 562– 567 DOI: 10.1038/nchem.360Google Scholar135https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD1MXhtFKnsr3L&md5=e402ec6158371683fab436a90bd8760aAn optoelectronic nose for the detection of toxic gasesLim, Sung H.; Feng, Liang; Kemling, Jonathan W.; Musto, Christopher J.; Suslick, Kenneth S.Nature Chemistry (2009), 1 (7), 562-567CODEN: NCAHBB; ISSN:1755-4330. (Nature Publishing Group)The authors have developed a simple colorimetric sensor array that detects a wide range of volatile analytes and then applied it to the detection of toxic gases. The sensor consists of a disposable array of cross-responsive nanoporous pigments with colors that are changed by diverse chem. interactions with analytes. Although no single chem. responsive pigment is specific for any one analyte, the pattern of color change for the array is a unique mol. fingerprint. Clear differentiation among 19 different toxic industrial chems. (TICs) within two minutes of exposure at concns. immediately dangerous to life or health were demonstrated. Based on the color change of the array, quantification of each analyte was accomplished easily, and excellent detection limits were achieved, generally below the permissible exposure limits. Different TICs were identified readily using a std. chemometric approach (hierarchical clustering anal.), with no misclassifications over 140 trials.
- 136Peng, G.; Tisch, U.; Adams, O.; Hakim, M.; Shehada, N.; Broza, Y. Y.; Billan, S.; Abdah-Bortnyak, R.; Kuten, A.; Haick, H. Diagnosing Lung Cancer in Exhaled Breath Using Gold Nanoparticles Nat. Nanotechnol. 2009, 4, 669– 673 DOI: 10.1038/nnano.2009.235Google Scholar136https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD1MXht1aqsLvM&md5=42347bdae7135d869c87bd6bbc54fa1cDiagnosing lung cancer in exhaled breath using gold nanoparticlesPeng, Gang; Tisch, Ulrike; Adams, Orna; Hakim, Meggie; Shehada, Nisrean; Broza, Yoav Y.; Billan, Salem; Abdah-Bortnyak, Roxolyana; Kuten, Abraham; Haick, HossamNature Nanotechnology (2009), 4 (10), 669-673CODEN: NNAABX; ISSN:1748-3387. (Nature Publishing Group)Conventional diagnostic methods for lung cancer are unsuitable for widespread screening because they are expensive and occasionally miss tumors. Gas chromatog./mass spectrometry studies have shown that several volatile org. compds., which normally appear at levels of 1-20 ppb in healthy human breath, are elevated to levels between 10 and 100 ppb in lung cancer patients. Here we show that an array of sensors based on gold nanoparticles can rapidly distinguish the breath of lung cancer patients from the breath of healthy individuals in an atm. of high humidity. In combination with solid-phase microextn., gas chromatog./mass spectrometry was used to identify 42 volatile org. compds. that represent lung cancer biomarkers. Four of these were used to train and optimize the sensors, demonstrating good agreement between patient and simulated breath samples. Our results show that sensors based on gold nanoparticles could form the basis of an inexpensive and non-invasive diagnostic tool for lung cancer.
- 137Lichtenstein, A.; Havivi, E.; Shacham, R.; Hahamy, E.; Leibovich, R.; Pevzner, A.; Krivitsky, V.; Davivi, G.; Presman, I.; Elnathan, R.; Engel, Y.; Flaxer, E.; Patolsky, F. Supersensitive Fingerprinting of Explosives by Chemically Modified Nanosensors Arrays Nat. Commun. 2014, 5, 4195 DOI: 10.1038/ncomms5195Google Scholar137https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2cXitVShs7rE&md5=1e79975d3b5e9207dac4c8f305f9515cSupersensitive fingerprinting of explosives by chemically modified nanosensors arraysLichtenstein, Amir; Havivi, Ehud; Shacham, Ronen; Hahamy, Ehud; Leibovich, Ronit; Pevzner, Alexander; Krivitsky, Vadim; Davivi, Guy; Presman, Igor; Elnathan, Roey; Engel, Yoni; Flaxer, Eli; Patolsky, FernandoNature Communications (2014), 5 (), 4195CODEN: NCAOBW; ISSN:2041-1723. (Nature Publishing Group)The capability to detect traces of explosives sensitively, selectively and rapidly could be of great benefit for applications relating to civilian national security and military needs. Here, we show that, when chem. modified in a multiplexed mode, nanoelec. devices arrays enable the supersensitive discriminative detection of explosive species. The fingerprinting of explosives is achieved by pattern recognizing the inherent kinetics, and thermodn., of interaction between the chem. modified nanosensors array and the mol. analytes under test. This platform allows for the rapid detection of explosives, from air collected samples, down to the parts-per-quadrillion concn. range, and represents the first nanotechnol.-inspired demonstration on the selective supersensitive detection of explosives, including the nitro- and peroxide-derivs., on a single electronic platform. Furthermore, the ultrahigh sensitivity displayed by our platform may allow the remote detection of various explosives, a task unachieved by existing detection technologies.
- 138Beccherelli, R.; Zampetti, E.; Pantalei, S.; Bernabei, M.; Persaud, K. C. Design of a Very Large Chemical Sensor System for Mimicking Biological Olfaction Sens. Actuators, B 2010, 146, 446– 452 DOI: 10.1016/j.snb.2009.11.031Google Scholar138https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC3cXltFCqurY%253D&md5=05453c91b1edf6ea89de42eaf196b24dDesign of a very large chemical sensor system for mimicking biological olfactionBeccherelli, R.; Zampetti, E.; Pantalei, S.; Bernabei, M.; Persaud, K. C.Sensors and Actuators, B: Chemical (2010), 146 (2), 446-452CODEN: SABCEB; ISSN:0925-4005. (Elsevier B.V.)Olfactory receptor neurons in the mammalian olfactory system transduce the odor information into elec. signals and project these into the olfactory bulb. In the biol. system the huge redundancy and the massive convergence of the olfactory receptor neurons to the olfactory bulb are thought to enhance the sensitivity and selectivity of the system. To explore this concept a polymeric chem. sensor array consisting of 216 (65,536) sensors comprising tens of different types will be built in the frame of the FP7 NEUROCHEM project. To interface such a large sensor array, a topol. array configuration with n rows and m columns has been adopted in order to reduce the total wiring connections to n + m. A detailed numerical anal. of the elec. crosstalk deriving from such a configuration has been carried out for elucidating advantages and limitations of the scanning algorithm. A prototype of the transducing array has been designed and an electronic scanning system capable of reading the 65,536 sensing elements array has been realized.
- 139Bernabei, M.; Persaud, K. C.; Pantalei, S.; Zampetti, E.; Beccherelli, R. Large-Scale Chemical Sensor Array Testing Biological Olfaction Concepts IEEE Sens. J. 2012, 12, 3174– 3183 DOI: 10.1109/JSEN.2012.2207887Google ScholarThere is no corresponding record for this reference.
- 140Marco, S.; Gutiérrez-Gálvez, A.; Lansner, A.; Martinez, D.; Rospars, J. P.; Beccherelli, R.; Perera, A.; Pearce, T. C.; Verschure, P. F. M. J.; Persaud, K. A Biomimetic Approach to Machine Olfaction, Featuring a Very Large-Scale Chemical Sensor Array and Embedded Neuro-Bio-Inspired Computation Microsyst. Technol. 2014, 20, 729– 742 DOI: 10.1007/s00542-013-2020-8Google Scholar140https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC3sXhvFyksrnF&md5=1ba9fa52eda0962d496d2385d06e8b62A biomimetic approach to machine olfaction, featuring a very large-scale chemical sensor array and embedded neuro-bio-inspired computationMarco, S.; Gutierrez-Galvez, A.; Lansner, A.; Martinez, D.; Rospars, J. P.; Beccherelli, R.; Perera, A.; Pearce, T. C.; Verschure, P. F. M. J.; Persaud, K.Microsystem Technologies (2014), 20 (4-5), 729-742CODEN: MCTCEF; ISSN:0946-7076. (Springer)A review. Biol. olfaction outperforms chem. instrumentation in specificity, response time, detection limit, coding capacity, time stability, robustness, size, power consumption, and portability. This biol. function provides outstanding performance due, in a large extent, to the unique architecture of the olfactory pathway, which combines a high degree of redundancy and efficient combinatorial coding, with unmatched chem. information processing mechanisms. The last decade has seen important advances in the understanding of the computational primitives underlying the functioning of the olfactory system. The EU-funded Project NEUROCHEM (Bio-ICT-FET- 216916) developed novel computing paradigms and biol. motivated artifacts for chem. sensing, taking its inspiration from the biol. olfactory pathway. To demonstrate this approach, a biomimetic demonstrator has been built that features a very large-scale sensor array (65,536 elements) using conducting polymer technol. which mimics the olfactory receptor neuron layer. It implements derived computational neuroscience algorithms in an embedded system that interfaces the chem. sensors and processes their signals in real-time. This embedded system integrates abstracted computational models of the main anat. building blocks in the olfactory pathway: the olfactory bulb, and olfactory cortex in vertebrates (resp., antennal lobe and mushroom bodies in the insect). For implementation in the embedded processor, an abstraction phase has been carried out in which their processing capabilities are captured by algorithmic solns. implemented in software. Finally, the algorithmic models are tested in mixed chem. plumes with an odor robot having navigation capabilities.
- 141Shurmer, H. V. Basic Limitations for an Electronic Nose Sens. Actuators, B 1990, 1, 48– 53 DOI: 10.1016/0925-4005(90)80170-5Google ScholarThere is no corresponding record for this reference.
- 142Bourgeois, W.; Romain, A.-C.; Nicolas, J.; Stuetz, R. M. The Use of Sensor Arrays for Environmental Monitoring: Interests and Limitations J. Environ. Monit. 2003, 5, 852– 860 DOI: 10.1039/b307905hGoogle Scholar142https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD3sXpt1GmtL0%253D&md5=a7d506696a6ff72b930b0d85c3ac98b3The use of sensor arrays for environmental monitoring: interests and limitationsBourgeois, Wilfrid; Romain, Anne-Claude; Nicolas, Jacques; Stuetz, Richard M.Journal of Environmental Monitoring (2003), 5 (6), 852-860CODEN: JEMOFW; ISSN:1464-0325. (Royal Society of Chemistry)A review. Continuous, in situ monitoring of air, water and land quality is fundamental to most environmental applications. Low cost and non-invasive chem. sensor arrays provide a suitable technique for in situ monitoring. Their ability and performance under realistic conditions is discussed. Published studies report promising results despite a no. of limitations that are assocd. with both the technol. itself and its application in ever changing ambient conditions. Early studies include the anal. of single substances as well as odor and wastewater org. load monitoring. Reported applications typically highlight the sensitivity of the currently available sensors to changes in temp., humidity and flow rate. Two types of approaches are recommended to deal with these effects: either working under fixed exptl. conditions or measuring the external parameters to numerically compensate for their change. The main challenge assocd. using nonspecific sensor arrays lies in establishing a relation between the measured multivariate signals and the stds. metrics that are traditionally used for quality assessment of gas mixts. For instance, odor monitoring requires calibration against olfactometric measurements while studies of wastewater samples still need to be correlated with org. pollution parameters such as BOD, COD or TOC. However, results obtained in the field demonstrated how sensor arrays can be readily used as simple alarm devices or as early warning systems based on a general air/water quality index.
- 143Röck, F.; Barsan, N.; Weimar, U. Electronic Nose: Current Status and Future Trends Chem. Rev. 2008, 108, 705– 725 DOI: 10.1021/cr068121qGoogle Scholar143https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A280%3ADC%252BD1c7htFKquw%253D%253D&md5=1d98c868477a71e49cad42752f190bdeElectronic nose: current status and future trendsRock Frank; Barsan Nicolae; Weimar UdoChemical reviews (2008), 108 (2), 705-25 ISSN:0009-2665.There is no expanded citation for this reference.
- 144Gutierrez-Osuna, R.; Hierlemann, A. Adaptive Microsensor Systems Annu. Rev. Anal. Chem. 2010, 3, 255– 276 DOI: 10.1146/annurev.anchem.111808.073620Google Scholar144https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC3cXhtVOlsrzL&md5=4c0229b080e6084de1a80bfecd01b240Adaptive microsensor systemsGutierrez-Osuna, Ricardo; Hierlemann, AndreasAnnual Review of Analytical Chemistry (2010), 3 (), 255-276CODEN: ARACFU; ISSN:1936-1327. (Annual Reviews Inc.)A review. The authors provide a broad review of approaches for developing chemosensor systems whose operating parameters can adapt in response to environmental changes or application needs. Adaptation may take place at the instrumentation level (e.g., tunable sensors) and at the data-anal. level (e.g., adaptive classifiers). Several strategies that provide tunability at the device level: modulation of internal sensing parameters, such as frequencies and operation voltages; variation of external parameters, such as exposure times and catalysts; and development of compact microanal. systems with multiple tuning options are discussed. At the data-anal. level, adaptive filters for change, interference, and drift rejection; pattern classifiers that can adapt to changes in the statistical properties of training data; and active-sensing techniques that can tune sensing parameters in real time are considered. The authors conclude with a discussion of future opportunities for adaptive sensing in wireless distributed sensor systems.
- 145Stitzel, S. E.; Aernecke, M. J.; Walt, D. R. Artificial Noses Annu. Rev. Biomed. Eng. 2011, 13, 1– 25 DOI: 10.1146/annurev-bioeng-071910-124633Google Scholar145https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC3MXhtFCit7zI&md5=35342e14e9bd12fd19a73f604809496cArtificial nosesStitzel, Shannon E.; Aernecke, Matthew J.; Walt, David R.Annual Review of Biomedical Engineering (2011), 13 (), 1-25CODEN: ARBEF7; ISSN:1523-9829. (Annual Reviews Inc.)A review. The mammalian olfactory system is able to detect many more odorants than the no. of receptors it has by utilizing cross-reactive odorant receptors that generate unique response patterns for each odorant. Mimicking the mammalian system, artificial noses combine cross-reactive sensor arrays with pattern recognition algorithms to create robust odor-discrimination systems. The first artificial nose reported in 1982 utilized a tin-oxide sensor array. Since then, however, a wide range of sensor technologies have been developed and commercialized. This review highlights the most commonly employed sensor types in artificial noses: elec., gravimetric, and optical sensors. The applications of nose systems are also reviewed, covering areas such as food and beverage quality control, chem. warfare agent detection, and medical diagnostics. A brief discussion of future trends for the technol. is also provided.
- 146Marco, S.; Gutierrez-Galvez, A. Signal and Data Processing for Machine Olfaction and Chemical Sensing: A Review IEEE Sens. J. 2012, 12, 3189– 3214 DOI: 10.1109/JSEN.2012.2192920Google ScholarThere is no corresponding record for this reference.
- 147Askim, J. R.; Mahmoudi, M.; Suslick, K. S. Optical Sensor Arrays for Chemical Sensing: The Optoelectronic Nose Chem. Soc. Rev. 2013, 42, 8649– 8682 DOI: 10.1039/c3cs60179jGoogle Scholar147https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC3sXhs1CmurjE&md5=86c1fb67dad1e05b60445c96170abc6aOptical sensor arrays for chemical sensing: the optoelectronic noseAskim, Jon R.; Mahmoudi, Morteza; Suslick, Kenneth S.Chemical Society Reviews (2013), 42 (22), 8649-8682CODEN: CSRVBR; ISSN:0306-0012. (Royal Society of Chemistry)A comprehensive review is presented on the development and state of the art of colorimetric and fluorometric sensor arrays. Optical arrays based on chemoresponsive colorants (dyes and nanoporous pigments) probe the chem. reactivity of analytes, rather than their phys. properties. This provides a high dimensionality to chem. sensing that permits high sensitivity (often down to ppb levels), impressive discrimination among very similar analytes and exquisite fingerprinting of extremely similar mixts. over a wide range of analyte types, both in the gas and liq. phases.
- 148Chiu, S. W.; Tang, K. T. Towards a Chemiresistive Sensor-Integrated Electronic Nose: A Review Sensors 2013, 13, 14214– 14247 DOI: 10.3390/s131014214Google Scholar148https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2cXlsVWnsLY%253D&md5=ff7b1fdfa83dcaaa2ce98c936e286e00Towards a chemiresistive sensor-integrated electronic nose: A reviewChiu, Shih-Wen; Tang, Kea-TiongSensors (2013), 13 (10), 14214-14247CODEN: SENSC9; ISSN:1424-8220. (MDPI AG)Electronic noses have potential applications in daily life, but are restricted by their bulky size and high price. This review focuses on the use of chemiresistive gas sensors, metal-oxide semiconductor gas sensors and conductive polymer gas sensors in an electronic nose for system integration to reduce size and cost. The review covers the system design considerations and the complementary metal-oxide-semiconductor integrated technol. for a chemiresistive gas sensor electronic nose, including the integrated sensor array, its readout interface, and pattern recognition hardware. In addn., the state-of-the-art technol. integrated in the electronic nose is also presented, such as the sensing front-end chip, electronic nose signal processing chip, and the electronic nose system-on-chip.
- 149Peris, M.; Escuder-Gilabert, L. On-Line Monitoring of Food Fermentation Processes Using Electronic Noses and Electronic Tongues: A Review Anal. Chim. Acta 2013, 804, 29– 36 DOI: 10.1016/j.aca.2013.09.048Google Scholar149https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC3sXhs1Wit77F&md5=2bf3d2a2ca9c0da147bf4617563cbc1aOn-line monitoring of food fermentation processes using electronic noses and electronic tongues: A reviewPeris, Miguel; Escuder-Gilabert, LauraAnalytica Chimica Acta (2013), 804 (), 29-36CODEN: ACACAM; ISSN:0003-2670. (Elsevier B.V.)A review. Fermn. processes are often sensitive to even slight changes of conditions that may result in unacceptable end-product quality. Thus, close follow-up of this type of processes is crit. for detecting unfavorable deviations as early as possible in order to save downtime, materials and resources. Nevertheless the use of traditional anal. techniques is often hindered by the need for expensive instrumentation and experienced operators and complex sample prepn. In this sense, one of the most promising ways of developing rapid and relatively inexpensive methods for quality control in fermn. processes is the use of chem. multisensor systems. In this work we present an overview of the most important contributions dealing with the monitoring of fermn. processes using electronic noses and electronic tongues. After a brief description of the fundamentals of both types of devices, the different approaches are critically commented, their strengths and weaknesses being highlighted. Finally, future trends in this field are also mentioned in the last section of the article.
- 150García-Muñoz, R. A.; Morales, V.; Toledano, A. Cancer Diagnosis by Breath Analysis: What Is the Future? Bioanalysis 2014, 6, 2331– 2333 DOI: 10.4155/bio.14.180Google ScholarThere is no corresponding record for this reference.
- 151Gutiérrez, J.; Horrillo, M. C. Advances in Artificial Olfaction: Sensors and Applications Talanta 2014, 124, 95– 105 DOI: 10.1016/j.talanta.2014.02.016Google Scholar151https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2cXmvVWqtrk%253D&md5=b41b50aeb51c7bf49cadda92ce3ee4bcAdvances in artificial olfaction: Sensors and applicationsGutierrez, J.; Horrillo, M. C.Talanta (2014), 124 (), 95-105CODEN: TLNTA2; ISSN:0039-9140. (Elsevier B.V.)A review. The artificial olfaction, based on electronic systems (electronic noses), includes three basic functions that operate on an odorant: a sample handler, an array of gas sensors, and a signal-processing method. The response of these artificial systems can be the identity of the odorant, an est. concn. of the odorant, or characteristic properties of the odor as might be perceived by a human. These electronic noses are bio inspired instruments that mimic the sense of smell. The complexity of most odorants makes characterization difficult with conventional anal. techniques, such as gas chromatog. Sensory anal. by a panel of experts is a costly process since it requires trained people who can work for only relatively short periods of time. The electronic noses are easy to build, provide short anal. times, in real time and online, and show high sensitivity and selectivity to the tested odorants. These systems are non-destructive techniques used to characterize odorants in diverse applications linked with the quality of life such as: control of foods, environmental quality, citizen security or clin. diagnostics. However, there is much research still to be done esp. with regard to new materials and sensors technol., data processing, interpretation and validation of results. This work examines the main features of modern electronic noses and their most important applications in the environmental, and security fields. The above mentioned main components of an electronic nose (sample handling system, more advanced materials and methods for sensing, and data processing system) are described. Finally, some interesting remarks concerning the strengths and weaknesses of electronic noses in the different applications are also mentioned.
- 152Laor, Y.; Parker, D.; Pagé, T. Measurement, Prediction, and Monitoring of Odors in the Environment: A Critical Review Rev. Chem. Eng. 2014, 30, 139– 166 DOI: 10.1515/revce-2013-0026Google ScholarThere is no corresponding record for this reference.
- 153Capelli, L.; Sironi, S.; Del Rosso, R. Electronic Noses for Environmental Monitoring Applications Sensors 2014, 14, 19979– 20007 DOI: 10.3390/s141119979Google Scholar153https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2MXitVWmsLc%253D&md5=7afbe49bc1768d7339cf50038b925b38Electronic noses for environmental monitoring applicationsCapelli, Laura; Sironi, Selena; Del Rosso, RenatoSensors (2014), 14 (11), 19979-20007, 29 pp.CODEN: SENSC9; ISSN:1424-8220. (MDPI AG)A review. Electronic nose applications in environmental monitoring are nowadays of great interest, because of the instruments' proven capability of recognizing and discriminating between a variety of different gases and odors using just a small no. of sensors. Such applications in the environmental field include anal. of parameters relating to environmental quality, process control, and verification of efficiency of odor control systems. This article reviews the findings of recent scientific studies in this field, with particular focus on the abovementioned applications. In general, these studies prove that electronic noses are mostly suitable for the different applications reported, esp. if the instruments are specifically developed and fine-tuned. As a general rule, literature studies also discuss the crit. aspects connected with the different possible uses, as well as research regarding the development of effective solns. However, currently the main limit to the diffusion of electronic noses as environmental monitoring tools is their complexity and the lack of specific regulation for their standardization, as their use entails a large no. of degrees of freedom, regarding for instance the training and the data processing procedures.
- 154Di Natale, C.; Paolesse, R.; Martinelli, E.; Capuano, R. Solid-State Gas Sensors for Breath Analysis: A Review Anal. Chim. Acta 2014, 824, 1– 7 DOI: 10.1016/j.aca.2014.03.014Google Scholar154https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2cXlt1Sgt7c%253D&md5=3537987fc5dfd5f2bd6f2ab3fc7cbd25Solid-state gas sensors for breath analysis: A reviewDi Natale, Corrado; Paolesse, Roberto; Martinelli, Eugenio; Capuano, RosamariaAnalytica Chimica Acta (2014), 824 (), 1-17CODEN: ACACAM; ISSN:0003-2670. (Elsevier B.V.)A review. The anal. of volatile compds. is an efficient method to appraise information about the chem. compn. of liqs. and solids. This principle is applied to several practical applications, such as food anal. where many important features (e.g. freshness) can be directly inferred from the anal. of volatile compds. The same approach can also be applied to a human body where the volatile compds., collected from the skin, the breath or in the headspace of fluids, might contain information that could be used to diagnose several kinds of diseases. In particular, breath is widely studied and many diseases can be potentially detected from breath anal.The most fascinating property of breath anal. is the non-invasiveness of the sample collection. Solid-state sensors are considered the natural complement to breath anal., matching the non-invasiveness with typical sensor features such as low-cost, easiness of use, portability, and the integration with the information networks. Sensors based breath anal. is then expected to dramatically extend the diagnostic capabilities enabling the screening of large populations for the early diagnosis of pathologies.In the last years there has been an increased attention to the development of sensors specifically aimed to this purpose. These investigations involve both specific sensors designed to detect individual compds. and non-specific sensors, operated in array configurations, aimed at clustering subjects according to their health conditions. In this paper, the recent significant applications of these sensors to breath anal. are reviewed and discussed.
- 155Fung, A. O.; Mykhaylova, N. Analysis of Airborne Biomarkers for Point-of-Care Diagnostics J. Lab. Autom. 2014, 19, 225– 247 DOI: 10.1177/2211068213517119Google Scholar155https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A280%3ADC%252BC2czotFKgsA%253D%253D&md5=14fe3c4d10aafc0c92eaca280d0d55f2Analysis of Airborne Biomarkers for Point-of-Care DiagnosticsFung Andrew O; Mykhaylova NataliaJournal of laboratory automation (2014), 19 (3), 225-47 ISSN:.Treatable diseases continue to exact a heavy burden worldwide despite powerful advances in treatment. Diagnostics play crucial roles in the detection, management, and ultimate prevention of these diseases by guiding the allocation of precious medical resources. Motivated by globalization and evolving disease, and enabled by advances in molecular pathology, the scientific community has produced an explosion of research on miniaturized integrated biosensor platforms for disease detection. Low-cost, automated tests promise accessibility in low-resource settings by loosening constraints around infrastructure and usability. To address the challenges raised by invasive and intrusive sample collection, researchers are exploring alternative biomarkers in various specimens. Specifically, patient-generated airborne biomarkers suit minimally invasive collection and automated analysis. Disease biomarkers are known to exist in aerosols and volatile compounds in breath, odor, and headspace, media that can be exploited for field-ready diagnostics. This article reviews global disease priorities and the characteristics of low-resource settings. It surveys existing technologies for the analysis of bioaerosols and volatile organic compounds, and emerging technologies that could enable their translation to the point of care. Engineering advances promise to enable appropriate diagnostics by detecting chemical and microbial markers. Nonetheless, further innovation and cost reduction are needed for these technologies to broadly affect global health.
- 156Marco, S. The Need for External Validation in Machine Olfaction: Emphasis on Health-Related Applications Chemosensors and Chemoreception Anal. Bioanal. Chem. 2014, 406, 3941– 3956 DOI: 10.1007/s00216-014-7807-7Google Scholar156https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2cXnslOns7k%253D&md5=f0c40461a24efe949bb96d6c7651dc69The need for external validation in machine olfaction: emphasis on health-related applicationsMarco, SantiagoAnalytical and Bioanalytical Chemistry (2014), 406 (16), 3941-3956CODEN: ABCNBP; ISSN:1618-2642. (Springer)Over the last two decades, electronic nose research has produced thousands of research works. Many of them were describing the ability of the e-nose technol. to solve diverse applications in domains ranging from food technol. to safety, security, or health. It is, in fact, in the biomedical field where e-nose technol. is finding a research niche in the last years. Although few success stories exist, most described applications never found the road to industrial or clin. exploitation. Most described methodologies were not reliable and were plagued by numerous problems that prevented practical application beyond the lab. This work emphasizes the need of external validation in machine olfaction. I describe some statistical and methodol. pitfalls of the e-nose practice and I give some best practice recommendations for researchers in the field. [Figure not available: see fulltext.].
- 157Śliwińska, M.; Wiśniewska, P.; Dymerski, T.; Namieśnik, J.; Wardencki, W. Food Analysis Using Artificial Senses J. Agric. Food Chem. 2014, 62, 1423– 1448 DOI: 10.1021/jf403215yGoogle Scholar157https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2cXhtV2gu7w%253D&md5=95bea2126612a40b6233ffa9d7383d85Food analysis using artificial sensesSliwinska, Magdalena; Wisniewska, Paulina; Dymerski, Tomasz; Namiesnik, Jacek; Wardencki, WaldemarJournal of Agricultural and Food Chemistry (2014), 62 (7), 1423-1448CODEN: JAFCAU; ISSN:0021-8561. (American Chemical Society)A review. Nowadays, consumers are paying great attention to the characteristics of food such as smell, taste, and appearance. This motivates scientists to imitate human senses using devices known as electronic senses. These include electronic noses, electronic tongues, and computer vision. Thanks to the utilization of various sensors and methods of signal anal., artificial senses are widely applied in food anal. for process monitoring and detg. the quality and authenticity of foods. This paper summarizes achievements in the field of artificial senses. It includes a brief history of these systems, descriptions of most commonly used sensors (conductometric, potentiometric, amperometric/voltammetric, impedimetric, colorimetric, piezoelec.), data anal. methods (for example, artificial neural network (ANN), principal component anal. (PCA), model CIE L*a*b*), and application of artificial senses to food anal., in particular quality control, authenticity and falsification assessment, and monitoring of prodn. processes.
- 158Queralto, N.; Berliner, A. N.; Goldsmith, B.; Martino, R.; Rhodes, P.; Lim, S. H. Detecting Cancer by Breath Volatile Organic Compound Analysis: A Review of Array-Based Sensors J. Breath Res. 2014, 8, 027112 DOI: 10.1088/1752-7155/8/2/027112Google Scholar158https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2MXivFSlt7k%253D&md5=7d85dbce569eda212b5f2d94b65d83fcDetecting cancer by breath volatile organic compound analysis: a review of array-based sensorsQueralto, Nuria; Berliner, Anders N.; Goldsmith, Brett; Martino, Raymond; Rhodes, Paul; Lim, Sung H.Journal of Breath Research (2014), 8 (2), 027112CODEN: JBROBW; ISSN:1752-7155. (IOP Publishing Ltd.)A review. Cancer diagnosis is typically delayed to the late stages of disease due to the asymptomatic nature of cancer in its early stages. Cancer screening offers the promise of early cancer detection, but most conventional diagnostic methods are invasive and remain ineffective at early detection. Breath anal. is, however, non-invasive and has the potential to detect cancer at an earlier stage by analyzing volatile biomarkers in exhaled breath. This paper summarizes breath sampling techniques and recent developments of various array-based sensor technologies for breath anal. Significant advancements were made by a no. of different research groups in the development of nanomaterial-based sensor arrays, and the ability to accurately distinguish cancer patients from healthy controls based on the volatile org. compds. (VOCs) in exhaled breath has been demonstrated. Optical sensors based on colorimetric sensor array technol. are also discussed, where preliminary clin. studies suggest that metabolic VOC profiles could be used to accurately diagnose various forms of lung cancer. Recent studies have demonstrated the potential of using metabolic VOCs for cancer detection, but further standardization and validation is needed before breath anal. can be widely adopted as a clin. useful tool.
- 159Taivans, I.; Bukovskis, M.; Strazda, G.; Jurka, N. Breath Testing as a Method for Detecting Lung Cancer Expert Rev. Anticancer Ther. 2014, 14, 121– 123 DOI: 10.1586/14737140.2013.866044Google Scholar159https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2cXht1Omsbg%253D&md5=14988d8e63ae8631acdbcd805f6ee358Breath testing as a method for detecting lung cancerTaivans, Immanuels; Bukovskis, Maris; Strazda, Gunta; Jurka, NormundsExpert Review of Anticancer Therapy (2014), 14 (2), 121-123CODEN: ERATBJ; ISSN:1473-7140. (Informa Healthcare)A review. Early diagnosis of lung cancer is important due to high mortality in late stages of the disease. An ideal approach for population screening could be the breath anal., due to its non-invasiveness, simplicity and cheapness. Using sensitive methods of anal. like gas chromatog./mass spectrometry in exhaled air of cancer patients were discovered some volatile org. compds. - possible candidates for cancer markers. However, these compds. were not specific for cancer cells. At the same time, integrative approaches used to analyze the exhaled breath have demonstrated high sensitivity and specificity of this method for lung cancer diagnosis. Such integrative approaches include detection of smell prints by electronic nose or integrated anal. of wide range of volatile org. compds. detected by gas chromatog./mass spectrometry or related methods. Modern statistical pattern recognition systems like logistic regression anal., support vector machine or anal. by artificial neuronal network may improve diagnostic accuracy.
- 160Tisch, U.; Haick, H. Chemical Sensors for Breath Gas Analysis: The Latest Developments at the Breath Analysis Summit 2013 J. Breath Res. 2014, 8, 027103 DOI: 10.1088/1752-7155/8/2/027103Google Scholar160https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2MXivFSlt7w%253D&md5=a8545137866108b2a05ab61b8e122e72Chemical sensors for breath gas analysis: the latest developments at the Breath Analysis Summit 2013Tisch, Ulrike; Haick, HossamJournal of Breath Research (2014), 8 (2), 027103CODEN: JBROBW; ISSN:1752-7155. (IOP Publishing Ltd.)A review. Profiling the body chem. by means of volatile org. compds. (VOCs) in the breath opens exciting new avenues in medical diagnostics. Gas sensors could provide ideal platforms for realizing portable, hand-held breath testing devices in the near future. This review summarizes the latest developments and applications in the field of chem. sensors for diagnostic breath testing that were presented at the Breath Anal. Summit 2013 in Wallerfangen, Germany. Considerable progress has been made towards clin. applicable breath testing devices, esp. by utilizing chemo-sensitive nanomaterials. Examples of several specialized breath testing applications are presented that are either based on stand-alone nanomaterial-based sensors being highly sensitive and specific to individual breath compds. over others, or on combinations of several highly specific sensors, or on exptl. nanomaterial-based sensors arrays. Other interesting approaches include the adaptation of a com. available MOx-based sensor array to indirect breath testing applications, using a sample pre-concn. method, and the development of compact integrated GC-sensor systems. The recent trend towards device integration has led to the development of fully integrated prototypes of point-of-care devices. We describe and compare the performance of several prototypes that are based on different sensing technologies and evaluate their potential as low-cost and readily available next-generation medical devices.
- 161Boeker, P. On ’Electronic Nose’ Methodology Sens. Actuators, B 2014, 204, 2– 17 DOI: 10.1016/j.snb.2014.07.087Google Scholar161https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2cXht1KlurzE&md5=ef46d1ec6cd076ac16017ce9fa8a3996On 'Electronic Nose' methodologyBoeker, PeterSensors and Actuators, B: Chemical (2014), 204 (), 2-17CODEN: SABCEB; ISSN:0925-4005. (Elsevier B.V.)A review. Gas measurement systems used with a particular methodol. are sometimes referred to as "Electronic noses". Traditionally, these systems were based on unspecific gas sensors as detectors, but within the last years, the measurement philosophy has also been extended to fast gas chromatographs or mass spectrometers. The mere word 'electronic nose' is very seductive and has evoked the expectation of odor measurement capability of such systems. This was exacerbated by constitutive scientific publications that claimed the odor measurement capability of 'electronic noses' as a matter of course. Moreover, the biomimetic background of the electronic nose technol. was assumed as justification to address odor and aroma measurement tasks directly. But although the wealth of publications report about seemingly successful applications, the lack of practical industrial applications advises caution. Authors often tend to report selected results obtained under ideal conditions. Therefore, it is difficult or even impossible to find electronic nose systems in real routine use outside of scientific labs. The aim of this contribution is to critically review the methodol. behind electronic noses. Traditional ideas of anal. measurement processes need to be better adapted to the electronic nose approaches. Novel and better fitting terms are introduced. Moreover, the transformation and loss of information that is inevitably connected to the electronic nose methodol., is discussed in detail.
- 162Baietto, M.; Wilson, A. D. Electronic-Nose Applications for Fruit Identification, Ripeness and Quality Grading Sensors 2015, 15, 899– 931 DOI: 10.3390/s150100899Google Scholar162https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2MXkt1altLo%253D&md5=590e31e35440cc4ff6a1eb220afc1740Electronic-nose applications for fruit identification, ripeness and quality gradingBaietto, Manuela; Wilson, Alphus D.Sensors (2015), 15 (1), 899-931CODEN: SENSC9; ISSN:1424-8220. (MDPI AG)Fruits produce a wide range of volatile org. compds. that impart their characteristically distinct aromas and contribute to unique flavor characteristics. Fruit aroma and flavor characteristics are of key importance in detg. consumer acceptance in com. fruit markets based on individual preference. Fruit producers, suppliers and retailers traditionally utilize and rely on human testers or panels to evaluate fruit quality and aroma characters for assessing fruit salability in fresh markets. We explore the current and potential utilization of electronic-nose devices (with specialized sensor arrays), instruments that are very effective in discriminating complex mixts. of fruit volatiles, as new effective tools for more efficient fruit aroma analyses to replace conventional expensive methods used in fruit aroma assessments. We review the chem. nature of fruit volatiles during all stages of the agro-fruit prodn. process, describe some of the more important applications that electronic nose (e-nose) technologies have provided for fruit aroma characterizations, and summarize recent research providing e-nose data on the effectiveness of these specialized gas-sensing instruments for fruit identifications, cultivar discriminations, ripeness assessments and fruit grading for assuring fruit quality in com. markets.
- 163Gałuszka, A.; Migaszewski, Z. M.; Namieśnik, J. Moving Your Laboratories to the Field - Advantages and Limitations of the Use of Field Portable Instruments in Environmental Sample Analysis Environ. Res. 2015, 140, 593– 603 DOI: 10.1016/j.envres.2015.05.017Google Scholar163https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2MXoslOnsbw%253D&md5=a180fff1bbe6f9dc20acad5e324ace56Moving your laboratories to the field - Advantages and limitations of the use of field portable instruments in environmental sample analysisGaluszka, Agnieszka; Migaszewski, Zdzislaw M.; Namiesnik, JacekEnvironmental Research (2015), 140 (), 593-603CODEN: ENVRAL; ISSN:0013-9351. (Elsevier)The recent rapid progress in technol. of field portable instruments has increased their applications in environmental sample anal. These instruments offer a possibility of cost-effective, non-destructive, real-time, direct, on-site measurements of a wide range of both inorg. and org. analytes in gaseous, liq. and solid samples. Some of them do not require the use of reagents and do not produce any anal. waste. All these features contribute to the greenness of field portable techniques. Several stationary anal. instruments have their portable versions. The most popular ones include: gas chromatographs with different detectors (mass spectrometer (MS), flame ionization detector, photoionization detector), UV-visible and near-IR spectrophotometers, X-ray fluorescence spectrometers, ion mobility spectrometers, electronic noses and electronic tongues. The use of portable instruments in environmental sample anal. gives a possibility of on-site screening and a subsequent selection of samples for routine lab. analyses. They are also very useful in situations that require an emergency response and for process monitoring applications. However, quantification of results is still problematic in many cases. The other disadvantages include: higher detection limits and lower sensitivity than these obtained in lab. conditions, a strong influence of environmental factors on the instrument performance and a high possibility of sample contamination in the field. This paper reviews recent applications of field portable instruments in environmental sample anal. and discusses their anal. capabilities.
- 164Loutfi, A.; Coradeschi, S.; Mani, G. K.; Shankar, P.; Rayappan, J. B. B. Electronic Noses for Food Quality: A Review J. Food Eng. 2015, 144, 103– 111 DOI: 10.1016/j.jfoodeng.2014.07.019Google Scholar164https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2cXhtleju7bP&md5=64263160259e51af3cc61e31a648bdcaElectronic noses for food quality: A reviewLoutfi, Amy; Coradeschi, Silvia; Mani, Ganesh Kumar; Shankar, Prabakaran; Rayappan, John Bosco BalaguruJournal of Food Engineering (2015), 144 (), 103-111CODEN: JFOEDH; ISSN:0260-8774. (Elsevier Ltd.)This paper provides a review of the most recent works in electronic noses used in the food industry. Focus is placed on the applications within food quality monitoring i.e., meat, milk, fish, tea, coffee and wines. This paper demonstrates that there is a strong commonality between the different application area in terms of the sensors used and the data processing algorithms applied. Further, this paper provides a crit. outlook on the developments needed in this field for transitioning from research platforms to industrial instruments applied in real contexts.
- 165Scarlata, S.; Pennazza, G.; Santonico, M.; Pedone, C.; Antonelli Incalzi, R. Exhaled Breath Analysis by Electronic Nose in Respiratory Diseases Expert Rev. Mol. Diagn. 2015, 15, 933– 956 DOI: 10.1586/14737159.2015.1043895Google Scholar165https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2MXhtVKntbzE&md5=d9e76d86ad9c14c2f3ffe1b0346852cdExhaled breath analysis by electronic nose in respiratory diseasesScarlata, Simone; Pennazza, Giorgio; Santonico, Marco; Pedone, Claudio; Antonelli Incalzi, RaffaeleExpert Review of Molecular Diagnostics (2015), 15 (7), 933-956CODEN: ERMDCW; ISSN:1473-7159. (Informa Healthcare)Breath anal. via electronic nose is a technique oriented around volatile org. compd. (VOC) profiling in exhaled breath for diagnostic and prognostic purposes. This approach, when supported by methodologies for VOC identification, has been often referred to as metabolomics or breathomics. Although breath anal. may have a substantial impact on clin. practice, as it may allow early diagnosis and large-scale screening strategies while being noninvasive and inexpensive, some tech. and methodol. limitations must be solved, together with crucial interpretative issues. By integrating a review of the currently available literature with more speculative arguments about the potential interpretation and application of VOC anal., the authors aim to provide an overview of the main relevant aspects of this promising field of research.
- 166Johnson, K. J.; Rose-Pehrsson, S. L. Sensor Array Design for Complex Sensing Tasks Annu. Rev. Anal. Chem. 2015, 8, 287– 310 DOI: 10.1146/annurev-anchem-062011-143205Google Scholar166https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A280%3ADC%252BC2Mboslemsg%253D%253D&md5=a8cc51b89d5630ee52b830caff9bde36Sensor Array Design for Complex Sensing TasksJohnson Kevin J; Rose-Pehrsson Susan LAnnual review of analytical chemistry (Palo Alto, Calif.) (2015), 8 (), 287-310 ISSN:.Chemical detection in complex environments presents numerous challenges for successful implementation. Arrays of sensors are often implemented for complex chemical sensing tasks, but systematic understanding of how individual sensor response characteristics contribute overall detection system performance remains elusive, with generalized strategies for design and optimization of these arrays rarely reported and even less commonly adopted by practitioners. This review focuses on the literature of nonspecific sensor array design and optimization strategies as well as related work that may inform future efforts in complex sensing with arrays.
- 167Hagleitner, C.; Hierlemann, A.; Lange, D.; Kummer, A.; Kerness, N.; Brand, O.; Baltes, H. Smart Single-Chip Gas Sensor Microsystem Nature 2001, 414, 293– 296 DOI: 10.1038/35104535Google Scholar167https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD3MXovFemsb8%253D&md5=709e3c275dca599cef13ad2f9cd46d33Smart single-chip gas sensor microsystemHagleitner, C.; Hierlemann, A.; Lange, D.; Kummer, A.; Kerness, N.; Brane, O.; Baltes, H.Nature (London, United Kingdom) (2001), 414 (6861), 293-296CODEN: NATUAS; ISSN:0028-0836. (Nature Publishing Group)Research activity in chem. gas sensing is currently directed towards the search for highly selective (bio)chem. layer materials, and to the design of arrays consisting of different partially selective sensors that permit subsequent pattern recognition and multi-component anal. Simultaneous use of various transduction platforms was demonstrated, and the rapid development of integrated-circuit technol. has facilitated the fabrication of planar chem. sensors and sensors based on three-dimensional microelectromech. systems. Complementary metal-oxide silicon processes were previously used to develop gas sensors based on metal oxides and acoustic-wave-based sensor devices. Here the authors combine several of these developments to fabricate a smart single-chip chem. microsensor system that incorporates three different transducers (mass-sensitive, capacitive and calorimetric), all of which rely on sensitive polymeric layers to detect airborne volatile org. compds. Pull integration of the microelectronic and micromech. components on one chip permits control and monitoring of the sensor functions, and enables on-chip signal amplification and conditioning that notably improves the overall sensor performance. The circuitry also includes analog-to-digital converters, and an on-chip interface to transmit the data to off-chip recording units. The authors expect that the approach will provide a basis for the further development and optimization of gas microsystems.
- 168Kurzawski, P.; Hagleitner, C.; Hierlemann, A. Detection and Discrimination Capabilities of a Multitransducer Single-Chip Gas Sensor System Anal. Chem. 2006, 78, 6910– 6920 DOI: 10.1021/ac0610107Google ScholarThere is no corresponding record for this reference.
- 169Jin, C.; Zellers, E. T. Limits of Recognition for Binary and Ternary Vapor Mixtures Determined with Multitransducer Arrays Anal. Chem. 2008, 80, 7283– 7293 DOI: 10.1021/ac8008912Google ScholarThere is no corresponding record for this reference.
- 170Scholten, K.; Wright, L. K.; Zellers, E. T. Vapor Discrimination with Single-and Multitransducer Arrays of Nanoparticle-Coated Chemiresistors and Resonators IEEE Sens. J. 2013, 13, 2146– 2154 DOI: 10.1109/JSEN.2013.2251624Google Scholar170https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC3sXpvFegs7g%253D&md5=6c10144a266b05d153c42f117abdcf75Vapor discrimination with single- and multitransducer arrays of nanoparticle-coated chemiresistors and resonatorsScholten, Kee; Wright, Lindsay K.; Zellers, Edward T.IEEE Sensors Journal (2013), 13 (6), 2146-2154CODEN: ISJEAZ; ISSN:1530-437X. (Institute of Electrical and Electronics Engineers)This study explores whether arrays of vapor tensors assembled from two different types of transducers provide greater response diversity than arrays of a single transducer (ST) type. Calibrated sensitivities to five vapors of four chemiresistors (CRs) and four thickness-shear mode resonators (TSMR) coated with matching interface films of four different thiolate-monolayer-protected gold nanoparticles (MPNs) were considered. Test vapors consisted of toluene, nitromethane, 2-butanone, n-propanol, and n-octane. The pooled set of 40 vapor-sensor sensitivities was analyzed using principal components regression models in conjunction with Monte Carlo simulations to evaluate the classification performance with different levels of error superimposed on the sensor responses. Recognition rates (RR) were estd. for the individual vapors and their binary mixts. with virtual arrays consisting of all possible combinations of MPNs and transducer types. The best overall performance was obtained with a multitransducer (MT) array of n = 4 sensors, which provided av. RRs of 99.7% for individual vapor discrimination and 74.7% for discrimination of the 10 binary mixts. from their components, both with 5% superimposed error. MT-array RR values did not improve for n > 4. The corresponding av. RRs for the all-CR and all-TSMR 4-sensor ST arrays were both ∼97% for the individual vapors and both ∼69% for the binary mixts., resp. Results demonstrate that MT arrays can provide modestly greater diversity than ST arrays of similar dimension.
- 171Di Natale, C.; Buchholt, K.; Martinelli, E.; Paolesse, R.; Pomarico, G.; D’Amico, A.; Lundstrom, I.; Lloyd Spetz, A. Investigation of Quartz Microbalance and ChemFET Transduction of Molecular Recognition Events in a Metalloporphyrin Film Sens. Actuators, B 2009, 135, 560– 567 DOI: 10.1016/j.snb.2008.09.055Google Scholar171https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD1cXhsFCjsrbJ&md5=b482935bf3ea41d1f08e8af9848d6697Investigation of quartz microbalance and ChemFET transduction of molecular recognition events in a metalloporphyrin filmDi Natale, Corrado; Buchholt, Kristina; Martinelli, Eugenio; Paolesse, Roberto; Pomarico, Giuseppe; D'Amico, Arnaldo; Lundstrom, Ingemar; Lloyd Spetz, AnitaSensors and Actuators, B: Chemical (2009), 135 (2), 560-567CODEN: SABCEB; ISSN:0925-4005. (Elsevier B.V.)Progresses of synthetic chem. methodologies have allowed the prepn. of a great variety of artificial receptors that are particularly appealing for chem. sensor development. In this paper, we investigate and compare the properties of gas sensors based on two types of devices, quartz microbalances (QMBs) and field effect transistors (FETs), which give the means to exploit the mol. recognition events occurring in non-conductive sensing layers formed by a thiol-modified cobalt tetraphenylporphyrin (CoTPPSH). Since QMB is sensitive to mass and FET is sensitive to elec. dipoles, the resulting sensors are expected to exhibit different sensitivities and selectivities, although both based on the same sensing layer. In particular we show that the high sensitivity of CoTPPSH-coated FETs towards CO and NO is a consequence of the significant CoTPPSH elec. dipole change after the gas coordination to the metal center.
- 172Consales, M.; Cutolo, A.; Penza, M.; Aversa, P.; Cassano, G.; Giordano, M.; Cusano, A. Carbon Nanotubes Coated Acoustic and Optical VOCs Sensors: Towards the Tailoring of the Sensing Performances IEEE Trans. Nanotechnol. 2007, 6, 601– 612 DOI: 10.1109/TNANO.2007.907843Google ScholarThere is no corresponding record for this reference.
- 173Chae, I.; Lee, D.; Kim, S.; Thundat, T. Electronic Nose for Recognition of Volatile Vapor Mixtures Using a Nanopore-Enhanced Opto-Calorimetric Spectroscopy Anal. Chem. 2015, 87, 7125– 7132 DOI: 10.1021/acs.analchem.5b00915Google Scholar173https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2MXhtVOnt7zE&md5=0cfc7e31bd238688e9cfcda968621ff4Electronic Nose for Recognition of Volatile Vapor Mixtures Using a Nanopore-Enhanced Opto-Calorimetric SpectroscopyChae, Inseok; Lee, Dongkyu; Kim, Seonghwan; Thundat, ThomasAnalytical Chemistry (Washington, DC, United States) (2015), 87 (14), 7125-7132CODEN: ANCHAM; ISSN:0003-2700. (American Chemical Society)An electronic nose (e-nose) for identification and quantification of volatile org. compds. (VOCs) vapor mixts. was developed using nanopore-enhanced opto-calorimetric spectroscopy. Opto-calorimetric spectroscopy based on specific mol. vibrational transitions in the mid IR mol. fingerprint regime allows highly selective detection of VOCs vapor mixts. Nanoporous anodic aluminum oxide (AAO) microcantilevers, fabricated using a two-step anodization and simple photolithog. process, were used as highly sensitive thermomech. sensors for opto-calorimetric signal transduction. The AAO microcantilevers were optimized by fine-tuning AAO nanopore diam. to enhance their thermomech. sensitivity as well as their surface area. The thermomech. sensitivity of a bilayer AAO microcantilever with a 60. nm pore diam. was ∼1 μm/K, which is far superior to that of a bilayer plain silicon (Si) microcantilever. The adsorbed mols. of VOCs mixts. on the AAO microcantilever were fully recognized and quantified by variations of peak positions and amplitudes in the opto-calorimetric IR spectra as well as by shifts in the resonance frequency of the AAO microcantilever with the adsorbed mols. Also, identification of complex org. compds. with a real industrial sample was demonstrated by this e-nose system.
- 174Talukdar, A.; Faheem Khan, M.; Lee, D.; Kim, S.; Thundat, T.; Koley, G. Piezotransistive Transduction of Femtoscale Displacement for Photoacoustic Spectroscopy Nat. Commun. 2015, 6, 7885 DOI: 10.1038/ncomms8885Google Scholar174https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2MXhsVKhtbrM&md5=42e3837662518c58971084b6a9ad4092Piezotransistive transduction of femtoscale displacement for photoacoustic spectroscopyTalukdar, Abdul; Faheem Khan, M.; Lee, Dongkyu; Kim, Seonghwan; Thundat, Thomas; Koley, GoutamNature Communications (2015), 6 (), 7885CODEN: NCAOBW; ISSN:2041-1723. (Nature Publishing Group)Measurement of femtoscale displacements in the ultrasonic frequency range is attractive for advanced material characterization and sensing, yet major challenges remain in their reliable transduction using non-optical modalities, which can dramatically reduce the size and complexity of the transducer assembly. Here we demonstrate femtoscale displacement transduction using an AlGaN/GaN heterojunction field effect transistor-integrated GaN microcantilever that utilizes piezoelec. polarization-induced changes in two-dimensional electron gas to transduce displacement with very high sensitivity. The piezotransistor demonstrated an ultra-high gauge factor of 8,700 while consuming an extremely low power of 1.36 nW, and transduced external excitation with a superior noise-limited resoln. of 12.43 fm Hz-1/2 and an outstanding responsivity of 170 nV fm-1, which is comparable to the optical transduction limits. These extraordinary characteristics, which enabled unique detection of nanogram quantity of analytes using photoacoustic spectroscopy, can be readily exploited in realizing a multitude of novel sensing paradigms.
- 175Göpel, W. Chemical Imaging: I. Concepts and Visions for Electronic and Bioelectronic Noses Sens. Actuators, B 1998, 52, 125– 142 DOI: 10.1016/S0925-4005(98)00267-6Google Scholar175https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADyaK1cXotFehsbc%253D&md5=2d5a589cf0972f62714a171ef91b3d7eChemical imaging: I. Concepts and visions for electronic and bioelectronic nosesGopel, WolfgangSensors and Actuators, B: Chemical (1998), 52 (1-2), 125-142CODEN: SABCEB; ISSN:0925-4005. (Elsevier Science S.A.)A review with 41 refs. Perfect 'chem. imaging' aims at the time- and spatially-resolved recording of many chem. species. Subsequent comparison of results from 'chem. imaging' with calibration data will then be trained towards an identification of odor impressions, environmental or medical conditions (such as toxicity), process control parameters etc. This 'chem. imaging' can be approached by either using the well-established techniques of anal. chem. or by using a large no. of calibrated sensors and sensor systems. The latter are sometimes denoted 'electronic noses', provide an electronic approach to artificial olfaction and are considered. They offer a variety of principal advantages including the fact that calibration efforts and sizes can be minimized systematically for specific applications by fine tuning individual components of the sensor system. The paper describes a systematic to design such sensor systems. In the traditional application of chem. sensors the output of an individual chem. sensor is recorded as one 'feature'. The 1st aim towards perfect ('chem. imaging') is to det. a large no. of independent features, which span a large 'hyperspace of chem. features'. The 2nd aim is then to ext. information from this hyperspace by optimizing a feature extn. procedure towards four application-specific goals. (a) The 1st goal concerns to record certain chem. species quant. and hence aims at perfect 'chem. imaging' as defined above. (b) Alternative goals concern to record odor impressions, (c) environmental or medical conditions, (d) and process control parameters. Different kinds of calibration are wanted to ext. the wanted information from the data represented in the hyperspace of chem. sensor features. Hence, four different strategies are required to compare the features monitored by the chem. sensor systems with independent calibration stds. from (a) instruments in anal. chem., (b) human odor panels, (c) (micro-)biol. or medical tests, (d) and process parameter measurements. This adjustment of measured sensor features to calibration stds. dets. a specific type of feature extn. and pattern recognition for a specific application. This pattern recognition of exptl. recorded features is of key importance not only for these 'electronic' noses but occurs in the same way in all real 'biol.' noses. Hence, formal analogies between the tech. and biol. world of noses are obvious. It is therefore expected, that the authors' current studies on chem. sensor systems will also lead to a deeper understanding of signal processing in biol. sensor systems and vice versa. Expected synergies of comparative studies concern in particular the mol. scale understanding of (a) the elementary processes of chem. sensing, (b) human odor perception, and (c) interactions between the environment and biol. organisms. In this context, bioelectronics becomes an increasingly important discipline. By taking advantage of characteristic similarities and differences of components in tech. and biol. systems, high-performance hybrid systems will be developed in the future.
- 176Weimar, U.; Göpel, W. Chemical Imaging: II. Trends in Practical Multiparameter Sensor Systems Sens. Actuators, B 1998, 52, 143– 161 DOI: 10.1016/S0925-4005(98)00268-8Google Scholar176https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADyaK1cXotFehtr4%253D&md5=0c4104a46e195b58224fac759598f959Chemical imaging: II. Trends in practical multiparameter sensor systemsWeimar, Udo; Gopel, WolfgangSensors and Actuators, B: Chemical (1998), 52 (1-2), 143-161CODEN: SABCEB; ISSN:0925-4005. (Elsevier Science S.A.)A review with 50 refs. In most applications of chem. sensors today the original output of an individual sensor was monitored as one 'feature' (such as a certain current at a fixed potential of an electrochem. cell or a resistance of a metal oxide sensor). However, individual sensors and the detn. of individual features show limited performance only for most practical applications. Often, arrays of many sensors and an extension of the feature space are required. In this context, a general trend is to be seen now towards more perfect 'chem. imaging': the final goal is a time and spatially resolved electronic recording of many individual chem. species, of toxicity, of odor impression etc. Part I of this paper dealt with the systematics of chem. imaging with sensor systems, i.e. with theor. concepts to obtain a high-dimensional 'hyperspace of chem. features' and to deduce information from this space. This paper describes examples of already realized components of such sensor systems. They were used to increase the no. of independent chem. sensor features as a prerequisite for advanced chem. imaging. The evident 1st strategy to produce independent features by the choice of different sensor-active materials was treated in many reviews and is therefore not discussed here. The new practical approaches to produce features with corresponding prototype sensors presented in this overview are organized according to the following scheme: similar sensitive layers were studied as coatings on different transducers, the same sensitive layer was studied with a single transducer, recording occurs of different phys. properties, and the same sensitive layer and transducer and the same phys. property is recorded in different modes of sensor operation.
- 177Hierlemann, A.; Gutierrez-Osuna, R. Higher-Order Chemical Sensing Chem. Rev. 2008, 108, 563– 613 DOI: 10.1021/cr068116mGoogle Scholar177https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD1cXmtlaltg%253D%253D&md5=05203beadb0fe717702ee780990bef22Higher-order chemical sensingHierlemann, Andreas; Gutierrez-Osuna, RicardoChemical Reviews (Washington, DC, United States) (2008), 108 (2), 563-613CODEN: CHREAY; ISSN:0009-2665. (American Chemical Society)A review is given on higher-order chem. sensing systems. Arrays and systems comprising identical transducers, arrays and systems comprising different transducers, operational considerations for higher-order devices, sensor-based microanal. systems, data preprocessing, drift compensation, feature extn. from sensor dynamics, multivariate calibration, and array optimization are discussed.
- 178Potyrailo, R. A.; Surman, C.; Nagraj, N. N.; Burns, A. Materials and Transducers toward Selective Wireless Gas Sensing Chem. Rev. 2011, 111, 7315– 7354 DOI: 10.1021/cr2000477Google Scholar178https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC3MXhtFCgsb%252FJ&md5=be97e93f7f4b9171f03b2ee3fa1fd68eMaterials and transducers toward selective wireless gas sensingPotyrailo, Radislav A.; Surman, Cheryl; Nagraj, Nandini; Burns, AndrewChemical Reviews (Washington, DC, United States) (2011), 111 (11), 7315-7354CODEN: CHREAY; ISSN:0009-2665. (American Chemical Society)This review concs. on sensing materials, transduction technologies, and data anal. techniques for enhancing selectivity and sensitivity in complex environments. The authors focus on sensors that employ electromagnetic fields in the radio frequency and microwave regions of spectrum for the irinteractions with sensing materials and/or for communication with the readout components. Thus, they critically analyze sensing materials from the standpoint of their potential for selective gas response in individual wireless sensors. Using this strategy, an appropriate selection of sensing materials for monitoring of specifc gases including org. and inorg. gases, volatile org. compds., toxic industrial chems., and others can be performed.
- 179Potyrailo, R. A.; Naik, R. R. Bionanomaterials and Bioinspired Nanostructures for Selective Vapor Sensing Annu. Rev. Mater. Res. 2013, 43, 307– 334 DOI: 10.1146/annurev-matsci-071312-121710Google Scholar179https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC3sXhtlCmtbvL&md5=6522546f13d1fff1229f9bdbaab0a9d0Bionanomaterials and bioinspired nanostructures for selective vapor sensingPotyrailo, Radislav; Naik, Rajesh R.Annual Review of Materials Research (2013), 43 (), 307-334CODEN: ARMRCU; ISSN:1531-7331. (Annual Reviews)A review. At present, monitoring of air at the workplace, in urban environments, and on battlefields; exhaled air from medical patients; air in packaged food containers; and so forth can be accomplished with different types of anal. instruments. Vapor sensors have their niche in these measurements when an unobtrusive, low-power, and cost-sensitive tech. soln. is required. Unfortunately, existing vapor sensors often degrade their vapor-quantitation accuracy in the presence of high levels of interferences and cannot quantitate several components in complex gas mixts. Thus, new sensing approaches with improved sensor selectivity are required. This technol. task can be accomplished by the careful design of sensing materials with new performance properties and by coupling these materials with the suitable phys. transducers. This review is focused on the assessment of the capabilities of bionanomaterials and bioinspired nanostructures for selective vapor sensing. These sensing materials can operate with diverse transducers based on elec., mech., and optical readout principles and can provide vapor-response selectivity previously unattainable by other sensing materials. This ability for selective vapor sensing provides opportunities to significantly impact the major directions in development and application scenarios of vapor sensors.
- 180Amrani, M. E. H.; Dowdeswell, R. M.; Payne, P. A.; Persaud, K. C. An Intelligent Gas Sensing System Sens. Actuators, B 1997, 44, 512– 516 DOI: 10.1016/S0925-4005(97)00240-2Google Scholar180https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADyaK1cXos1aqsQ%253D%253D&md5=3c2af427b9fee56324af832f8e2b8205An intelligent gas sensing systemAmrani, M. E. Hassan; Dowdeswell, Richard M.; Payne, Peter A.; Persaud, Krishna C.Sensors and Actuators, B: Chemical (1997), B44 (1-3), 512-516CODEN: SABCEB; ISSN:0925-4005. (Elsevier Science S.A.)Elec. conducting org. polymers are widely used as a means of gas, odor or aroma anal. using multielement array techniques coupled with d.c. interrogation techniques. Recently the use of a.c. interrogation gives rise to improved performance. The need to use multielement arrays is much reduced since a single sector can be interrogated at a wide range of frequencies. This gives rise to much increased information content for the measurements. This paper describes the use of a.c. interrogated conducting org. polymers coupled with neural network pattern recognition techniques for a system to det. the compositional fraction of volatile vapor mixts. Expts. were conducted on binary, tertiary and quaternary mixts. of vapors and compositional fractions within 5%.
- 181Torsi, L.; Dodabalapur, A.; Sabbatini, L.; Zambonin, P. G. Multi-Parameter Gas Sensors Based on Organic Thin-Film-Transistors Sens. Actuators, B 2000, 67, 312– 316 DOI: 10.1016/S0925-4005(00)00541-4Google Scholar181https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD3cXltlWisbc%253D&md5=6760504d409b8a032c960239642ce156Multi-parameter gas sensors based on organic thin-film-transistorsTorsi, L.; Dodabalapur, A.; Sabbatini, L.; Zambonin, P. G.Sensors and Actuators, B: Chemical (2000), 67 (3), 312-316CODEN: SABCEB; ISSN:0925-4005. (Elsevier Science S.A.)Evidence is provided that an org. thin-film-transistor (OTFT) can be used as a novel gas sensor. When exposed to chem. species at room temp., four parameters can be measured: the bulk cond. of the org. thin film, the field-induced cond., the transistor threshold voltage and the field effect mobility. Measurements of these parameters may allow for recognition of mol. species.
- 182Nomani, M. W. K.; Kersey, D.; James, J.; Diwan, D.; Vogt, T.; Webb, R. A.; Koley, G. Highly Sensitive and Multidimensional Detection of NO2 Using In2O3 Thin Films Sens. Actuators, B 2011, 160, 251– 259 DOI: 10.1016/j.snb.2011.07.044Google Scholar182https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC3MXhsVGms7zM&md5=1298d414b4bd392a9dceeaaa1a82fc22Highly sensitive and multidimensional detection of NO2 using In2O3 thin filmsNomani, Md. W. K.; Kersey, D.; James, J.; Diwan, D.; Vogt, T.; Webb, Richard A.; Koley, G.Sensors and Actuators, B: Chemical (2011), 160 (1), 251-259CODEN: SABCEB; ISSN:0925-4005. (Elsevier B.V.)Reported is on the ultrasensitive and unique detection of NO2 with respect to common gaseous interferents through multi-dimensional signature anal. using In2O3 thin films as sensing layers. Sensor devices fabricated using interdigitated metal fingers of Ti/Au deposited on the In2O3 film resulted in extremely high sensitivity for NO2 mols., producing 20% change in conductance for 20 ppb NO2 in atm. conditions. Mol. adsorption induced changes in conductance (G), capacitance (C), and surface work function (.vphi.) upon exposure to various gases were measured to obtain their resp. C-G and .vphi.-G plots. The gradients of the (C-G) and (.vphi.-G) plots are distinct for individual analytes and can thus can be utilized for the specific detection of mols. Three-dimensional G-C-.vphi. signature plots for NO2 and NH3 were found to be even more effective than 2D plots in uniquely identifying the gases. Utilization of 2D signatures to analyze a binary gas mixt. was found to be quite promising with a large application potential.
- 183Schütze, A.; Gramm, A.; Rühl, T. Identification of Organic Solvents by a Virtual Multisensor System with Hierarchical Classification IEEE Sens. J. 2004, 4, 857– 863 DOI: 10.1109/JSEN.2004.833514Google Scholar183https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD2cXhtFahtrjF&md5=f7de0e241268d96ae812e07c0e87921eIdentification of organic solvents by a virtual multisensor system with hierarchical classificationSchuetze, Andreas; Gramm, Andreas; Ruehl, ThorstenIEEE Sensors Journal (2004), 4 (6), 857-863CODEN: ISJEAZ; ISSN:1530-437X. (Institute of Electrical and Electronics Engineers)To improve the selectivity of semiconductor gas sensors, temp. modulation is often used. We present a study showing the potential of this technique with information gained comparable to multisensor systems. A dynamic operating mode coupled with a low-complexity evaluation strategy allows the identification of six org. solvent vapors over a wide concn. range (2-200 ppm) with a single sensor, for example, for leak detection systems. The system features low false alarm rates; in addn., interference by other gases, such as CO or NO2, can be suppressed. For even higher identification power, switching online between different temp. cycles was studied, which provides better information for crit. decisions.
- 184Ankara, Z.; Kammerer, T.; Gramm, A.; Schütze, A. Low Power Virtual Sensor Array Based on a Micromachined Gas Sensor for Fast Discrimination between H2, CO and Relative Humidity Sens. Actuators, B 2004, 100, 240– 245 DOI: 10.1016/j.snb.2003.12.072Google Scholar184https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD2cXktVCnsrs%253D&md5=1c8113ace88b760b3bd062240a66eb9dLow power virtual sensor array based on a micromachined gas sensor for fast discrimination between H2, CO and relative humidityAnkara, Zafer; Kammerer, Thomas; Gramm, Andreas; Schutze, AndreasSensors and Actuators, B: Chemical (2004), 100 (1-2), 240-245CODEN: SABCEB; ISSN:0925-4005. (Elsevier Science B.V.)A micromachined metal oxide gas sensor operated with temp. modulation allows discrimination between air, H2 and CO in <1 s. Also, the actual humidity level and gas concn. can be estd. The authors tested gas concns. of 3-12 ppm H2 and 12-100 ppm CO at five relative humidity levels between 30 and 70%. While H2 can be identified for all concns., certain identification of CO requires concns. >20 ppm and also detn. of the relative humidity level from the sensor data.
- 185Speller, N. C.; Siraj, N.; Regmi, B. P.; Marzoughi, H.; Neal, C.; Warner, I. M. Rational Design of QCM-D Virtual Sensor Arrays Based on Film Thickness, Viscoelasticity, and Harmonics for Vapor Discrimination Anal. Chem. 2015, 87, 5156– 5166 DOI: 10.1021/ac5046824Google Scholar185https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2MXntF2gsrc%253D&md5=df5b3913916cffdac6b26da81af15667Rational Design of QCM-D Virtual Sensor Arrays Based on Film Thickness, Viscoelasticity, and Harmonics for Vapor DiscriminationSpeller, Nicholas C.; Siraj, Noureen; Regmi, Bishnu P.; Marzoughi, Hassan; Neal, Courtney; Warner, Isiah M.Analytical Chemistry (Washington, DC, United States) (2015), 87 (10), 5156-5166CODEN: ANCHAM; ISSN:0003-2700. (American Chemical Society)Herein, we demonstrate an alternative strategy for creating QCM-based sensor arrays by use of a single sensor to provide multiple responses per analyte. The sensor, which simulates a virtual sensor array (VSA), was developed by depositing a thin film of ionic liq., either 1-octyl-3-methylimidazolium bromide ([OMIm][Br]) or 1-octyl-3-methylimidazolium thiocyanate ([OMIm][SCN]), onto the surface of a QCM-D transducer. The sensor was exposed to 18 different org. vapors (alcs., hydrocarbons, chlorohydrocarbons, nitriles) belonging to the same or different homologous series. The resulting frequency shifts (Δf) were measured at multiple harmonics and evaluated using principal component anal. (PCA) and discriminant anal. (DA) which revealed that analytes can be classified with extremely high accuracy. In almost all cases, the accuracy for identification of a member of the same class, i.e., intraclass discrimination, was 100% as detd. by use of quadratic discriminant anal. (QDA). Impressively, some VSAs allowed classification of all 18 analytes tested with nearly 100% accuracy. Such results underscore the importance of utilizing lesser exploited properties that influence signal transduction. Overall, these results demonstrate excellent potential of the virtual sensor array strategy for detection and discrimination of vapor phase analytes utilizing the QCM. To the best of our knowledge, this is the first report on QCM VSAs, as well as an exptl. sensor array, that is based primarily on viscoelasticity, film thickness, and harmonics.
- 186Potyrailo, R. A.; Surman, C.; Morris, W. G.; Go, S.; Lee, Y.; Cella, J. A.; Chichak, K. S. Selective Quantitation of Vapors and Their Mixtures Using Individual Passive Multivariable RFID Sensors IEEE Int. Conf. on RFID, IEEE RFID 2010, 22– 28 DOI: 10.1109/RFID.2010.5467256Google ScholarThere is no corresponding record for this reference.
- 187Potyrailo, R. A. Polymeric Sensor Materials: Toward an Alliance of Combinatorial and Rational Design Tools ? Angew. Chem., Int. Ed. 2006, 45, 702– 723 DOI: 10.1002/anie.200500828Google ScholarThere is no corresponding record for this reference.
- 188Potyrailo, R. A.; Rajan, K.; Stoewe, K.; Takeuchi, I.; Chisholm, B.; Lam, H. Combinatorial and High-Throughput Screening of Materials Libraries: Review of State of the Art ACS Comb. Sci. 2011, 13, 579– 633 DOI: 10.1021/co200007wGoogle Scholar188https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC3MXhtFWjs7nJ&md5=86c12753832c55fde318b46552039618Combinatorial and High-Throughput Screening of Materials Libraries: Review of State of the ArtPotyrailo, Radislav; Rajan, Krishna; Stoewe, Klaus; Takeuchi, Ichiro; Chisholm, Bret; Lam, HubertACS Combinatorial Science (2011), 13 (6), 579-633CODEN: ACSCCC; ISSN:2156-8944. (American Chemical Society)A review. Rational materials design based on prior knowledge is attractive because it promises to avoid time-consuming synthesis and testing of numerous materials candidates. However with the increase of complexity of materials, the scientific ability for the rational materials design becomes progressively limited. As a result of this complexity, combinatorial and high-throughput (CHT) experimentation in materials science has been recognized as a new scientific approach to generate new knowledge. This review demonstrates the broad applicability of CHT experimentation technologies in discovery and optimization of new materials. We discuss general principles of CHT materials screening, followed by the detailed discussion of high-throughput materials characterization approaches, advances in data anal./mining, and new materials developments facilitated by CHT experimentation. We critically analyze results of materials development in the areas most impacted by the CHT approaches, such as catalysis, electronic and functional materials, polymer-based industrial coatings, sensing materials, and biomaterials.
- 189Curtarolo, S.; Hart, G. L.; Nardelli, M. B.; Mingo, N.; Sanvito, S.; Levy, O. The High-Throughput Highway to Computational Materials Design Nat. Mater. 2013, 12, 191– 201 DOI: 10.1038/nmat3568Google Scholar189https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC3sXislWju7c%253D&md5=5e116fbafda8e8437ccd0fdf7304d939The high-throughput highway to computational materials designCurtarolo, Stefano; Hart, Gus L. W.; Nardelli, Marco Buongiorno; Mingo, Natalio; Sanvito, Stefano; Levy, OhadNature Materials (2013), 12 (3), 191-201CODEN: NMAACR; ISSN:1476-1122. (Nature Publishing Group)A review. High-throughput computational materials design is an emerging area of materials science. By combining advanced thermodn. and electronic-structure methods with intelligent data mining and database construction, and exploiting the power of current supercomputer architectures, scientists generate, manage and analyze enormous data repositories for the discovery of novel materials. In this Review we provide a current snapshot of this rapidly evolving field, and highlight the challenges and opportunities that lie ahead.
- 190Mardirossian, N.; Head-Gordon, M. Exploring the Limit of Accuracy for Density Functionals Based on the Generalized Gradient Approximation: Local, Global Hybrid, and Range-Separated Hybrid Functionals with and without Dispersion Corrections J. Chem. Phys. 2014, 140, 18A527 DOI: 10.1063/1.4868117Google ScholarThere is no corresponding record for this reference.
- 191Wegst, U. G.; Bai, H.; Saiz, E.; Tomsia, A. P.; Ritchie, R. O. Bioinspired Structural Materials Nat. Mater. 2015, 14, 23– 36 DOI: 10.1038/nmat4089Google Scholar191https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2cXhvVSqtr%252FK&md5=c685610f7a7a726a4c7c07c8f269bfa0Bioinspired structural materialsWegst, Ulrike G. K.; Bai, Hao; Saiz, Eduardo; Tomsia, Antoni P.; Ritchie, Robert O.Nature Materials (2015), 14 (1), 23-36CODEN: NMAACR; ISSN:1476-1122. (Nature Publishing Group)Natural structural materials are built at ambient temp. from a fairly limited selection of components. They usually comprise hard and soft phases arranged in complex hierarchical architectures, with characteristic dimensions spanning from the nanoscale to the macroscale. The resulting materials are lightwt. and often display unique combinations of strength and toughness, but have proven difficult to mimic synthetically. Here, we review the common design motifs of a range of natural structural materials, and discuss the difficulties assocd. with the design and fabrication of synthetic structures that mimic the structural and mech. characteristics of their natural counterparts.
- 192Potyrailo, R. A.; Nagraj, N.; Surman, C.; Boudries, H.; Lai, H.; Slocik, J. M.; Kelley-Loughnane, N.; Naik, R. R. Wireless Sensors and Sensor Networks for Homeland Security Applications TrAC, Trends Anal. Chem. 2012, 40, 133– 145 DOI: 10.1016/j.trac.2012.07.013Google ScholarThere is no corresponding record for this reference.
- 193Wang, B.; Cancilla, J. C.; Torrecilla, J. S.; Haick, H. Artificial Sensing Intelligence with Silicon Nanowires for Ultraselective Detection in the Gas Phase Nano Lett. 2014, 14, 933– 938 DOI: 10.1021/nl404335pGoogle Scholar193https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2cXpt1Ggug%253D%253D&md5=3eb7b96651cd6b85ca2a4007a77a4012Artificial Sensing Intelligence with Silicon Nanowires for Ultraselective Detection in the Gas PhaseWang, Bin; Cancilla, John C.; Torrecilla, Jose S.; Haick, HossamNano Letters (2014), 14 (2), 933-938CODEN: NALEFD; ISSN:1530-6984. (American Chemical Society)The use of molecularly modified Si nanowire field effect transistors (SiNW FETs) for selective detection in the liq. phase was successfully demonstrated. In contrast, selective detection of chem. species in the gas phase was rather limited. The application of artificial intelligence on deliberately controlled SiNW FET device parameters can provide high selectivity toward specific volatile org. compds. (VOCs). The obtained selectivity allows identifying VOCs in both single-component and multicomponent environments as well as estg. the constituent VOC concns. The effect of the structural properties (functional group and/or chain length) of the mol. modifications on the accuracy of VOC detection is presented and discussed. The reported results have the potential to serve as a launching pad for the use of SiNW FET sensors in real-world counteracting conditions and/or applications.
- 194Potyrailo, R. A.; Surman, C. A Passive Radio-Frequency Identification (RFID) Gas Sensor with Self-Correction against Fluctuations of Ambient Temperature Sens. Actuators, B 2013, 185, 587– 593 DOI: 10.1016/j.snb.2013.04.107Google Scholar194https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC3sXhtVKmsLfN&md5=173a9984a666b47cfe1b234dd889c47fA passive radio-frequency identification (RFID) gas sensor with self-correction against fluctuations of ambient temperaturePotyrailo, Radislav A.; Surman, CherylSensors and Actuators, B: Chemical (2013), 185 (), 587-593CODEN: SABCEB; ISSN:0925-4005. (Elsevier B.V.)Uncontrolled fluctuations of ambient temp. in the field typically greatly reduce accuracy of gas sensors. The authors developed an approach for the self-correction against fluctuations of ambient temp. of individual gas and vapor sensors. The main innovation of the work is in the temp. correction which is accomplished without the need for a sep. uncoated ref. sensor or a sep. temp. sensor. The sensors are resonant inductor-capacitor-resistor (LCR) transducers coated with sensing materials and operated as multivariable passive (battery-free) radio frequency identification (RFID) sensors. Using the developed approach, the authors performed quantitation of an exemplary vapor at 25-40°. This tech. soln. will be attractive in numerous applications where temp. stabilization of a gas sensor or addn. of auxiliary temp. or uncoated ref. sensors is prohibitive.
- 195Amrani, M. E. H.; Persaud, K. C.; Payne, P. A. High-Frequency Measurements of Conducting Polymers: Development of a New Technique for Sensing Volatile Chemicals Meas. Sci. Technol. 1995, 6, 1500– 1507 DOI: 10.1088/0957-0233/6/10/010Google Scholar195https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADyaK2MXos12jsLo%253D&md5=c3028aa891a2817672be9b6834d2c75bHigh-frequency measurements of conducting polymers: development of a new technique for sensing volatile chemicalsAmrani, M. E. H.; Persaud, K. c.; Payne, P. A.Measurement Science & Technology (1995), 6 (10), 1500-7CODEN: MSTCEP; ISSN:0957-0233. (Institute of Physics)Elec. conducting polymers were previously used for the detection of vapors and gases by measuring the reversible change in their d.c. resistance. The sensors have very broad chem. specificity with higher sensitivity to polar chems. The change in the a.c. impedance characteristics of poly-N-(2-pyridyl)pyrrole in the presence of three different volatile chems. was studied, to det. whether measurement of multifrequency parameters could be used as the basis of chem. discrimination. The results demonstrate quantification of concn. and discrimination between the chems. tested from capacitance, conductance, resistance and dissipation factor as a function of frequency. This technique may be generally applied for discrimination between many chem. species.
- 196Hassan Amrani, M. E.; Payne, P. A.; Persaud, K. C. Multi-Frequency Measurements of Organic Conducting Polymers for Sensing of Gases and Vapours Sens. Actuators, B 1996, 33, 137– 141 DOI: 10.1016/0925-4005(96)01842-4Google ScholarThere is no corresponding record for this reference.
- 197Rheaume, J. M.; Pisano, A. P. A Review of Recent Progress in Sensing of Gas Concentration by Impedance Change Ionics 2011, 17, 99– 108 DOI: 10.1007/s11581-010-0515-1Google Scholar197https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC3MXisV2hurk%253D&md5=11d4488a0e3e8d88ccd9e0ed3f5c3e82A review of recent progress in sensing of gas concentration by impedance changeRheaume, Jonathan M.; Pisano, Albert P.Ionics (2011), 17 (2), 99-108CODEN: IONIFA; ISSN:0947-7047. (Springer)The intent of this paper is to establish the state of the art of impedance-based gas sensors. This sensor type holds promise for accurate detection of gaseous species at single ppm and below. Impedance-based sensors do not require ref. air to function, but do require calibration. Progress in the development of impedancemetric sensors for the detection of NOx, H2O, hydrocarbons, and CO is reviewed. Sensing electrodes typically consist of a noble metal or a metal oxide. YSZ is the preferred electrolyte material. Counter electrodes of Pt were common in asym. cells. These sensors typically operate at 500-700 °C and are interrogated at 10 Hz or less. Selectivity of these sensors remains a challenge esp. in lean environments. Stability is an infrequently discussed yet important concern. Equivalent circuit anal. has shed light on various detection mechanisms. The impedance changes due to analyte gases are exhibited in parameters that represent the low frequency behavior of the electrochem. system. Although the search for a detailed mechanism continues, the change in impedance due to a specific gas is generally attributed to transport processes such as adsorption and charge transfer.
- 198Su, J. J.; Beardslee, L. A.; Brand, O. Combined Chemoresistive and Chemocapacitive Microsensor Structures Transduc. Eurosens. XXVII 2013, 258– 261 DOI: 10.1109/Transducers.2013.6626751Google ScholarThere is no corresponding record for this reference.
- 199Rivadeneyra, A.; Fernández-Salmerón, J.; Agudo-Acemel, M.; López-Villanueva, J. A.; Palma, A. J.; Capitan-Vallvey, L. F. A Printed Capacitive-Resistive Double Sensor for Toluene and Moisture Sensing Sens. Actuators, B 2015, 210, 542– 549 DOI: 10.1016/j.snb.2015.01.036Google Scholar199https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2MXht1OhtLw%253D&md5=031a0ae9becd5a468958a8f4a1120c3dA printed capacitive-resistive double sensor for toluene and moisture sensingRivadeneyra, Almudena; Fernandez-Salmeron, Jose; Agudo-Acemel, Manuel; Lopez-Villanueva, Juan A.; Palma, Alberto J.; Capitan-Vallvey, Luis FerminSensors and Actuators, B: Chemical (2015), 210 (), 542-549CODEN: SABCEB; ISSN:0925-4005. (Elsevier B.V.)This paper presents a flexible printed sensor to detect two different magnitudes: toluene content and relative humidity. This device has been manufd. by using two printing techniques: inkjet printing to define the electrodes and screen printing to deposit the sensitive material. The combination in the same area of two different sensors enables the monitoring of two different gaseous chems. without interference between them. On one hand, moisture content is assocd. with changes in the elec. permittivity of the chosen substrate (capacitive effect). On the other hand, toluene concn. is measured through variations in vol. of the developed composite (resistive effect). Changes to relative humidity and toluene content have been measured in both capacitive and resistive parts as well as their responses to temp. variations.
- 200Potyrailo, R. A.; Morris, W. G. Multianalyte Chemical Identification and Quantitation Using a Single Radio Frequency Identification Sensor Anal. Chem. 2007, 79, 45– 51 DOI: 10.1021/ac061748oGoogle Scholar200https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD28Xht1Clu7rE&md5=3fce8892c94d2c65b5db467fbdb917beMultianalyte Chemical Identification and Quantitation Using a Single Radio Frequency Identification SensorPotyrailo, Radislav A.; Morris, William G.Analytical Chemistry (2007), 79 (1), 45-51CODEN: ANCHAM; ISSN:0003-2700. (American Chemical Society)An approach for multi-analyte chem. identification and quantitation using a single conventional radio frequency identification (RFID) tag adapted for chem. sensing is described. Unlike other approaches of using RFID sensors, where a special tag is designed at a much higher cost, this approach uses a conventional RFID tag, coating it with a chem.-sensitive film. For example, detection of several vapors with industrial, health, law enforcement, and security interest (ethanol, methanol, acetonitrile, water) using a single 13.56-MHz RFID tag coated with a solid polymer electrolyte sensing film, was demonstrated. By simultaneously measuring several parameters of the complex impedance from such an RFID sensor and applying multivariate statistical anal. methods, several vapors of interest were identified and quantified. With a careful selection of sensing film and measurement conditions, parts-per-billion vapor detection limits in air were achieved. These RFID sensors are very attractive as ubiquitous, multi-analyte distributed sensor networks.
- 201Potyrailo, R. A.; Surman, C. M.; Burns, A. A. P.; Nagraj, N. Highly Selective Chemical and Biological Sensors. U.S. Patent 8,542,023, 2013.Google ScholarThere is no corresponding record for this reference.
- 202Potyrailo, R. A. Method and System for Performance Enhancement of Resonant Sensors. U.S. Patent 8,736,425, 2014.Google ScholarThere is no corresponding record for this reference.
- 203Potyrailo, R. A.; Surman, C.; Monk, D.; Morris, W. G.; Wortley, T.; Vincent, M.; Diana, R.; Pizzi, V.; Carter, J.; Gach, G.; Klensmeden, S.; Ehring, H. RFID Sensors as the Common Sensing Platform for Single-Use Biopharmaceutical Manufacturing Meas. Sci. Technol. 2011, 22, 082001 DOI: 10.1088/0957-0233/22/8/082001Google ScholarThere is no corresponding record for this reference.
- 204Potyrailo, R. A.; Surman, C.; Go, S.; Lee, Y.; Sivavec, T.; Morris, W. G. Development of Radio-Frequency Identification Sensors Based on Organic Electronic Sensing Materials for Selective Detection of Toxic Vapors J. Appl. Phys. 2009, 106, 124902 DOI: 10.1063/1.3247069Google Scholar204https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD1MXhsFymtL3J&md5=633eb6da6c59728875a8844be7de2abeDevelopment of radio-frequency identification sensors based on organic electronic sensing materials for selective detection of toxic vaporsPotyrailo, Radislav A.; Surman, Cheryl; Go, Steven; Lee, Yongjae; Sivavec, Timothy; Morris, William G.Journal of Applied Physics (2009), 106 (12), 124902/1-124902/6CODEN: JAPIAU; ISSN:0021-8979. (American Institute of Physics)Development of selective vapor sensors based on a combination of org. electronic sensing materials with diverse response mechanisms to different vapors, and passive 13.56 MHz radio-frequency identification (RFID) sensors with multi-variable signal transduction is reported. Intrinsically conducting polymers, e.g., poly(3,4-ethylenedioxythiophene) and polyaniline (PANI), were applied on resonant RFID sensor antennas. These sensing materials are attractive to facilitate a crit. evaluation of this sensing concept because they exhibit only partial vapor selectivity and have well understood diverse vapor response mechanisms. The RFID antennas impedance spectra, Z(f), were inductively acquired, followed by spectral processing of their actual Zre(f) and imaginary Zim(f) portions by principal components anal. Typically measured 1σ noise levels in frequency and impedance magnitude measurements were 60 Hz and 0.025 Ω, resp. These low noise levels and high sensitivity of the resonant RFID sensor structures resulted in NH3 detns. with a 3σ detection limit down to 20 ppb. This achieved detection limit was 25-50-fold better than chemoresistor sensors based on PANI films and nanowires. (c) 2009 American Institute of Physics.
- 205Potyrailo, R. A.; Mouquin, H.; Morris, W. G. Position-Independent Chemical Quantitation with Passive 13.56-MHz Radio Frequency Identification (RFID) Sensors Talanta 2008, 75, 624– 628 DOI: 10.1016/j.talanta.2007.06.023Google ScholarThere is no corresponding record for this reference.
- 206Liu, Y.; Lei, Y. Pt-CeO2 Nanofibers Based High-Frequency Impedancemetric Gas Sensor for Selective CO and C3H8 Detection in High-Temperature Harsh Environment Sens. Actuators, B 2013, 188, 1141– 1147 DOI: 10.1016/j.snb.2013.07.069Google Scholar206https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC3sXhs1Sgtb3F&md5=835cc5c5e9e1a42781571660b08c377bPt-CeO2 nanofibers based high-frequency impedancemetric gas sensor for selective CO and C3H8 detection in high-temperature harsh environmentLiu, Yixin; Lei, YuSensors and Actuators, B: Chemical (2013), 188 (), 1141-1147CODEN: SABCEB; ISSN:0925-4005. (Elsevier B.V.)High-temp. gas sensors are highly demanded to improve the combustion efficiency and reduce the emission of pollutant. In this study, Pt-CeO2 nanofibers (Pt-CeO2 NFs) were prepd. using a facile two-step synthetic route (electrospinning followed by calcination). The impedance spectroscopy of the Pt-CeO2 NFs based sensor was investigated in pure N2 and different gas mixts. (O2, CO, CO2, NO, SO2, and C3H8 balanced by N2) with various concns. at 800 °C. For the first time, the sensor without solid electrolyte was operated at high frequency (100 kHz), so that the sensor response towards O2, CO2, NO and SO2 (balanced with N2) was completely eliminated and strong reducing gases (e.g., CO and C3H8) can be selectively detected with good sensitivity, suggesting that high-frequency impedancemetric technique is a promising approach to improve the selectivity of high-temp. harsh environment gas sensors when operated at an appropriate frequency.
- 207Shuster, G.; Baltianski, S.; Tsur, Y.; Haick, H. Utility of Resistance and Capacitance Response in Sensors Based on Monolayer-Capped Metal Nanoparticles J. Phys. Chem. Lett. 2011, 2, 1912– 1916 DOI: 10.1021/jz2008648Google Scholar207https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC3MXovFKmurk%253D&md5=d8f6d701038d41c483f3de74366cfa3dUtility of Resistance and Capacitance Response in Sensors Based on Monolayer-Capped Metal NanoparticlesShuster, Gregory; Baltianski, Sioma; Tsur, Yoed; Haick, HossamJournal of Physical Chemistry Letters (2011), 2 (15), 1912-1916CODEN: JPCLCD; ISSN:1948-7185. (American Chemical Society)The authors investigate the utility of resistance and capacitance responses, as derived by impedance spectroscopy, in well-controlled and real-world applications of monolayer-capped metal nanoparticle (MCNP) sensors. Exposure of the MCNP films to well-controlled analytes showed stable sensing responses and low baseline drift of the pertinent capacitance signals, when compared with equiv. resistance signals. In contrast, exposure of the MCNP films to breath of chronic kidney disease patients under dialysis, as a representative example to real-world multicomponent mixts., showed low baseline drift but relatively scattered signals when compared with the equiv. resistance response. The authors ascribe these discrepancies to the level and fluctuating concn. of water mols. in the real-world samples.
- 208Potyrailo, R. A.; Lee, Y.; Cotero, V. E.; Dieringer, J. A. Methods for Analysis of Fluids. U.S. Patent Appl. 20140182363, 2014.Google ScholarThere is no corresponding record for this reference.
- 209Potyrailo, R. A.; Lee, Y.; Cotero, V. E.; Dieringer, J. A. Systems for Analysis of Fluids. U.S. Patent 9,097,639, 2015.Google ScholarThere is no corresponding record for this reference.
- 210Potyrailo, R. A.; Tokarev, I. Sensing Method and System. U.S. Patent Appl. 20150115983, 2015.Google ScholarThere is no corresponding record for this reference.
- 211Janata, J. Electrochemical Microsensors Proc. IEEE 2003, 91, 864– 869 DOI: 10.1109/JPROC.2003.813576Google Scholar211https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD3sXls12ku7o%253D&md5=7ae867def72ab3aceeea5486633f46f1Electrochemical microsensorsJanata, JiriProceedings of the IEEE (2003), 91 (6), 864-869CODEN: IEEPAD; ISSN:0018-9219. (Institute of Electrical and Electronics Engineers)A review. A crit. review of recent developments in electrochem. microsensors is presented. The main emphasis is on chemiresistors and potentiometric microsensors. Both types of sensors have reached a degree of considerable maturity. Apparently the main future thrust can be expected in development of microfabricated sensing arrays based on these two principles.
- 212Bauerle, J. E. Study of Solid Electrolyte Polarization by a Complex Admittance Method J. Phys. Chem. Solids 1969, 30, 2657– 2670 DOI: 10.1016/0022-3697(69)90039-0Google Scholar212https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADyaE3cXjvVajug%253D%253D&md5=a4951c07be87ed20ec9ce1ca3ad02920Solid electrolyte polarization by a complex admittance methodBauerle, James E.Journal of Physics and Chemistry of Solids (1969), 30 (12), 2657-70CODEN: JPCSAW; ISSN:0022-3697.The polarization behavior of zirconia-yttria solid electrolyte specimens with Pt electrodes has been studied over a temp. range of 400-800° and a wide range of O partial pressures. The complex admittance of these specimens was detd. over a frequency range from d.c. to 100 kHz. An anal. of these data in the complex admittance plane indicated the presence of 3 polarizations: an electrode polarization characterized by a doub le layer capacity and an effective resistance for the overall electrode reaction, 0.5O2(gas) + 2e(Pt) ↹ O2-(electrolyte); a capacitive-resistive electrolyte polarization, probably corresponding to a partial blocking of O ions at the electrolyte grain boundaries by an impurity phase there; and a pure ohmic electrolyte polarization.
- 213Matsui, N. Complex Impedance Analysis for the Development of Zirconia Oxygen Sensors Solid State Ionics 1981, 3-4, 525– 529 DOI: 10.1016/0167-2738(81)90144-2Google ScholarThere is no corresponding record for this reference.
- 214Gutiérrez, J.; Arés, L.; Horillo, M. C.; Sayago, I.; Agapito, J.; López, L. Use of Complex Impedance Spectroscopy in Chemical Sensor Characterization Sens. Actuators, B 1991, 4, 359– 363 DOI: 10.1016/0925-4005(91)80136-8Google ScholarThere is no corresponding record for this reference.
- 215Josse, F.; Lukas, R.; Zhou, R.; Schneider, S.; Everhart, D. AC-Impedance-Based Chemical Sensors for Organic Solvent Vapors Sens. Actuators, B 1996, 36, 363– 369 DOI: 10.1016/S0925-4005(97)80097-4Google Scholar215https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADyaK2sXmsFehsA%253D%253D&md5=6ac990c08892fd76fe9f7ad6ba9a9745AC-impedance-based chemical sensors for organic solvent vaporsJosse, Fabien; Lukas, Rich; Zhou, Rongnong; Schneider, Susan; Everhart, DennisSensors and Actuators, B: Chemical (1996), 36 (1-3, Proceedings of the Sixth International Meeting on Chemical Sensors, 1996), 363-369CODEN: SABCEB; ISSN:0925-4005. (Elsevier)A type of chem. sensor based on impedance spectroscopy (IS) measurements using an interdigital transducer structure on a glass substrate is studied for the detection of org. solvent mols., such as chlorinated hydrocarbons, in the gas phase. The IDT structures were coated with sensitive materials such as sol. tetrakis-CMe3 phthalocyaninatonickel(II), ethylcellulose, poly(Et acrylate), and poly(etherurethane). The target org. solvent mols. are dichloromethane, chloroform, trichloroethene, tetrachloroethene, toluene, and ethanol. The sensor responses were monitored by measuring changes in the transducer/coating composite properties upon exposure to the org. solvent mols. The sensor parameters of interest include the electrostatic capacitance, the resistance of the composite and the relaxation time, which will lead to the implementation of a multi-information sensor. Results are presented and compared for selected samples with completely reversible sensor signals at room temp. Based on the measurements, use of metal complexes can improve sensitivity and increase the signal-to-noise ratio.
- 216Ghiotti, G.; Chiorino, A.; Martinelli, G.; Carotta, M. C. Moisture Effects on Pure and Pd-Doped SnO2 Thick Films Analysed by FTIR Spectroscopy and Conductance Measurements Sens. Actuators, B 1995, 25, 520– 524 DOI: 10.1016/0925-4005(95)85112-7Google Scholar216https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADyaK2MXnsFCisr8%253D&md5=9f0a8b7ae8b5262cefb98895da6889b3Moisture effects on pure and Pd-doped SnO2 thick films analyzed by FTIR spectroscopy and conductance measurementsGhiotti, G.; Chiorino, A.; Martinelli, G.; Carotta, M. C.Sensors and Actuators, B: Chemical (1995), 25 (1-3), 520-4CODEN: SABCEB; ISSN:0925-4005. (Elsevier)Pure SnO2 and Pd /SnO2 (0.4 wt.%) pastes have been prepd. starting from SnO2 powder obtained with the procedures generally used for gas-sensor materials. The pastes are printed on 96% alumina substrates for elec. measurements and the layers detached from the support are used for Fourier-transform IR (FTIR) investigations. Conductance measurements in dry and wet air are presented together with the FTIR spectra for temps. ranging from 100 to 450 °C. By alternating wet and dry air, it has been obsd. that the conductance of pure SnO2 samples changes in a reversible way only for temps. over approx. 200 °C, while the samples catalytically treated with Pd do not present any significant irreversible component. The IR anal. on pure SnO2 samples treated in wet air at temps. above 200 °C shows the formation of a very broad absorption of electronic nature almost completely destroyed by a subsequent dry-air treatment. The absorption may be due to two families of donor levels at 01.5-0.18 and 0.45-0.50 eV, resp., from the bottom of the conduction band. Changes of the electronic absorption shape, intensity and reversibility to dry-air contact are obsd. on the same samples treated in wet air below 200 °C. These results are compared with those obtained for Pd catalytically modified materials. The conductance and impedance measurements in the presence of methane are presented for both the wet- and dry-air treated pure and Pd-doped thick films.
- 217Agilent Impedance Measurement Handbook. A Guide to Measurement Technology and Techniques, 4th ed.; Agilent Technologies: Santa Clara, CA, 2013; http://cp.literature.agilent.com/litweb/pdf/5950-3000.pdf (accessed July 27, 2016).Google ScholarThere is no corresponding record for this reference.
- 218Potyrailo, R. A.; Boudries, H.; Naik, R. R. Multivariable MHz and GHz Wireless Chem/Bio Sensors for Environmental, Industrial, and Security Applications; Proc. IMCS 2012—The 14th Int. Meet. Chem. Sen., Nürnberg, Germany, May 20–23, 2012; Elsevier: 2012; pp 399– 402.Google ScholarThere is no corresponding record for this reference.
- 219Bouvet, M.; Suisse, J. M.; Sizun, T.; Kumar, A.; Barochi, G.; De Fonseca, B.; Rossignol, J. The Multimodal Detection as a Tool for Molecular Material-Based Gas Sensing Sens. Actuators, B 2013, 187, 204– 208 DOI: 10.1016/j.snb.2012.10.083Google Scholar219https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC38Xhs12itb%252FI&md5=d683ad2ffe347dfbf885db6a12c86085The multimodal detection as a tool for molecular material-based gas sensingBouvet, M.; Suisse, J.-M.; Sizun, T.; Kumar, A.; Barochi, G.; De Fonseca, B.; Rossignol, J.Sensors and Actuators, B: Chemical (2013), 187 (), 204-208CODEN: SABCEB; ISSN:0925-4005. (Elsevier B.V.)The adsorption of a target gas on a material induces a change in several phys. characteristics, such as the dielec. const., the work function or the cond. The use of different transducers sensitive to the variation of these parameters appears to be a relevant methodol. worthy of study. In the field of sensors, mol. materials present interesting and potentially valuable features as sensing elements for real gas sensor applications. The authors summarize the different types of conductimetric transducers and also show how a mol. material-based microwave transducer can be used for gas sensing. Among conductimetric transducers, resistors were historically the most commonly exploited way for the detection and quantification of gas pollutants. Herein, the authors focus on new transducers, either based on the known OFETs, or on transducers combining two mol. materials, the p-n junctions and the brand new mol. semiconductor-doped insulator (MSDI) heterojunctions. The sensitivity of the devices is demonstrated through the detection of ammonia and ozone in the range of ppm and ppb, resp.
- 220Chen, W. T.; Stewart, K. M. E.; Mansour, R. R.; Penlidis, A. Novel Undercoupled Radio-Frequency (RF) Resonant Sensor for Gaseous Ethanol and Interferents Detection Sens. Actuators, A 2015, 230, 63– 73 DOI: 10.1016/j.sna.2015.04.008Google Scholar220https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2MXnvFeiurk%253D&md5=3346110d21d12509c3438ad82b632c58Novel undercoupled radio-frequency (RF) resonant sensor for gaseous ethanol and interferents detectionChen, W. T.; Stewart, K. M. E.; Mansour, R. R.; Penlidis, A.Sensors and Actuators, A: Physical (2015), 230 (), 63-73CODEN: SAAPEB; ISSN:0924-4247. (Elsevier B.V.)This paper introduces a novel undercoupled RF resonant sensor platform that enables gaseous phase chem. detection for passive sensor-embedded RF devices and RFIDs. The resonant sensor is implemented with an interdigital chemi-capacitor and a transmission-line inductor, thus only requiring a simple two-layer fabrication process. Its superior sensitivity at RF frequencies arises from the benefits of response amplification near resonance, as well as the shorter wavelength at radio-frequencies. Furthermore, the interdigital capacitor allows polymeric sensing materials to be directly deposited atop, thereby improving fabrication repeatability. The sensor prototypes are loaded with three different polymeric sensing materials - OV225, OV275, and SC201(SXFA) - aiming to detect certain pre-perspiratory transdermal biomarkers including gaseous phase ethanol, methanol, and benzene. Their resp. responses are recorded in terms of three distinctive RF parameters - resonant frequency shift (Δf0), response amplitude change (ΔS11), and response delay change (ΔGD11) - from which the sensitivities of these sensors are detd., and their selectivities with respect to the sample gas analytes are subsequently characterized. Finally, evaluation of the response signatures of the polymeric sensing materials to each gas analyte enables future development of sensor array systems that can distinguish desired analytes from unwanted interferents.
- 221Wudy, F.; Multerer, M.; Stock, C.; Schmeer, G.; Gores, H. J. Rapid Impedance Scanning QCM for Electrochemical Applications Based on Miniaturized Hardware and High-Performance Curve Fitting Electrochim. Acta 2008, 53, 6568– 6574 DOI: 10.1016/j.electacta.2008.04.079Google ScholarThere is no corresponding record for this reference.
- 222Niedermayer, A. O.; Reichel, E. K.; Jakoby, B. Yet Another Precision Impedance Analyzer (YAPIA)-Readout Electronics for Resonating Sensors Sens. Actuators, A 2009, 156, 245– 250 DOI: 10.1016/j.sna.2009.04.020Google Scholar222https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD1MXhsVCrsr7I&md5=a0806f6265cadb98aa2d3b59e983722fYet another precision impedance analyzer (YAPIA)-Readout electronics for resonating sensorsNiedermayer, Alexander O.; Reichel, Erwin K.; Jakoby, BernhardSensors and Actuators, A: Physical (2009), 156 (1), 245-250CODEN: SAAPEB; ISSN:0924-4247. (Elsevier B.V.)In recent years, compact and precise impedance measurement electronics have proved to be reasonable alternatives for dedicated measurement tasks like impedance measurement of resonant sensors. In this contribution, a novel design of a compact impedance analyzer is discussed, and the target application, a quartz crystal resonator (QCR) viscosity sensor for conductive liqs., as intended for the monitoring of a zeolite synthesis process aboard the International Space Station (ISS), is presented.
- 223Liu, Y.; Difoggio, R.; Sanderlin, K.; Perez, L.; Zhao, J. Measurement of Density and Viscosity of Dodecane and Decane with a Piezoelectric Tuning Fork over 298–448 K and 0.1–137.9 MPa Sens. Actuators, A 2011, 167, 347– 353 DOI: 10.1016/j.sna.2011.03.017Google Scholar223https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC3MXmtVCrsLo%253D&md5=68f4ef89dbe36651c08d5db74082893dMeasurement of density and viscosity of dodecane and decane with a piezoelectric tuning fork over 298-448 K and 0.1-137.9 MPaLiu, Yi; DiFoggio, Rocco; Sanderlin, Kerry; Perez, Louis; Zhao, JinsongSensors and Actuators, A: Physical (2011), 167 (2), 347-353CODEN: SAAPEB; ISSN:0924-4247. (Elsevier B.V.)A novel downhole d.-and-viscosity sensor has been developed utilizing a lithium niobate (LNB) piezoelec. tuning fork resonator with two embedded electrodes. The mech. flexural tuning fork resonator can be described by an elec. equiv. circuit model when it is immersed in a fluid. Based on this model, it is shown that a simple algorithm can be derived to calc. the fluid d. and viscosity simultaneously by using exptl. detd. peak frequencies of the real and imaginary components of the admittance spectra of the tuning fork. Tests conducted on the tuning fork resonator using a variety of Newtonian fluids at room temp. and atm. pressure revealed that the calcd. fluid densities and viscosities closely agreed with known fluid values. In addn., at high pressures and temps. the measured viscosities and densities of two ref. hydrocarbon fluids, dodecane and decane, agreed reasonably well with the scientific literature values over a temp. range of 298-448 K (25-175 °C) and a pressure range of 0.1-137.9 MPa (14.5 psi-20 kpsi), which are typical of downhole environments.
- 224Jiang, J.; Wang, X.; Chao, R.; Ren, Y.; Hu, C.; Xu, Z.; Liu, G. L. Smartphone Based Portable Bacteria Pre-Concentrating Microfluidic Sensor and Impedance Sensing System Sens. Actuators, B 2014, 193, 653– 659 DOI: 10.1016/j.snb.2013.11.103Google Scholar224https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2cXhtFOksbo%253D&md5=24879f0e519e52f262a34d96fd9041a4Smartphone based portable bacteria pre-concentrating microfluidic sensor and impedance sensing systemJiang, Jing; Wang, Xinhao; Chao, Ran; Ren, Yukun; Hu, Chengpeng; Xu, Zhida; Liu, Gang LoganSensors and Actuators, B: Chemical (2014), 193 (), 653-659CODEN: SABCEB; ISSN:0925-4005. (Elsevier B.V.)Portable low-cost sensors and sensing systems for the identification and quant. measurement of bacteria in field water are crit. in preventing drinking water from being contaminated by bacteria. In this article, we reported the design, fabrication and testing of a low-cost, miniaturized and sensitive bacteria sensor based on elec. impedance spectroscopy method using a smartphone as the platform. Our design of microfluidics enabled the pre-concn. of the bacteria which lowered the detection limit to 10 bacterial cells per mL. We envision that our demonstrated smartphone-based sensing system will realize highly-sensitive and rapid in-field quantification of multiple species of bacteria and pathogens.
- 225König, A.; Thongpull, K. Lab-on-Spoon - A 3-D Integrated Hand-Held Multi-Sensor System for Low-Cost Food Quality, Safety, and Processing Monitoring in Assisted-Living Systems J. Sens. Sens. Syst. 2015, 4, 63– 75 DOI: 10.5194/jsss-4-63-2015Google ScholarThere is no corresponding record for this reference.
- 226Potyrailo, R. A.; Ashe, J. M.; Hasan, S. S.; Rao, N. K.; Sundaresan, K. Systems and Methods for Monitoring Sensors. U.S. Patent 9,147,144, 2015.Google ScholarThere is no corresponding record for this reference.
- 227Potyrailo, R. A.; Pietrzykowski, M. D.; Lee, Y. Methods for Analyte Detection. U.S. Patent 9,052,263, 2015.Google ScholarThere is no corresponding record for this reference.
- 228Potyrailo, R. A.; Ashe, J. M.; Morris, W. G.; Surman, C. M. Field-Portable Impedance Reader and Methods for Making the Same. U.S. Patent 8936191, 2015.Google ScholarThere is no corresponding record for this reference.
- 229Sacristán-Riquelme, J.; Segura-Quijano, F.; Baldi, A.; Teresa Osés, M. Low Power Impedance Measurement Integrated Circuit for Sensor Applications Microelectron. J. 2009, 40, 177– 184 DOI: 10.1016/j.mejo.2008.07.003Google ScholarThere is no corresponding record for this reference.
- 230Chabowski, K.; Piasecki, T.; Dzierka, A.; Nitsch, K. Simple Wide Frequency Range Impedance Meter Based on AD5933 Integrated Circuit Metrol. Meas. Syst. 2015, 22, 13– 24 DOI: 10.1515/mms-2015-0006Google ScholarThere is no corresponding record for this reference.
- 231Hoja, J.; Lentka, G. Miniaturized Impedance Analyzer Using AD5933 Lect. Notes Impedance Spectrosc. 2015, 5, 93 DOI: 10.1201/b18134-16Google ScholarThere is no corresponding record for this reference.
- 232Simić, M. Complex Impedance Measurement System for the Frequency Range from 5 kHz to 100 kHz Key Eng. Mater. 2015, 644, 133– 136 DOI: 10.4028/www.scientific.net/KEM.644.133Google ScholarThere is no corresponding record for this reference.
- 233Ghaffari, S. A.; Caron, W.-O.; Loubier, M.; Rioux, M.; Viens, J.; Gosselin, B.; Messaddeq, Y. A Wireless Multi-Sensor Dielectric Impedance Spectroscopy Platform Sensors 2015, 15, 23572– 23588 DOI: 10.3390/s150923572Google ScholarThere is no corresponding record for this reference.
- 234Dissanayake, S.; Vanlangenberg, C.; Patel, S. V.; Mlsna, T. Conducting Absorbent Composite for Parallel Plate Chemicapacitive Microsensors with Improved Selectivity Sens. Actuators, B 2015, 206, 548– 554 DOI: 10.1016/j.snb.2014.09.069Google Scholar234https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2cXhs1Kls7nM&md5=87cd9561d93ef2daca52399232ce0a94Conducting absorbent composite for parallel plate chemicapacitive microsensors with improved selectivityDissanayake, Shamitha; Vanlangenberg, Christopher; Patel, Sanjay V.; Mlsna, ToddSensors and Actuators, B: Chemical (2015), 206 (), 548-554CODEN: SABCEB; ISSN:0925-4005. (Elsevier B.V.)Conducting absorbent composites were prepd. using two org. polymers (polar and nonpolar) mixed with conductive carbon nanoparticles and an ionic liq. (BMIPF6). The mixt. was deposited between the plates of chemicapacitive microsensors using ink-jet technol. Different coatings were characterized using SEM and DRIFTS techniques. The response magnitude for each sensor depends on numerous phenomenon but changes in permittivity of the analyte and polymer swelling dominate. The performance of individual chemicapacitive sensors were characterized through exposure to concns. of various volatile org. compds. with different functional groups in a climate controlled vapor delivery system. Sensitivity, selectivity and limits of detection, of each prepd. sensor, were compared and the discrimination power was evaluated using quadratic discriminant anal. Ionic liq. doped polymers were able to enhance the sensitivity and the selectivity of parallel plate capacitive sensors. Improved analyte classification was achieved with the ionic liq.-doped polymers (97% accuracy) over the pure polymers. This preliminary study describes the first use of polymer composites with carbon black and ionic liqs. as the absorbent dielec. layer in parallel plate microcapacitive sensors.
- 235Musio, F.; Ferrara, M. C. Low Frequency A.C. Response of Polypyrrole Gas Sensors Sens. Actuators, B 1997, 41, 97– 103 DOI: 10.1016/S0925-4005(97)80282-1Google Scholar235https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADyaK2sXlslSlu7s%253D&md5=487d76b38852b943905822830ca56018Low frequency a.c. response of polypyrrole gas sensorsMusio, Fernando; Ferrara, Maria CristinaSensors and Actuators, B: Chemical (1997), B41 (1-3), 97-103CODEN: SABCEB; ISSN:0925-4005. (Elsevier)Elec. conducting org. polymers change their cond. and relative permittivity when exposed to volatile chems. The changes depend on the frequency, the concn. and the type of the chem. In particular the frequency dependence could be used for making more selective sensors. A polypyrrole (PPY) film gas sensor was designed and constructed in order to probe it. The low frequency (20 Hz-10 KHz) a.c. response was studied when it was exposed to 200 ppm of four different vapors: methanol, acetone, Et acetate and ethanol. Response patterns to each vapor were obtained by varying the measurement frequencies. The pattern for each vapor investigated was very different from the others, and so it has been possible to discriminate between them. The results demonstrate that it is possible to increase the sensor selectivity using the low frequency a.c. response rather than d.c. resistance change. Ageing and temp. dependence of resistance and capacitance are also reported.
- 236Potyrailo, R. A.; Morris, W. G.; Sivavec, T.; Tomlinson, H. W.; Klensmeden, S.; Lindh, K. RFID Sensors Based on Ubiquitous Passive 13.56-MHz RFID Tags and Complex Impedance Detection Wirel. Commun. Mob. Comput. 2009, 9, 1318– 1330 DOI: 10.1002/wcm.711Google ScholarThere is no corresponding record for this reference.
- 237Potyrailo, R. A.; Cella, J. A.; Surman, C. M.; Chichak, K. S.; Go, S. Sensor System and Methods for Selective Analyte Detection Using Resonance Sensor Circuit. U.S. Patent 8,364,419, 2013.Google ScholarThere is no corresponding record for this reference.
- 238Yang, R. D.; Fruhberger, B.; Park, J.; Kummel, A. C. Chemical Identification Using an Impedance Sensor Based on Dispersive Charge Transport Appl. Phys. Lett. 2006, 88, 074104 DOI: 10.1063/1.2175491Google ScholarThere is no corresponding record for this reference.
- 239Meier, D. C.; Raman, B.; Semancik, S. Detecting Chemical Hazards with Temperature-Programmed Microsensors: Overcoming Complex Analytical Problems with Multidimensional Databases? Annu. Rev. Anal. Chem. 2009, 2, 463– 484 DOI: 10.1146/annurev-anchem-060908-155127Google Scholar239https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD1MXpsFaqtrg%253D&md5=06e98b3e5660e61c3aa4ada47033dfc3Detecting chemical hazards with temperature-programmed microsensors: overcoming complex analytical problems with multidimensional databasesMeier, Douglas C.; Raman, Baranidharan; Semancik, SteveAnnual Review of Analytical Chemistry (2009), 2 (), 463-484CODEN: ARACFU; ISSN:0732-0582. (Annual Reviews Inc.)A review. Complex anal. problems, such as detecting trace quantities of hazardous chems. in challenging environments, require solns. that most effectively ext. relevant information about a sample's compn. This review presents a chemiresistive microarray-based approach to identifying targets that combines temp.-programmed elements capable of rapidly generating anal. rich data sets with statistical pattern recognition algorithms for extg. multivariate chem. fingerprints. The chem.-microsensor platform is described and its ability to generate orthogonal data through materials selection and temp. programming is discussed. Visual inspection of data sets reveals device selectivity, but statistical analyses are required to perform more complex identification tasks. Finally, recent advances in both devices and algorithms necessary to deal with practical issues involved in long-term deployment are discussed. These issues include identification and correction of signal drift, challenges surrounding real-time unsupervised operation, repeatable device manufacturability, and hierarchical classification schemes designed to deduce the chem. compn. of untrained analyte species.
- 240Weimar, U.; Göpel, W. AC Measurements on Tin Oxide Sensors to Improve Selectivities and Sensitivities Sens. Actuators, B 1995, 26, 13– 18 DOI: 10.1016/0925-4005(94)01547-UGoogle ScholarThere is no corresponding record for this reference.
- 241Potyrailo, R. A.; Tang, Z.; Bartling, B.; Nagraj, N.; Bromberg, V. Materials and Sensors for Detecting Gaseous Agents. U.S. Patent Appl. 20160187280, 2016.Google ScholarThere is no corresponding record for this reference.
- 242Snow, E. S.; Perkins, F. K. Capacitance and Conductance of Single-Walled Carbon Nanotubes in the Presence of Chemical Vapors Nano Lett. 2005, 5, 2414– 2417 DOI: 10.1021/nl051669cGoogle Scholar242https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD2MXhtFCitbrE&md5=7bccaa2fc9694372c9ff3b2a437d9fdcCapacitance and Conductance of Single-Walled Carbon Nanotubes in the Presence of Chemical VaporsSnow, Eric S.; Perkins, F. KeithNano Letters (2005), 5 (12), 2414-2417CODEN: NALEFD; ISSN:1530-6984. (American Chemical Society)Simultaneous conductance and capacitance measurements on a single-walled carbon nanotube (SWNT) network were used to ext. an intrinsic property of mol. adsorbates. Adsorbates from dil. chem. vapors produce a rapid response in both the capacitance and the conductance of the SWNT network. These responses are caused by a combination of two distinct physiochem. properties of the adsorbates: charge transfer and polarizability. The ratio of the conductance response to the capacitance response is a concn.-independent intrinsic property of a chem. vapor that can assist in its identification.
- 243Potyrailo, R. A.; Boudries, H.; Lai, H.; Nagraj, N.; Tang, Z.; Surman, C.; Morris, W. G.; Ashe, J.; Lam, H.Toward Passive Radio Frequency Identification (RFID) Sensors for Detection of Chemical Warfare Agents, Explosives, Oxidizers, and Toxic Industrial Chemicals; 2011 Chem. Biol. Defense Sci. Technol. (CBD S&T) Conf.: 2011; M19-012.Google ScholarThere is no corresponding record for this reference.
- 244Nagraj, N.; Slocik, J. M.; Phillips, D. M.; Kelley-Loughnane, N.; Naik, R. R.; Potyrailo, R. A. Selective Sensing of Vapors of Similar Dielectric Constants Using Peptide-Capped Gold Nanoparticles on Individual Multivariable Transducers Analyst 2013, 138, 4334– 4339 DOI: 10.1039/c3an00088eGoogle Scholar244https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC3sXhtVaksLjL&md5=7e70a694738a61b499794aee155d3ab6Selective sensing of vapors of similar dielectric constants using peptide-capped gold nanoparticles on individual multivariable transducersNagraj, Nandini; Slocik, Joseph M.; Phillips, David M.; Kelley-Loughnane, Nancy; Naik, Rajesh R.; Potyrailo, Radislav A.Analyst (Cambridge, United Kingdom) (2013), 138 (15), 4334-4339CODEN: ANALAO; ISSN:0003-2654. (Royal Society of Chemistry)Peptide-capped AYSSGAPPMPPF gold nanoparticles were demonstrated for highly selective chem. vapor sensing using individual multivariable inductor-capacitor-resistor (LCR) resonators. Their multivariable response was achieved by measuring their resonance impedance spectra followed by multivariate spectral anal. Detection of model toxic vapors and chem. agent simulants, such as acetonitrile, dichloromethane and Me salicylate, was performed. Dichloromethane (dielec. const. εr = 9.1) and Me salicylate (εr = 9.0) were discriminated using a single sensor. These sensing materials coupled to multivariable transducers can provide numerous opportunities for tailoring the vapor response selectivity based on the diversity of the amino acid compn. of the peptides, and by the modulation of the nature of peptide-nanoparticle interactions through designed combinations of hydrophobic and hydrophilic amino acids.
- 245Mayorga-Martinez, C. C.; Ambrosi, A.; Eng, A. Y. S.; Sofer, Z.; Pumera, M. Metallic 1T-WS2 for Selective Impedimetric Vapor Sensing Adv. Funct. Mater. 2015, 25, 5611– 5616 DOI: 10.1002/adfm.201502223Google Scholar245https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2MXhtlSmu73L&md5=266a3e5887f7f9353a4c6bfa4f7875abMetallic 1T-WS2 for Selective Impedimetric Vapor SensingMayorga-Martinez, Carmen C.; Ambrosi, Adriano; Eng, Alex Yong Sheng; Sofer, Zdenek; Pumera, MartinAdvanced Functional Materials (2015), 25 (35), 5611-5616CODEN: AFMDC6; ISSN:1616-301X. (Wiley-VCH Verlag GmbH & Co. KGaA)Selective gas sensing is of immense importance for industrial as well as safety purposes. Metallic 1T phase transition metal dichalcogenides, such as tungsten sulfide (WS2), provide sensitive and selective platform for gas sensing. Using impedance spectroscopy distinguishable alterations can be detected on the impedance phase spectrum of interdigitated gold electrode modified with chem. exfoliated 1T-WS2 caused by different vapors. In particular, the impedance phase spectra of 1T-WS2 device present different resonant frequencies with max. around 1 Hz in the presence of methanol vapor and around 1 kHz in the presence of water vapor. Such a well-distinguished signal allows their selective detection also when they are present in a mixt. The impedance phase spectra allow the selective methanol and water vapor sensing with an impedimetric device based on 1T-WS2. This system using 1T phase of WS2 for selective gas sensing based on impedance spectroscopy opens new avenues for gas sensing and shall find wide spectra of applications.
- 246Shapardanis, S.; Hudpeth, M.; Kaya, T. Gelatin as a New Humidity Sensing Material: Characterization and Limitations AIP Adv. 2014, 4, 127132 DOI: 10.1063/1.4904724Google Scholar246https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2cXitFOjtrrE&md5=d54ab629c5f08c8f495e3688bce74b8dGelatin as a new humidity sensing material: Characterization and limitationsShapardanis, Steven; Hudpeth, Mathew; Kaya, TolgaAIP Advances (2014), 4 (12), 127132/1-127132/7CODEN: AAIDBI; ISSN:2158-3226. (American Institute of Physics)The goal of this work is to assert the utility of collagen and its denatured counterpart gelatin as cost-effective alternatives to existing sensing layers comprised of polymers. Rather than producing a material that will need to be discarded or recycled, collagen, as a byproduct of the meat and leather industry, could be repurposed. This work examines the feasibility of using collagen as a sensing layer. Planar electrodes were patterned with lift-off process to work with the natural characteristics of gelatin by utilizing metal vapor deposition, spin coating, and photolithog. Characterization methods have also been optimized through the creation of specialized humidity chambers that isolate specific characteristics such as response time, accuracy, and hysteresis. Collagen-based sensors are found to have a sensitivity to moisture in the range of 0.065 pF/%RH. Diffusion characteristics were also analyzed with the diffusion coeff. found to be 2.5 × 10-5 cm2/s. Absorption and desorption times were found to be 20 s and 8 s, resp. Hysteresis present in the data is attributed to temp. cross-sensitivity. Ultimately, the utility of collagen as a dielec. sensing material is, in part, due to its fibrous macrostructures as well its hydrophilic sites along the peptide chains. Gelatin was patterned between and below interdigitated copper electrodes and tested as a relative humidity sensor. This work shows that gelatin, which is inexpensive, widely available, and easy to process, can be an effective dielec. sensing polymer for capacitive-type relative humidity sensors. (c) 2014 American Institute of Physics.
- 247Molina-Lopez, F.; Briand, D.; De Rooij, N. F. Inkjet and Microcontact Printing of Functional Materials on Foil for the Fabrication of Pixel-Like Capacitive Vapor Microsensors Org. Electron. 2015, 16, 139– 147 DOI: 10.1016/j.orgel.2014.10.041Google Scholar247https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2cXhvVOktLrM&md5=1a77a203cc8980bf3f5a61bb386626c3Inkjet and microcontact printing of functional materials on foil for the fabrication of pixel-like capacitive vapor microsensorsMolina-Lopez, Francisco; Briand, Danick; de Rooij, Nico F.Organic Electronics (2015), 16 (), 139-147CODEN: OERLAU; ISSN:1566-1199. (Elsevier B.V.)The work presented demonstrates the utilization of micro-contact printing of self-assembled monolayers (SAMs) of gold nanoparticles (NPs) to pattern the porous thin metallic film composing the top electrode of an ultra-fast capacitive relative humidity sensor based on miniaturized parallel-plates electrodes. The rest of the device, which occupies an area of only 0.0314 mm2, is fabricated by inkjet printing stacked individual drops of functional materials, namely gold NPs for the bottom electrode and a polymeric humidity sensing layer, on a polymeric foil. Compared to other printing methods, the use of microcontact printing to pattern the top electrode enables the additive transfer of a solvent-free metallic layer that does not interact chem. with the sensing layer, permitting the thinning of the latter without risk of short-circuits between electrodes, and broadening the range of usable sensing materials for detection of other gases. Thinning the sensing layer yields to ultra-fast response devices with high values of capacitance and sensitivity per surface area. The fabrication process is compatible with low heat-resistant polymeric substrates and scalable to large-area and large-scale fabrication, foreseeing the development of low-cost vapor sensing sheets with high space-time resoln., where every sensor would correspond to a pixel of a large array.
- 248Skotadis, E.; Mousadakos, D.; Katsabrokou, K.; Stathopoulos, S.; Tsoukalas, D. Flexible Polyimide Chemical Sensors Using Platinum Nanoparticles Sens. Actuators, B 2013, 189, 106– 112 DOI: 10.1016/j.snb.2013.01.046Google Scholar248https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC3sXisVarsLg%253D&md5=b660e5c7587ad0b04815cceec84b6dd2Flexible polyimide chemical sensors using platinum nanoparticlesSkotadis, E.; Mousadakos, D.; Katsabrokou, K.; Stathopoulos, S.; Tsoukalas, D.Sensors and Actuators, B: Chemical (2013), 189 (), 106-112CODEN: SABCEB; ISSN:0925-4005. (Elsevier B.V.)Platinum nanoparticles without any prior chem. modification and poly(2-hydroxyethyl methacrylate) (PHEMA) have been employed as the transducing and gas sensitive layer resp. for this flexible chem. sensing application. Using a modified magnetron sputtering technique, gas phase platinum nanoparticles have been deposited on top of flexible polyimide substrates. The surface d. of such nanoparticle films can be controlled via the overall deposition time, producing devices of varying cond. A layer of PHEMA polymer (500-700 nm thick) has been ink-jet printed on top of the nanoparticle film finalizing the sensor's fabrication. By exposing the sensor in ethanol or humidity vapors a change in the film's resistance or capacitance is obsd. facilitating the detection of such gases. The performance of these sensors has been connected with the nanoparticle film resistance.
- 249Oikonomou, P.; Botsialas, A.; Olziersky, A.; Goustouridis, D.; Speliotis, A.; Raptis, I.; Sanopoulou, M. Chemocapacitive Sensor Arrays on Si Substrate: Towards the Hybrid Integration with Read-out Electronics Microelectron. Eng. 2014, 119, 11– 15 DOI: 10.1016/j.mee.2014.02.007Google Scholar249https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2cXhsVOhurfF&md5=8f4fa5ba13d8ffa8b877fdf4c63e88c5Chemocapacitive sensor arrays on Si substrate: Towards the hybrid integration with read-out electronicsOikonomou, P.; Botsialas, A.; Olziersky, A.; Goustouridis, D.; Speliotis, A.; Raptis, I.; Sanopoulou, M.Microelectronic Engineering (2014), 119 (), 11-15CODEN: MIENEF; ISSN:0167-9317. (Elsevier B.V.)Chemocapacitors, i.e. capacitors where the dielec. layer is a polymeric layer with selective sorption of certain analytes, are extensively used in the monitoring of the environmental humidity and of other volatile analytes. The specifics of the detecting mechanism have been found to rely on a combination of interactions arising from vapor sorption, polymer swelling, and morphol. changes. The aim of the present work is to develop a fabrication procedure of InterDigitated Electrodes (IDEs) with high sensing performance. The IDEs layout has been optimized in terms of sensing performance and is in accordance with the read-out electronics specifications. The realization and evaluation of chemocapacitor arrays integrated with read-out electronic module in the presence of various analyte vapors is demonstrated in lab. environment. The analytes employed in the present study are typical for the printing industry of flexible packaging.
- 250Adhikari, B.; Majumdar, S. Polymers in Sensor Applications Prog. Polym. Sci. 2004, 29, 699– 766 DOI: 10.1016/j.progpolymsci.2004.03.002Google Scholar250https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD2cXkvFyms7c%253D&md5=b70b8d7ad9c3c0ce8e79302234e0db00Polymers in sensor applicationsAdhikari, Basudam; Majumdar, SarmishthaProgress in Polymer Science (2004), 29 (7), 699-766CODEN: PRPSB8; ISSN:0079-6700. (Elsevier Science B.V.)A review on the use of polymers as gas sensors, pH sensors, ion-selective sensors, humidity sensors, biosensor devices, etc. Better selectivity and rapid measurements have been achieved by replacing classical sensor materials with polymers involving nanotechnol. and exploiting either the intrinsic or extrinsic functions of polymers. Semiconductors, semiconducting metal oxides, solid electrolytes, ionic membranes, and org. semiconductors have been the classical materials for sensor devices. Both intrinsically conducting polymers and non-conducting polymers are used in sensor devices. Polymers used in sensor devices either participate in sensing mechanisms or immobilize the component responsible for sensing the analyte. Current trends in sensor research and also challenges in future sensor research are discussed.
- 251Potyrailo, R. A.; Surman, C. M. Temperature-Independent Chemical and Biological Sensors. U.S. Patent 8,990,025, 2015.Google ScholarThere is no corresponding record for this reference.
- 252Potyrailo, R. A.Chemical and Biological Sensing in Wearable Formats; Wearable Technology Show: London, March 15–16, 2016.Google ScholarThere is no corresponding record for this reference.
- 253Ballantine, D. S., Jr.; White, R. M.; Martin, S. J.; Ricco, A. J.; Frye, G. C.; Zellers, E. T.; Wohltjen, H. Acoustic Wave Sensors: Theory, Design, and Physico-Chemical Applications; Academic Press: San Diego, CA, 1997.Google ScholarThere is no corresponding record for this reference.
- 254McGill, R. A.; Chung, R.; Chrisey, D. B.; Dorsey, P. C.; Matthews, P.; Piqué, A.; Mlsna, T. E.; Stepnowski, J. L. Performance Optimization of Surface Acoustic Wave Chemical Sensors IEEE Trans. Ultrason., Ferroelect., Freq. Control 1998, 45, 1370– 1380 DOI: 10.1109/58.726464Google ScholarThere is no corresponding record for this reference.
- 255Houser, E. J.; Mlsna, T. E.; Nguyen, V. K.; Chung, R.; Mowery, R. L.; McGill, R. A. Rational Materials Design of Sorbent Coatings for Explosives: Applications with Chemical Sensors Talanta 2001, 54, 469– 485 DOI: 10.1016/S0039-9140(00)00545-2Google Scholar255https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD3MXivFegtrg%253D&md5=6ed7191f92a7293066b8d339010dd63dRational materials design of sorbent coatings for explosives: applications with chemical sensorsHouser, E. J.; Mlsna, T. E.; Nguyen, V. K.; Chung, R.; Mowery, R. L.; Andrew McGill, R.Talanta (2001), 54 (3), 469-485CODEN: TLNTA2; ISSN:0039-9140. (Elsevier Science B.V.)A series of chemoselective polymers had been designed and synthesized to enhance the sorption properties of polymer coated chem. sensors for polynitroarom. analytes. To evaluate the effectiveness of the chemoselective coatings, a polynitroarom. vapor test bed was utilized to challenge polymer coated surface acoustic wave (SAW) devices with different explosive vapors. Dinitrotoluene detection limits were detd. to be in the <100 parts per trillion ranges. ATR-FTIR studies were used to det. the nature of the polymer-polynitroarom. analyte interactions, and confirm the presence of hydrogen-bonding between polymer pendant groups and the nitro functional groups of polynitroarom. explosive materials.
- 256Janata, J.; Josowicz, M. Conducting Polymers in Electronic Chemical Sensors Nat. Mater. 2003, 2, 19– 24 DOI: 10.1038/nmat768Google Scholar256https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD3sXnsleg&md5=c46018e59fdc8f6b8a6d89597e8eff58Conducting polymers in electronic chemical sensorsJanata, Jiri; Josowicz, MiraNature Materials (2003), 2 (1), 19-24CODEN: NMAACR; ISSN:1476-1122. (Nature Publishing Group)A review. Conducting org. polymers used as materials in fabrication of various electronic devices and as selective layers in chem. sensors are described. The conducting polymers include polyaniline, polypyrrole, poly(phenylene sulfide-phenyleneamine) as p-type semiconductors usually unstable when in the reduced state, and polythiophene which is stable even when reduced or slightly oxidized. The role of ambient gases on the stability of conducting polymers and its consequences on the performance of devices is outlined. The operation of sensors, where interactions of conducting polymers with the surrounding gases is beneficial and is the basis for the operation of the sensors. Key properties of conducting polymers, e.g., cond., structure and morphol., and work function as related to cond. are discussed, with focus on applications to electronics.
- 257Lange, U.; Roznyatovskaya, N. V.; Mirsky, V. M. Conducting Polymers in Chemical Sensors and Arrays Anal. Chim. Acta 2008, 614, 1– 26 DOI: 10.1016/j.aca.2008.02.068Google Scholar257https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD1cXks1eitL0%253D&md5=457857d2b670841fb211ff74a7445257Conducting polymers in chemical sensors and arraysLange, Ulrich; Roznyatovskaya, Nataliya V.; Mirsky, Vladimir M.Analytica Chimica Acta (2008), 614 (1), 1-26CODEN: ACACAM; ISSN:0003-2670. (Elsevier B.V.)A review. The review covers main applications of conducting polymers in chem. sensors and biosensors. The first part is focused on intrinsic and induced receptor properties of conducting polymers, such as pH sensitivity, sensitivity to inorg. ions and org. mols. as well as sensitivity to gases. Induced receptor properties can be also formed by molecularly imprinted polymn. or by immobilization of biol. receptors. Immobilization strategies are reviewed in the second part. The third part is focused on applications of conducting polymers as transducers and includes usual optical (fluorescence, SPR, etc.) and elec. (conductometric, amperometric, potentiometric, etc.) transducing techniques as well as org. chemosensitive semiconductor devices. An assembly of stable sensing structures requires strong binding of conducting polymers to solid supports. These aspects are discussed in the next part. Finally, an application of combinatorial synthesis and high-throughput anal. to the development and optimization of sensing materials is described.
- 258Hatchett, D. W.; Josowicz, M. Composites of Intrinsically Conducting Polymers as Sensing Nanomaterials Chem. Rev. 2008, 108, 746– 769 DOI: 10.1021/cr068112hGoogle Scholar258https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD1cXivF2jtw%253D%253D&md5=bcfd4329c7ecda34449148c3fa910a5eComposites of Intrinsically Conducting Polymers as Sensing NanomaterialsHatchett, David W.; Josowicz, MiraChemical Reviews (Washington, DC, United States) (2008), 108 (2), 746-769CODEN: CHREAY; ISSN:0009-2665. (American Chemical Society)A review. The fundamental and technol. incentive for intrinsically conducting polymers (ICP) composite sensors, the sensing properties, and how mol. ICP composites are made is explored. The behavior of the secondary component relative to the primary component and how the combined properties of the composite improve sensing applications is also examd. The refs. selected in the text do not reflect the chronol. of the advances in the research field within the last 7 years, and we do not claim to present every possible ref. for completeness. Rather the refs. are meant to highlight specific aspects and applications that are important in the synthesis and application of ICP composite to chem. and biosensors.
- 259Ramesh Kumar, M.; Ryman, S.; Tareq, O.; Buchanan, D. A.; Freund, M. S. Chemical Diversity in Electrochemically Deposited Conducting Polymer-Based Sensor Arrays Sens. Actuators, B 2014, 202, 600– 608 DOI: 10.1016/j.snb.2014.05.120Google Scholar259https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2cXht1aksbzM&md5=b4ebc32fdf57a7aafd37fc0715adcfdcChemical diversity in electrochemically deposited conducting polymer-based sensor arraysRamesh Kumar, M.; Ryman, Shaun; Tareq, Obaej; Buchanan, Douglas A.; Freund, Michael S.Sensors and Actuators, B: Chemical (2014), 202 (), 600-608CODEN: SABCEB; ISSN:0925-4005. (Elsevier B.V.)The mammalian olfactory system is highly complex, with more than 1000 non-specific binding receptors. The chem. diversity among these receptors yields differential responses resulting in a 'fingerprint' response pattern characteristic of a particular gas phase odorant or mixt. It is through these response-patterns that our brain perceives its chem. environment. While the concept of an electronic nose has been explored over the past several decades, the emergence of integrated circuits analogous to charge-coupled device (CCD) devices with this kind of chem. sensitivity have yet to emerge. One of the main stumbling blocks is the ability to deposit large nos. of chem. diverse sensing layers within large-scale integrated circuits. The use of electronically conducting polymers (ECP) as sensing layers are attractive since they can be electrodeposited on existing fabricated structures without the need for addnl. lithog. steps, however they are limited by the no. of chem. different monomer units available. In this study, we demonstrate the ability to significantly increase the level of diversity through the control of the dopant and the oxidn. level of the deposited polymer layers. By using two polymers, several dopants and different oxidn. states detd. by applied electrochem. potential, fifty-five chem. diverse sensing elements are produced. These results suggest that by using these orthogonal variables, a chem. diverse integrated sensor array chip can be generated through a combinatorial approach of deposition conditions.
- 260Alizadeh, N.; Pirsa, S.; Mani-Varnosfaderani, A.; Alizadeh, M. S. Design and Fabrication of Open-Tubular Array Gas Sensors Based on Conducting Polypyrrole Modified with Crown Ethers for Simultaneous Determination of Alkylamines IEEE Sens. J. 2015, 15, 4130– 4136 DOI: 10.1109/JSEN.2015.2411515Google ScholarThere is no corresponding record for this reference.
- 261Blue, R.; Vobecka, Z.; Skabara, P. J.; Uttamchandani, D. The Development of Sensors for Volatile Nitro-Containing Compounds as Models for Explosives Detection Sens. Actuators, B 2013, 176, 534– 542 DOI: 10.1016/j.snb.2012.10.088Google Scholar261https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC3sXlvVCitQ%253D%253D&md5=f3c419a3efa09ab8e9d719d042a8cf4dThe development of sensors for volatile nitro-containing compounds as models for explosives detectionBlue, Robert; Vobecka, Zuzana; Skabara, Peter J.; Uttamchandani, DeepakSensors and Actuators, B: Chemical (2013), 176 (), 534-542CODEN: SABCEB; ISSN:0925-4005. (Elsevier B.V.)Sensors capable of detecting explosives or their degrdn. products are important devices needed to safeguard citizens and infrastructure. The sensor application is reported of novel customized polymer films that have high affinity for chem. vapors contg. the nitro (NO2) group, which is found in explosives such as TNT and DNT. The localized electrochem. growth is used of these polymers to realize miniature, high-selectivity capacitive sensors based on interdigitated electrodes (IDEs). These sensors were tested for response to vapors of nitrobenzene and 2-nitrotoluene as model analytes for nitro vapors generated from explosive compds. The sensors were demonstrated to be reversible and to have a very high selectivity to nitro-bearing compds. In the ppm concn. region, the sensors exhibited a linear response up to three orders of magnitude higher to nitro groups than to other common volatile chems. found in the atm., which is the highest selectivity to nitro compds. reported from a polymer-based chemicapacitor sensor.
- 262Bai, H.; Shi, G. Gas Sensors Based on Conducting Polymers Sensors 2007, 7, 267– 307 DOI: 10.3390/s7030267Google Scholar262https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD2sXktlarsb8%253D&md5=bd154cad615f74cb03c483e59abc1e66Gas sensors based on conducting polymersBai, Hua; Shi, GaoquanSensors (2007), 7 (3), 267-307CODEN: SENSC9; ISSN:1424-8220. (Molecular Diversity Preservation International)A review. The gas sensors fabricated by using conducting polymers such as polyaniline (PAni), polypyrrole (PPy) and poly(3,4-ethylenedioxythiophene) (PEDOT) as the active layers were reviewed. This review discusses the sensing mechanism and configurations of the sensors. The factors that affect the performances of the gas sensors are also addressed. The disadvantages of the sensors and a brief prospect in this research field are discussed at the end of the review.
- 263Bouvet, M.; Gaudillat, P.; Suisse, J. M. Phthalocyanine-Based Hybrid Materials for Chemosensing J. Porphyrins Phthalocyanines 2013, 17, 913– 919 DOI: 10.1142/S1088424613300073Google Scholar263https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC3sXhsVWrs7vJ&md5=12b72a47db69850e228186c02c012981Phthalocyanine-based hybrid materials for chemosensingBouvet, Marcel; Gaudillat, Pierre; Suisse, Jean-MoiseJournal of Porphyrins and Phthalocyanines (2013), 17 (10), 913-919CODEN: JPPHFZ; ISSN:1088-4246. (World Scientific Publishing Co. Pte. Ltd.)The chem. variability of phthalocyanines allowed for synthesis of a broad range of hybrid materials. The combination of phthalocyanines or related derivs. with polymers or carbonaceous materials has led to efficient chem. sensors. Incorporation of macrocyclic mols. in hybrid materials highly modifies the structural and morphol. characteristics of the materials. Rugosity, sp. surface, and porosity are key parameters in the analyte-sensing material interactions, and these modifications highly improve the performance of chem. sensors. This is why they are particularly promising materials for the development of new chem. sensors, assocd. with electrochem., conductometric, or optical transducers. Tuning the phys. properties of phthalocyanine derivs. by processing as hybrid materials makes them extremely efficient for chem. sensor applications.
- 264Fergus, J. W. Perovskite Oxides for Semiconductor-Based Gas Sensors Sens. Actuators, B 2007, 123, 1169– 1179 DOI: 10.1016/j.snb.2006.10.051Google Scholar264https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD2sXkvFOgur8%253D&md5=b3696c90a373cb079d0b08a7d5440e7aPerovskite oxides for semiconductor-based gas sensorsFergus, Jeffrey W.Sensors and Actuators, B: Chemical (2007), 123 (2), 1169-1179CODEN: SABCEB; ISSN:0925-4005. (Elsevier B.V.)A review. The O partial pressure dependence of the point defect concn., and thus cond., in oxide semiconductors allows for their use in high-temp. gas sensors. In addn. to responding to O partial pressure, the resistance of oxide semiconductors can be affected by other gases, such as CO, hydrocarbons and EtOH, which creates opportunities for developing new sensors, but also leads to interference problems. The most common oxide used in such sensors is Sn oxide, although other simple oxides, and some mixed oxides, are also used. The focus of this paper is on the use of perovskite oxides in semiconductor-based gas sensors. The perovskite structure, with 2 differently-sized cations, is amenable to a variety of dopant addns. This flexibility allows for control of the transport and catalytic properties, which are important for improving sensor performance.
- 265Korotcenkov, G.; Han, S. D.; Cho, B. K. Material Design for Metal Oxide Chemiresistive Gas Sensors J. Sens. Sens. Techn. 2013, 22, 1– 17 DOI: 10.5369/JSST.2013.22.1.1Google ScholarThere is no corresponding record for this reference.
- 266Miller, D. R.; Akbar, S. A.; Morris, P. A. Nanoscale Metal Oxide-Based Heterojunctions for Gas Sensing: A Review Sens. Actuators, B 2014, 204, 250– 272 DOI: 10.1016/j.snb.2014.07.074Google Scholar266https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2cXht1KlurzP&md5=28d6aa763b7179b832f7a926a51fbe88Nanoscale metal oxide-based heterojunctions for gas sensing: A reviewMiller, Derek R.; Akbar, Sheikh A.; Morris, Patricia A.Sensors and Actuators, B: Chemical (2014), 204 (), 250-272CODEN: SABCEB; ISSN:0925-4005. (Elsevier B.V.)A review. Metal oxide-based resistive-type gas sensors are solid-state devices which are widely used in a no. of applications from health and safety to energy efficiency and emission control. Nanomaterials such as nanowires, nanorods, and nanoparticles have dominated the research focus in this field due to their large no. of surface sites facilitating surface reactions. Previous studies have shown that incorporating two or more metal oxides to form a heterojunction interface can have drastic effects on gas sensor performance, esp. the selectivity. Recently, these effects have been amplified by designing heterojunctions on the nano-scale. These designs have evolved from mixed com. powders and bi-layer films to finely-tuned core-shell and hierarchical brush-like nanocomposites. This review details the various morphol. classes currently available for nanostructured metal-oxide based heterojunctions and then presents the dominant electronic and chem. mechanisms that influence the performance of these materials as resistive-type gas sensors. Mechanisms explored include p-n and n-n potential barrier manipulation, n-p-n response type inversions, spill-over effects, synergistic catalytic behavior, and microstructure enhancement. Tables are presented summarizing these works specifically for SnO2, ZnO, TiO2, In2O3, Fe2O3, MoO3, Co3O4, and CdO-based nanocomposites. Recent developments are highlighted and likely future trends are explored.
- 267Kim, H.-J.; Lee, J.-H. Highly Sensitive and Selective Gas Sensors Using P-Type Oxide Semiconductors: Overview Sens. Actuators, B 2014, 192, 607– 627 DOI: 10.1016/j.snb.2013.11.005Google Scholar267https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2cXpsVaq&md5=1f056ccba1d66c1c5ecffcfd548f5853Highly sensitive and selective gas sensors using p-type oxide semiconductors: OverviewKim, Hyo-Joong; Lee, Jong-HeunSensors and Actuators, B: Chemical (2014), 192 (), 607-627CODEN: SABCEB; ISSN:0925-4005. (Elsevier B.V.)A review. High-performance gas sensors prepd. using p-type oxide semiconductors such as NiO, CuO, Cr2O3, Co3O4, and Mn3O4 are reviewed. The ionized adsorption of oxygen on p-type oxide semiconductors leads to the formation of hole-accumulation layers (HALs), and conduction occurs mainly along the near-surface HAL. Thus, the chemoresistive variations of undoped p-type oxide semiconductors are lower than those induced at the electron-depletion layers of n-type oxide semiconductors. However, highly sensitive and selective p-type oxide-semiconductor-based gas sensors can be designed either by controlling the carrier concn. through aliovalent doping or by promoting the sensing reaction of a specific gas through doping/loading the sensor material with oxide or noble metal catalysts. The junction between p- and n-type oxide semiconductors fabricated with different contact configurations can provide new strategies for designing gas sensors. P-type oxide semiconductors with distinctive surface reactivity and oxygen adsorption are also advantageous for enhancing gas selectivity, decreasing the humidity dependence of sensor signals to negligible levels, and improving recovery speed. Accordingly, p-type oxide semiconductors are excellent materials not only for fabricating highly sensitive and selective gas sensors but also valuable additives that provide new functionality in gas sensors, which will enable the development of high-performance gas sensors.
- 268Seiyama, T.; Kato, A.; Fujiishi, K.; Nagatani, M. A New Detector for Gaseous Components Using Semiconductive Thin Films Anal. Chem. 1962, 34, 1502– 1503 DOI: 10.1021/ac60191a001Google Scholar268https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADyaF38Xkslant78%253D&md5=d0920da8149fbcc4dc63e8e951aeee86New detector for gaseous components using semiconductive thin filmsSeiyama, Tetsuro; Kato, Akio; Fujiishi, Kiyoshi; Nagatani, Masanori(1962), 34 (), 1502-3CODEN: ANCHAM; ISSN:0003-2700.The adsorption and successive desorption of gases on the surface of semiconductors takes place very rapidly near 400°. Also, elec. cond. changes markedly when thin films of semiconductors, e.g. ZnO, are taken. This property is applicable to the detection of gaseous components in gas chromatography with a sensitivity about 100 times that of a thermal-cond. detector.
- 269Ishihara, T.; Kometani, K.; Mizuhara, Y.; Takita, Y. A New Type of CO2 Gas Sensor Based on Capacitance Changes Sens. Actuators, B 1991, 5, 97– 102 DOI: 10.1016/0925-4005(91)80227-BGoogle ScholarThere is no corresponding record for this reference.
- 270Herran, J.; Mandayo, G. G.; Castano, E. Solid State Gas Sensor for Fast Carbon Dioxide Detection Sens. Actuators, B 2008, 129, 705– 709 DOI: 10.1016/j.snb.2007.09.028Google Scholar270https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD1cXitVKht70%253D&md5=ad2d85ff42cc14e98e23486294eebbd4Solid state gas sensor for fast carbon dioxide detectionHerran, Jaime; Mandayo, Gemma Garcia; Castano, EnriqueSensors and Actuators, B: Chemical (2008), B129 (2), 705-709CODEN: SABCEB; ISSN:0925-4005. (Elsevier B.V.)Promising results on the behavior of BaTiO3-CuO sputtered thin films as a sensing material under CO2 atmospheres are presented. The response to carbon dioxide of BaTiO3-CuO is due to a reversible reaction based on the presence of BaCO3 in the material. The measurement of impedance changes allows to monitor the variation in CO2 concn. Resistance and capacitance changes are closely related to work function changes in the p-n heterojunction between BaTiO3 and CuO. The sensing layer thickness influence on the response and the influence of Ag as an additive in the film are also reported.
- 271Agarwal, M.; Balachandran, M. D.; Shrestha, S.; Varahramyan, K. SnO2 Nanoparticle-Based Passive Capacitive Sensor for Ethylene Detection J. Nanomater. 2012, 2012, 145406 DOI: 10.1155/2012/145406Google ScholarThere is no corresponding record for this reference.
- 272Sears, W. M.; Colbow, K.; Consadori, F. Algorithms to Improve the Selectivity of Thermally-Cycled Tin Oxide Gas Sensors Sens. Actuators 1989, 19, 333– 349 DOI: 10.1016/0250-6874(89)87084-2Google Scholar272https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADyaK3cXkt1ynur4%253D&md5=b63722fa27c55119515482f09c7754caAlgorithms to improve the selectivity of thermally-cycled tin oxide gas sensorsSears, W. M.; Colbow, K.; Consadori, FrancoSensors and Actuators (1989), 19 (4), 333-49CODEN: SEACDX; ISSN:0250-6874.The conductance of a com. SmO2 gas sensor is measured as a function of concn. for a no. of different gases under conditions of thermal cycling. This information is used to examine the criteria that could be used to improve the selectivity of detection. Different conductance-time curves (signatures) are seen for the various gases tested, which show gas-specific concn. dependences. Algorithms are presented that can distinguish the responses to C3H8, CO, or H from each other and from other gases (alcs.) over wide ranges of concn. Irreversible poisoning effects occur under long-term exposure of the sensor to strong reducing gases, such as high concns. of CO or H. However, the conditions causing poisoning do not apply in most practical applications of gas sensors.
- 273Nakata, S.; Akakabe, S.; Nakasuji, M.; Yoshikawa, K. Gas Sensing Based on a Nonlinear Response: Discrimination between Hydrocarbons and Quantification of Individual Components in a Gas Mixture Anal. Chem. 1996, 68, 2067– 2072 DOI: 10.1021/ac9510954Google Scholar273https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADyaK28Xjt1Wns7o%253D&md5=1db96ec6e1b961e4525ba2d640034381Gas Sensing Based on a Nonlinear Response: Discrimination between Hydrocarbons and Quantification of Individual Components in a Gas MixtureNakata, Satoshi; Akakabe, Sumiko; Nakasuji, Mie; Yoshikawa, KenichiAnalytical Chemistry (1996), 68 (13), 2067-2072CODEN: ANCHAM; ISSN:0003-2700. (American Chemical Society)A novel sensing system is proposed based on the multidimensional information contained in a dynamic nonlinear response. A sinusoidal temp. change was applied to a SnO2 semiconductor gas sensor, and the resulting output conductance of the sensor was analyzed by fast Fourier transformation (FFT). The higher harmonics of the FFT characterized the nonlinear properties of the response. The amplitudes of the higher harmonics of the FFT exhibit characteristic changes which depend on the chem. structure, concn., and the kinetics of adsorption and the reaction of hydrocarbon gases and arom. vapors on the sensor surface. It is possible to distinguish between gases in a gaseous mixt. with a single detector using this dynamic nonlinear response. Nonlinear responses are discussed in relation to the kinetics of the reaction at the sensor surface and the temp.-dependent barrier potential of the semiconductor.
- 274Heilig, A.; Bârsan, N.; Weimar, U.; Schweizer-Berberich, M.; Gardner, J. W.; Göpel, W. Gas Identification by Modulating Temperatures of SnO2-Based Thick Film Sensors Sens. Actuators, B 1997, 43, 45– 51 DOI: 10.1016/S0925-4005(97)00096-8Google Scholar274https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADyaK2sXotFaju74%253D&md5=eed33c812b0b137a86de9bbe0a50051bGas identification by modulating temperatures of SnO2-based thick film sensorsHeilig, A.; Barsan, N.; Weimar, U.; Schweizer-Berberich, M.; Gardner, J. W.; Gopel, W.Sensors and Actuators, B: Chemical (1997), 43 (1-3), 45-51CODEN: SABCEB; ISSN:0925-4005. (Elsevier Science S.A.)A new method is presented to identify the presence of two gases in the ambient atm. The method employs only one SnO2-based gas sensor in a sinusoidal temp. mode to perform the quant. anal. of a binary gas mixt. (CO/NO2) in air.
- 275Chakraborty, S.; Sen, A.; Maiti, H. S. Selective Detection of Methane and Butane by Temperature Modulation in Iron Doped Tin Oxide Sensors Sens. Actuators, B 2006, 115, 610– 613 DOI: 10.1016/j.snb.2005.10.046Google Scholar275https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD28XksVCrt7s%253D&md5=edbed775f5c3a6e62cc433084a2e7872Selective detection of methane and butane by temperature modulation in iron doped tin oxide sensorsChakraborty, S.; Sen, A.; Maiti, H. S.Sensors and Actuators, B: Chemical (2006), 115 (2), 610-613CODEN: SABCEB; ISSN:0925-4005. (Elsevier B.V.)In the present study we find that it is possible to develop sensors based on iron doped tin dioxide, which can detect both methane and butane (present in CNG and LPG, resp.) at a temp. of 350°C. However, the same sensors can selectively detect butane at a temp. of 425°C. Such differential behavior can be explained by considering the decrease in the no. and/or strength of Lewis acid sites on SnO2 due to Fe-doping and the role of chain length on the adsorption-desorption characteristics of alkanes. However, the incorporation of palladium as a catalyst in Fe-doped SnO2 sensors removes the typical selectivity, and the temps. of the max. response coincide for methane and butane.
- 276Meier, D. C.; Evju, J. K.; Boger, Z.; Raman, B.; Benkstein, K. D.; Martinez, C. J.; Montgomery, C. B.; Semancik, S. The Potential for and Challenges of Detecting Chemical Hazards with Temperature-Programmed Microsensors Sens. Actuators, B 2007, 121, 282– 294 DOI: 10.1016/j.snb.2006.09.050Google Scholar276https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD2sXhtValurs%253D&md5=4cae389f9e62109466aa13b356081004The potential for and challenges of detecting chemical hazards with temperature-programmed microsensorsMeier, D. C.; Evju, J. K.; Boger, Z.; Raman, B.; Benkstein, K. D.; Martinez, C. J.; Montgomery, C. B.; Semancik, S.Sensors and Actuators, B: Chemical (2007), 121 (1), 282-294CODEN: SABCEB; ISSN:0925-4005. (Elsevier B.V.)Several recent demonstrations of the abilities of micro-electromech. systems (MEMS)-based microsensor technol. to detect hazardous compds. and their simulants in a variety of background conditions are presented. In each case, two pairs of conductometric metal oxide sensors (TiO2 and SnO2) produced via chem. vapor deposition are operated using temp.-programmed sensing (TPS). NIST microdevices can utilize this operating mode to sample a wide operating temp. range (50 °C-480 °C) in a very short time (<15 s). The voluminous databases generated by this method can be analyzed using signal processing techniques, such as artificial neural networks (ANNs), to provide actionable outputs. Several examples are presented: cyclohexyl Me methylphosphonate (CMMP), a simulant for cyclosarin (GF), is detected at concns. ranging from 700 pmol/mol to 90 nmol/mol in air backgrounds ranging from 0% relative humidity (RH) to 70% RH. The chem. warfare agents (CWAs) tabun (GA), sarin (GB), and sulfur mustard (HD) are detected at 25 nmol/mol in dry air, humidified air (40% RH), and diesel fume-laden air (3.5% satn.). Finally, a selection of five toxic industrial chems. (TICs) and one chem. warfare simulant (CWS) are measured at immediate danger to life and health (IDLH) and permissible exposure limit (PEL) levels in an array of backgrounds, including seven different interferences, each at three concn. levels (from 0.1% to 2.0% satn.), with humidity ranging from 50% RH to 90% RH, and ambient temp. spanning 0 °C-40 °C. Tech. developments that have enabled the illustrated performances, as well as future directions for conductometric microsensor research aimed at meeting the various stringent demands faced in the hazardous chem. detection application sector, are described.
- 277Zhang, G.; Xie, C. A Novel Method in the Gas Identification by Using WO3 Gas Sensor Based on the Temperature-Programmed Technique Sens. Actuators, B 2015, 206, 220– 229 DOI: 10.1016/j.snb.2014.09.063Google Scholar277https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2cXhs1emtLzO&md5=d5364480788f21510600acf5578ec54dA novel method in the gas identification by using WO3 gas sensor based on the temperature-programmed techniqueZhang, Guozhu; Xie, ChangshengSensors and Actuators, B: Chemical (2015), 206 (), 220-229CODEN: SABCEB; ISSN:0925-4005. (Elsevier B.V.)Selectivity has been considered as one of the most significant performances to evaluate the practical application of the metal oxide semiconductor (MOS) gas sensor. Temp. modulation is now a commonly recognized method in enhancing the sensor selectivity as it can reflect more feature reaction information. In this paper, a novel method in the gas identification by using WO3 gas sensor based on the temp.-programmed modulation is reported. This method allows us to be capable of dynamically obtaining the temp.-dependent elec. cond. (TEC) spectra in different atmospheres. In terms of the TEC of the WO3, a rigorous method for extg. the feature parameters is presented here, which are assocd. with the gas adsorption/desorption and defect reaction mechanisms, from the differential curve d{[lnσT3/2]}/dT - T. According to the feature parameters, we can clearly figure out the gas species that cannot be accomplished by the conventional methods. The temp.-programmed modulation thus provides a fundamental method for accurately identifying the gas species and is expected aid in opening up a new way to investigate the selectivity of the MOS gas sensors.
- 278Azzarelli, J. M.; Mirica, K. A.; Ravnsbæk, J. B.; Swager, T. M. Wireless Gas Detection with a Smartphone Via RF Communication Proc. Natl. Acad. Sci. U. S. A. 2014, 111, 18162– 18166 DOI: 10.1073/pnas.1415403111Google Scholar278https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2cXitVClu7fI&md5=46fcaf6e73c73138f7d1ab204f03ec38Wireless gas detection with a smartphone via rf communicationAzzarelli, Joseph M.; Mirica, Katherine A.; Ravnsbaek, Jens B.; Swager, Timothy M.Proceedings of the National Academy of Sciences of the United States of America (2014), 111 (51), 18162-18166CODEN: PNASA6; ISSN:0027-8424. (National Academy of Sciences)Chem. sensing is of crit. importance to human health, safety, and security, yet it is not broadly implemented because existing sensors often require trained personnel, expensive and bulky equipment, and have large power requirements. This study reports the development of a smartphone-based sensing strategy that employs chemiresponsive nanomaterials integrated into the circuitry of com. near-field communication tags to achieve nonline-of-sight, portable, and inexpensive detection and discrimination of gas-phase chems. (e.g., ammonia, hydrogen peroxide, cyclohexanone, and water) at part-per-thousand and part-per-million concns.
- 279Cao, Q.; Rogers, J. A. Ultrathin Films of Single-Walled Carbon Nanotubes for Electronics and Sensors: A Review of Fundamental and Applied Aspects Adv. Mater. 2009, 21, 29– 53 DOI: 10.1002/adma.200801995Google Scholar279https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD1MXhtlChtro%253D&md5=cf6497d5553372379d030651214f579bUltrathin films of single-walled carbon nanotubes for electronics and sensors: a review of fundamental and applied aspectsCao, Qing; Rogers, John A.Advanced Materials (Weinheim, Germany) (2009), 21 (1), 29-53CODEN: ADVMEW; ISSN:0935-9648. (Wiley-VCH Verlag GmbH & Co. KGaA)A review. Ultrathin films of single-walled carbon nanotubes (SWNTs) represent an attractive, emerging class of material, with properties that can approach the exceptional elec., mech., and optical characteristics of individual SWNTs, in a format that, unlike isolated tubes, is readily suitable for scalable integration into devices. These features suggest the potential for realistic applications as conducting or semiconducting layers in diverse types of electronic, optoelectronic and sensor systems. This article reviews recent advances in assembly techniques for forming such films, modeling and exptl. work that reveals their collective properties, and engineering aspects of implementation in sensors and in electronic devices and circuits with various levels of complexity. A concluding discussion provides some perspectives on possibilities for future work in fundamental and applied aspects.
- 280Battie, Y.; Ducloux, O. Coated and Functionalised Single-Walled Carbon Nanotubes (SWCNTs) as Gas Sensors. In Semiconductor Gas Sensors; Jaaniso, R.; Tan, O. K., Eds.; Woodhead: Oxford, U.K., 2013; pp 356– 385.Google ScholarThere is no corresponding record for this reference.
- 281Sayago, I.; Fernández, M.; Fontecha, J.; Horrillo, M.; Seral-Ascaso, A.; Garriga, R.; Muñoz, E. Carbon Nanotube Networks as Sensitive Layers for Resistive Gas Sensor Applications Nanopages 2013, 8, 15– 26 DOI: 10.1556/Nano.2013.00001Google ScholarThere is no corresponding record for this reference.
- 282Mittal, M.; Kumar, A. Carbon Nanotube (CNT) Gas Sensors for Emissions from Fossil Fuel Burning Sens. Actuators, B 2014, 203, 349– 362 DOI: 10.1016/j.snb.2014.05.080Google Scholar282https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2cXht1Kks7vI&md5=d91f5762353cfec114e8ce9513611229Carbon nanotube (CNT) gas sensors for emissions from fossil fuel burningMittal, M.; Kumar, A.Sensors and Actuators, B: Chemical (2014), 203 (), 349-362CODEN: SABCEB; ISSN:0925-4005. (Elsevier B.V.)A review. Fossil fuels endow wide applications in industrial, transportation, and power generation sectors. However, smoke released by burning fossil fuels contains toxic gases, which pollutes the environment and severely affects human health. Carbon nanotubes (CNTs) are potential material for gas sensors due to their high structural porosity and high sp. surface area. Defects present on the CNT sidewalls and end caps facilitate adsorption of gas mols. The chem. procedures adopted to purify and disperse carbon nanotubes create various chem. groups on their surface, which further enhance the adsorption of gas mols. and thus improve the sensitivity of CNTs. Present review focuses on CNT chemiresistive gas sensing mechanisms, which make them suitable for the development of next generation sensor technol. The resistance of carbon nanotubes decreases when oxidizing gas mols. adsorb on their surface, whereas, adsorption of reducing gas mols. results in increasing the resistance of CNTs. Sensing ability of carbon nanotubes for the gases namely, NO, NO2, CO, CO2 and SO2, released on burning of fossil fuels is reviewed. This review provides basic understanding of sensing mechanisms, creation of adsorption sites by chem. processes and charge transfer between adsorbed gas mols. and surface of CNTs. In addn., useful current update on research and development of CNT gas sensors is provided.
- 283Snow, A. W.; Perkins, F. K.; Ancona, M. G.; Robinson, J. T.; Snow, E. S.; Foos, E. E. Disordered Nanomaterials for Chemielectric Vapor Sensing: A Review IEEE Sens. J. 2015, 15, 1301– 1320 DOI: 10.1109/JSEN.2014.2364677Google Scholar283https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2MXkvV2ktb8%253D&md5=913e64224bfbb9d8ea09a66cec25b7fbDisordered nanomaterials for chemielectric vapor sensing: a reviewSnow, Arthur W.; Perkins, F. Keith; Ancona, Mario G.; Robinson, Jeremy T.; Snow, Eric S.; Foos, Edward E.IEEE Sensors Journal (2015), 15 (3), 1301-1320CODEN: ISJEAZ; ISSN:1530-437X. (Institute of Electrical and Electronics Engineers)Although robust chem. vapor detection by chemielec. point sensors remains as a largely unmet challenge at present, the best performance to date and the most likely avenue for future progress is with sensor designs in which the transductive element is a disordered nanostructured material. We here review the evidence for this claim, with illustrations drawn from recent work on sensors made from gold nanoparticles, carbon nanotubes, and reduced graphene oxide nanoplatelets. These examples can be regarded as being prototypical of disordered nanostructured films formed of primitive objects that are nanoscopic in 3-D, 2-D, and 1-D, resp.
- 284Andersson, M.; Lloyd Spetz, A.; Pearce, R. Recent Trends in Silicon Carbide (SiC) and Graphene-Based Gas Sensors. In Semiconductor Gas Sensors; Jaaniso, R.; Tan, O. K., Eds.; Woodhead: Oxford, U.K., 2013; pp 117– 158.Google ScholarThere is no corresponding record for this reference.
- 285Meng, F. L.; Guo, Z.; Huang, X. J. Graphene-Based Hybrids for Chemiresistive Gas Sensors TrAC, Trends Anal. Chem. 2015, 68, 37– 47 DOI: 10.1016/j.trac.2015.02.008Google Scholar285https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2MXlvVenu7c%253D&md5=572cd8a3e353cadea09022a8f2d06e70Graphene-based hybrids for chemiresistive gas sensorsMeng, Fan-Li; Guo, Zheng; Huang, Xing-JiuTrAC, Trends in Analytical Chemistry (2015), 68 (), 37-47CODEN: TTAEDJ; ISSN:0165-9936. (Elsevier B. V.)Gas sensors can detect combustible, explosive and toxic gases, and have been widely used in safety monitoring and process control in residential buildings, industries and mines. Recently, graphene-based hybrids were widely investigated as chemiresistive gas sensors with high sensitivity and selectivity. This systematic review is therefore timely and necessary to evaluate the success of graphene-based hybrids in gas detection and to identify their challenges. We review the sensing principles and the synthesis process of the graphene-based hybrids with noble metals, metal oxides and conducting polymers to achieve better understanding and design of novel gas sensors. Our review will assist researchers to understand the evolution and the challenges of graphene-based hybrids, and create interest in development of gas-sensing techniques.
- 286Varghese, S. S.; Lonkar, S.; Singh, K. K.; Swaminathan, S.; Abdala, A. Recent Advances in Graphene Based Gas Sensors Sens. Actuators, B 2015, 218, 160– 183 DOI: 10.1016/j.snb.2015.04.062Google Scholar286https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2MXnvFCjs70%253D&md5=85c40ac76209a6814428ee9363134511Recent advances in graphene based gas sensorsVarghese, Seba S.; Lonkar, Sunil; Singh, K. K.; Swaminathan, Sundaram; Abdala, AhmedSensors and Actuators, B: Chemical (2015), 218 (), 160-183CODEN: SABCEB; ISSN:0925-4005. (Elsevier B.V.)Graphene, a single, one-atom-thick sheet of carbon atoms arranged in a honeycomb lattice and the two-dimensional building block for carbon materials, has attracted great interest for a wide range of applications. Due to its superior properties such as thermo-elec. conduction, surface area and mech. strength, graphene materials have inspired huge interest in sensing of various chem. species. In this timely review, we discuss the recent advancement in the field of graphene based gas sensors with emphasis on the use of modified graphene materials. Further, insights of theor. and exptl. aspects assocd. with such systems are also discussed with significance on the sensitivity and selectivity of graphene towards various gas mols. The first section introduces graphene, its synthesis methods and its physico-chem. properties. The second part focuses on the theor. approaches that discuss the structural improvisations of graphene for its effective use as gas sensing materials. The third section discusses the applications of pristine and modified graphene materials in gas sensing applications. Various graphene modification methods are discussed including using dopants and defects, decoration with metal/metal oxide nanoparticles, and functionalization with polymers. Finally, a discussion on the future challenges and perspectives of this enticing field of graphene sensors for gas detection is provided.
- 287Wohltjen, H.; Snow, A. W. Colloidal Metal-Insulator-Metal Ensemble Chemiresistor Sensor Anal. Chem. 1998, 70, 2856– 2859 DOI: 10.1021/ac9713464Google Scholar287https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADyaK1cXjvVKks74%253D&md5=56677240d1c5a23c9e217216fe6e3966Colloidal metal-insulator-metal ensemble chemiresistor sensorWohltjen, Hank; Snow, Arthur W.Analytical Chemistry (1998), 70 (14), 2856-2859CODEN: ANCHAM; ISSN:0003-2700. (American Chemical Society)A colloidal metal-insulator-metal ensemble chemiresistor sensor based on a monolayer stabilized metal nanocluster transducer film is described. In the example presented, the thin transducer film is composed of 2-nm gold clusters encapsulated by octanethiol monolayers and is deposited on an interdigital microelectrode. Responses to org. vapor exposures are large (resistance changes up to 2-fold or more), fast (90% response in <1 s), reversible, and selective. Chemiresistor sorption isotherms for toluene, tetrachloroethylene, 1-propanol, and water vapors are nonlinear and illustrate the high sensitivity and selectivity (ppm detection for toluene and tetrachloroethylene; negligible response for 1-propanol and water).
- 288Chen, S.; Murray, R. W.; Feldberg, S. W. Quantized Capacitance Charging of Monolayer-Protected Au Clusters J. Phys. Chem. B 1998, 102, 9898– 9907 DOI: 10.1021/jp982822cGoogle Scholar288https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADyaK1cXms12isrc%253D&md5=0008dc3f6617e7399a709e9c554a2e01Quantized Capacitance Charging of Monolayer-Protected Au ClustersChen, Shaowei; Murray, Royce W.; Feldberg, Stephen W.Journal of Physical Chemistry B (1998), 102 (49), 9898-9907CODEN: JPCBFK; ISSN:1089-5647. (American Chemical Society)A theor. model based on electrostatic interactions is developed to account for the formal potentials of current peaks obsd. in differential pulse voltammetry of solns. of 10 different nanometer-sized alkylthiolate and arylthiolate monolayer-protected Au clusters. The current peaks arise from successive, quantized (single-electron) capacitative charging of ensembles of individual cluster cores (i.e., electrochem. ensemble Coulomb staircase charging). Exptl. peak potentials for a given cluster change roughly linearly with changes in its core charge state, as predicted by the theory, and the sub-attofarad capacitances (CCLU) of individual clusters obtained from the slopes of such plots agree with those estd. from a simple concentric sphere capacitor model. The charging of clusters with very small cores becomes redox mol.-like, indicating as reported recently, the emergence of HOMO-LUMO energy gaps. Because the quantized charging currents of the clusters are diffusion controlled, their voltammetric behavior can be readily simulated, but requires attention to dispersities in CCLU that occur in exptl. samples of these materials. Simulations of microelectrode voltammetry incorporating Gaussian dispersions in cluster properties display features similar to those obsd. exptl. The simulations show that quantized charging features are more difficult to detect when the nanoparticles are not monodisperse, but can be seen in polydisperse samples when the cores are small (small CCLU) and not highly charged.
- 289Wang, L.; Shi, X.; Kariuki, N. N.; Schadt, M.; Wang, G. R.; Rendeng, Q.; Choi, J.; Luo, J.; Lu, S.; Zhong, C.-J. Array of Molecularly Mediated Thin Film Assemblies of Nanoparticles: Correlation of Vapor Sensing with Interparticle Spatial Properties J. Am. Chem. Soc. 2007, 129, 2161– 2170 DOI: 10.1021/ja0673074Google Scholar289https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD2sXot1ahsw%253D%253D&md5=7822d5b0d86b4fadacb8b857ffdd0618Array of molecularly mediated thin film assemblies of nanoparticles: Correlation of vapor sensing with interparticle spatial propertiesWang, Lingyan; Shi, Xiajing; Kariuki, Nancy N.; Schadt, Mark; Wang, Guannan Roger; Rendeng, Qiang; Choi, Jeongku; Luo, Jin; Lu, Susan; Zhong, Chuan-JianJournal of the American Chemical Society (2007), 129 (7), 2161-2170CODEN: JACSAT; ISSN:0002-7863. (American Chemical Society)The ability to tune interparticle spatial properties of nanoparticle assemblies is essential for the design of sensing materials toward desired sensitivity and selectivity. This paper reports findings of a study of molecularly mediated thin film assemblies of metal nanoparticles with controllable interparticle spatial properties as a sensing array. The interparticle spatial properties are controlled by a combination of α,ω-difunctional alkyl mediators (X-(CH2)n-X) such as alkyl dithiols, dicarboxylic acid acids, and alkanethiol shells capped on nanoparticles. Alkanethiolate-capped gold and gold-silver alloy nanoparticles (2-3 nm) were studied as model building blocks toward the thin film assemblies, whereas the variation of alkyl chain length manipulates the interparticle spacing. The thin films assembled on an interdigitated microelectrode array platform were characterized for detg. their responses to the sorption of volatile org. compds. (VOCs). The correlation between the response sensitivity and the interparticle spacing properties revealed not only a clear dependence of the sensitivity on alkyl chain length but also the occurrence of a dramatic change of the sensitivity in a region of chain length for the alkyl mediator comparable with that of the capping alkyl chains. This finding reflects a balance between the interparticle chain-chain cohesive interdigitation and the nanostructure-vapor interaction which dets. the relative change of the elec. cond. of the inked nanoparticle thin film in response to vapor sorption. The results, along with statistical anal. of the sensor array data in terms of sensitivity and selectivity, provided important insights into the detailed delineation between the interparticle spacing and the nanostructured sensing properties.
- 290Joseph, Y.; Guse, B.; Yasuda, A.; Vossmeyer, T. Chemiresistor Coatings from Pt- and Au-Nanoparticle/Nonanedithiol Films: Sensitivity to Gases and Solvent Vapors Sens. Actuators, B 2004, 98, 188– 195 DOI: 10.1016/j.snb.2003.10.006Google Scholar290https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD2cXhs12hsrg%253D&md5=fadf23b174635db00ee706e87eed7fc6Chemiresistor coatings from Pt- and Au-nanoparticle/nonanedithiol films: sensitivity to gases and solvent vaporsJoseph, Yvonne; Guse, Berit; Yasuda, Akio; Vossmeyer, TobiasSensors and Actuators, B: Chemical (2004), 98 (2-3), 188-195CODEN: SABCEB; ISSN:0925-4005. (Elsevier Science B.V.)Chemiresistor coatings are fabricated via layer-by-layer self-assembly using 1,9-nonanedithiol (NT) and dodecylamine-stabilized Pt- or Au-nanoparticles. The film thickness, as detd. by at. force microscopy (AFM), is 66 ± 2 and 31 ± 1 nm, resp. These film materials show linear current-voltage characteristics and conductivities in the range of ∼10-3 and ∼10-4 Ω-1 cm-1 at room temp. The sensitivity of the films was studied by dosing them with the gases ammonia (NH3), carbon monoxide (CO) and vapors of water and toluene in the concn. range from 300 ppb to 5000 ppm. To all analytes the films respond with an increase of their resistance. Although the total signal intensities are rather weak, these sensors show a very high signal-to-noise ratio, which enables a detection limit for NH3 <100 ppb. The response dynamics and the curvature of the response isotherms indicate that NH3 and CO bind significantly stronger to the film material than water or toluene. This result is interpreted with the assumption that NH3 and CO bind to vacant sites on the metal nanoparticle cores, whereas water and toluene interact preferably with the NT linker mols.
- 291Wang, L.; Luo, J.; Yin, J.; Zhang, H.; Wu, J.; Shi, X.; Crew, E.; Xu, Z.; Rendeng, Q.; Lu, S.; Poliks, M.; Sammakia, B.; Zhong, C.-J. Flexible Chemiresistor Sensors: Thin Film Assemblies of Nanoparticles on a Polyethylene Terephthalate Substrate J. Mater. Chem. 2010, 20, 907– 915 DOI: 10.1039/B920957CGoogle ScholarThere is no corresponding record for this reference.
- 292Evans, S. D.; Johnson, S. R.; Cheng, Y. L.; Shen, T. Vapour Sensing Using Hybrid Organic-Inorganic Nanostructured Materials J. Mater. Chem. 2000, 10, 183– 188 DOI: 10.1039/a903951aGoogle Scholar292https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADyaK1MXotVKgu7Y%253D&md5=2d70376fbd43ac310ac4602df828f2b0Vapour sensing using hybrid organic-inorganic nanostructured materialsEvans, Stephen D.; Johnson, Simon R.; Cheng, Yaling L.; Shen, TiehanJournal of Materials Chemistry (2000), 10 (1), 183-188CODEN: JMACEP; ISSN:0959-9428. (Royal Society of Chemistry)Small arom. organothiol derivs., with the structure HS-C6H4-X, were used to stabilize gold nanoparticles. The nature of the functional group, X, is important for controlling the relative strength of the particle-particle and particle-solvent interactions and hence in detg. the phys. properties of these systems (e.g. soly.). Particles were stabilized with different ligands for which X = OH, -COOH, -NH2, -Me and thin films of the particles were formed, by soln. evapn., on microelectrode patterned surfaces. The electronic behavior indicates that conduction can be understood in terms of an activated electron tunnelling model. Finally, preliminary studies were carried out on the effect of exposure to different chem. vapors on the electronic transport properties.
- 293Yang, C.-Y.; Li, C.-L.; Lu, C.-J. A Vapor Selectivity Study of Microsensor Arrays Employing Various Functionalized Ligand Protected Gold Nanoclusters Anal. Chim. Acta 2006, 565, 17– 26 DOI: 10.1016/j.aca.2006.02.005Google Scholar293https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD28XjslCmu7w%253D&md5=bf1f6a968404d44f73ed8d2c215c5ef9A vapor selectivity study of microsensor arrays employing various functionalized ligand protected gold nanoclustersYang, Chang-Yong; Li, Chi-Lin; Lu, Chia-JungAnalytica Chimica Acta (2006), 565 (1), 17-26CODEN: ACACAM; ISSN:0003-2670. (Elsevier B.V.)The authors synthesized and tested four different monolayer protected gold nanoclusters (MPCs) as chem. selective interfaces for an org. vapor sensor array. The ligands chosen for capping the nano-Au particles and for selective org. vapor sorption were octanethiol, 2-naphthalenethiol, 2-benzothiazolethiol and 4-methoxythiolphenol. The same set of gold nanoclusters were tested on two different types of sensor platforms, a chemiresistor (CR) and a quartz crystal microbalance (QCM). The sensing properties of both sensor arrays were studied with 10 org. vapors of various functional groups. Vapor sensing selectivity, dominated by the shell ligand structure of MPC, was demonstrated. The sensitivities of MPC coated CR are better than those of QCM sensors coated with the same material. The av. CR/QCM amplification factors are range from 1.9 for 4-methoxythiolphenol MPC to 16.9 for octanethiol MPC. These differences in amplification factors indicate the functional group specific mechanisms for each vapor-MPC pair. The shell penetration mechanism of hydrogen-bonding vapor mols. into the 2-benzothiazolethiol capped MPC reduced the CR/QCM amplification factors. Strong attraction between MPC shell ligands can also reduce the magnitude of resistance changes during vapor sorption.
- 294Ibañez, F. J.; Zamborini, F. P. Chemiresistive Sensing of Volatile Organic Compounds with Films of Surfactant-Stabilized Gold and Gold-Silver Alloy Nanoparticles ACS Nano 2008, 2, 1543– 1552 DOI: 10.1021/nn800109qGoogle Scholar294https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD1cXovVGmtbs%253D&md5=f0fa065de65213eb548e58310fbde774Chemiresistive sensing of volatile organic compounds with films of surfactant-stabilized gold and gold-silver alloy nanoparticlesIbanez, Francisco J.; Zamborini, Francis P.ACS Nano (2008), 2 (8), 1543-1552CODEN: ANCAC3; ISSN:1936-0851. (American Chemical Society)The authors describe the chemiresistive sensing of volatile org. compds. (VOCs) with films of chem. synthesized ∼4 nm diam. Au and AuAg alloy nanoparticles (NPs) stabilized by a surfactant, tetraoctylammonium bromide (TOABr). The chemiresistive sensing properties were measured over a concn. range of 100 to 0.04% satn. for methanol (MeOH), ethanol (EtOH), 2-propanol (IPA), and toluene (Tol) vapor analytes and compared directly to the chemiresistive sensing properties of films of 1.6 nm diam. hexanethiolate (C6S)-coated Au monolayer-protected clusters (MPCs). Films of TOABr-stabilized Au NPs exhibit the opposite response compared to those of C6S-coated Au MPCs. The details are unclear, but the mechanism likely involves changes in capacitive charging in the film or improved conductive pathways through the Au NPs upon incorporation of VOCs into the film for the former as opposed to the known change in electron hopping cond. for the latter. This decreases resistance in the presence of VOCs for TOABr Au as opposed to an increase for C6S Au. The TOABr Au sensors are more sensitive, esp. for polar analytes, and have greater long-term stability compared to C6S Au. The limit of detection (LOD) for films of TOABr-coated Au NPs is 3, 2, 12, and 37 ppm for IPA, MeOH, EtOH, and Tol, resp., as compared to 106, 326, 242, and 48 for C6S Au. Films of TOABr-stabilized AuAg alloy NPs exhibit the same type of response, but the sensitivity decreases dramatically with increasing Ag content, showing that the metal compn. of the NPs in the film plays a role in the sensing properties, which was not well-recognized in the literature.
- 295Joseph, Y.; Guse, B.; Nelles, G. Aging of 1,ω-Alkyldithiol Interlinked Au Nanoparticle Networks Chem. Mater. 2009, 21, 1670– 1676 DOI: 10.1021/cm803407nGoogle Scholar295https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD1MXjsFemt7Y%253D&md5=1d44b1d01319796ab708cf0ec52730dcAging of 1,ω-Alkyldithiol Interlinked Au Nanoparticle NetworksJoseph, Yvonne; Guse, Berit; Nelles, GabrieleChemistry of Materials (2009), 21 (8), 1670-1676CODEN: CMATEX; ISSN:0897-4756. (American Chemical Society)To identify the aging processes during long-term storage under different storage conditions, the authors studied the compn. of films comprising gold nanoparticles interlinked with 1,9-nonanedithiol and 1,16-hexadecanedithiol during a 44 mo period using XPS. Addnl., the authors compared the initial structure and sensing properties toward toluene, 1-propanol, water, and hydrogen sulfide with the morphol. and sensitivity after storage. Films stored under ambient conditions showed oxidn. of sulfur and carbon and appearance of nitrogen, a significant loss of sulfur and the formation of larger particles in the film. The chem. selectivity of these films changed toward hydrophilic vapors and they became sensitive toward hydrogen sulfide. This is explained by the reaction of the thiol groups with ozone from the air, which destabilizes the network and significantly influences the particle/org. interface acting as sorption sites for gases. For films stored under argon only, an increase in free thiol groups in conjunction with a structural rearrangement of the film was obsd. The selectivity of these films changed slightly toward hydrophilic analytes but they were still insensitive toward hydrogen sulfide.
- 296Krasteva, N.; Guse, B.; Besnard, I.; Yasuda, A.; Vossmeyer, T. Gold Nanoparticle/PPI-Dendrimer Based Chemiresistors - Vapor-Sensing Properties as a Function of the Dendrimer Size Sens. Actuators, B 2003, 92, 137– 143 DOI: 10.1016/S0925-4005(03)00250-8Google Scholar296https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD3sXjs1Cnsrg%253D&md5=9f21af5d594de996b635df717a5592bdGold nanoparticle/PPI-dendrimer based chemiresistors. Vapor-sensing properties as a function of the dendrimer sizeKrasteva, Nadejda; Guse, Berit; Besnard, Isabelle; Yasuda, Akio; Vossmeyer, TobiasSensors and Actuators, B: Chemical (2003), B92 (1-2), 137-143CODEN: SABCEB; ISSN:0925-4005. (Elsevier Science B.V.)Gold nanoparticle/poly(propyleneimine) (PPI) composite films comprising dendrimers of generation one to five were prepd. via layer-by-layer self-assembly. The thickness of the films is detd. by at. force microscopy and ranges between 19 and 32 nm. Field-emission SEM (FE-SEM) images show that the bulk of the films consist of nanoparticles with a diam. of ∼4 nm. Current-voltage measurements were used to characterize the elec. properties of the films. The resistivity of the films depends strongly on the size of the dendrimers and increases exponentially with increasing dendrimer generation. This result is discussed in terms of an activated tunneling model for charge transport. The chem. sensitivity of the films is probed by dosing them with vapors of toluene, 1-propanol, and water in a concn. range between 100 and 5000 ppm. All vapors cause an increase of the films' resistances. While the sensitivity to toluene and 1-propanol increases significantly with increasing dendrimer generation, the sensitivity to water is rather independent of the dendrimer size. This behavior is qual. explained by different sorption sites for the different classes of analytes used.
- 297Krasteva, N.; Fogel, Y.; Bauer, R. E.; Müllen, K.; Joseph, Y.; Matsuzawa, N.; Yasuda, A.; Vossmeyer, T. Vapor Sorption and Electrical Response of Au-Nanoparticle-Dendrimer Composites Adv. Funct. Mater. 2007, 17, 881– 888 DOI: 10.1002/adfm.200600598Google ScholarThere is no corresponding record for this reference.
- 298Joseph, Y.; Peic, A.; Chen, X.; Michl, J.; Vossmeyer, T.; Yasuda, A. Vapor Sensitivity of Networked Gold Nanoparticle Chemiresistors: Importance of Flexibility and Resistivity of the Interlinkage J. Phys. Chem. C 2007, 111, 12855– 12859 DOI: 10.1021/jp072053+Google Scholar298https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD2sXos1Srsr0%253D&md5=1ace256278c1c051567fd9bdf7bbe468Vapor sensitivity of networked gold nanoparticle chemiresistors: Importance of flexibility and resistivity of the interlinkageJoseph, Yvonne; Peic, Antun; Chen, Xudong; Michl, Josef; Vossmeyer, Tobias; Yasuda, AkioJournal of Physical Chemistry C (2007), 111 (34), 12855-12859CODEN: JPCCCK; ISSN:1932-7447. (American Chemical Society)The authors studied the response behavior of chemiresistors made from differently interlinked networks of gold nanoparticles. The authors' results show that the degree of flexibility and cond. of the interlinkage between the nanoparticles has a profound impact on the response characteristics of such sensors. 1,12-Dodecanedithiol was used as a hydrophobic, flexible linker compd. For comparison, [4]-staffane-3,3'''-dithiol provided a rigid, rodlike linkage, and 4,4'-terphenyldithiol was used as a rigid linker with enhanced cond. due to its delocalized arom. moieties. As detd. by AFM, all three sensor coatings had similar thicknesses (∼30 nm), but the degree of interlinkage, as measured by XPS, was significantly higher in the case of the flexible network. All three materials showed linear current-voltage characteristics. The vapor sensitivity was tested by dosing the sensors with toluene, 1-propanol, 4-methyl-2-pentanone, and water in the concn. range 100-5000 ppm at 0% relative humidity. The flexible 1,12-dodecanedithiol interlinked film responded with an increase in resistance to these analytes and with the highest sensitivity to toluene. In striking contrast, the rigid staffane interlinked film responded with a decrease in resistance to all four analytes and with the highest sensitivity to 4-methyl-2-pentanone. The rigid but more conductive 4,4'-terphenyldithiol interlinked coating gave hardly any response, although microgravimetric measurements showed that similar amts. of analytes were absorbed as in the case of the other two sensor films. The different response characteristics are discussed in terms of film swelling and changes in permittivity.
- 299Franke, M. E.; Koplin, T. J.; Simon, U. Metal and Metal Oxide Nanoparticles in Chemiresistors: Does the Nanoscale Matter? Small 2006, 2, 36– 50 DOI: 10.1002/smll.200500261Google Scholar299https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD2MXhtlWqsrvN&md5=6d56e84616cdc75205ce6d595bafaf5aMetal and metal oxide nanoparticles in chemiresistors: Does the nanoscale matter?Franke, Marion E.; Koplin, Tobias J.; Simon, UlrichSmall (2006), 2 (1), 36-50CODEN: SMALBC; ISSN:1613-6810. (Wiley-VCH Verlag GmbH & Co. KGaA)A review. Sensor technol. is one of the most important key technologies of the future with a constantly increasing no. of applications, both in the industrial and in the private sectors. More and more gas sensors were used for the control of tech. processes, in environment monitoring, healthcare, and automobiles. Consequently, the development of fast and sensitive gas sensors with small cross sensitivity is the subject of intense research, propelled by strategies based on nanoscience and technol. Established systems can be improved and novel sensor concepts based on bottom-up approaches show that the sensor properties can be controlled by mol. design. This review highlights the recent developments and reflects the impact of nanoscience on sensor technol.
- 300Drake, C.; Deshpande, S.; Bera, D.; Seal, S. Metallic Nanostructured Materials Based Sensors Int. Mater. Rev. 2007, 52, 289– 316 DOI: 10.1179/174328007X212481Google Scholar300https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD2sXht1WksbvK&md5=0f9301e297f19d0cb786cb3a0bc07c42Metallic nanostructured materials based sensorsDrake, C.; Deshpande, S.; Bera, D.; Seal, S.International Materials Reviews (2007), 52 (5), 289-317CODEN: INMREO; ISSN:0950-6608. (Maney Publishing)A review. In recent years, a significant interest has developed on metallic nanostructures based sensors for the detection of gas, volatile org. compds. (VOCs), and biomols. in the wake of counter-terrorism threats and environmental pollution. Enhancement in selectivity and overall efficiency of the sensors is achieved by tailoring size, structure and shape of the nanoparticles. In the last decade, numerous studies revealed various sensing properties of these nanomaterials. However, improvements in overall sensor performance such as sensitivity, selectivity, response time, recovery time and robustness demand further improvement. This warrants a proper understanding of the basic principles behind the sensing properties of metallic nanostructures. In this review, principles of few important sensing systems, their sensing mechanisms, merits and demerits along with some of the applications on the detection of gas, VOC and biol. mols. are discussed. This review also highlights the importance of using metal nanostructures in various sensor systems. Although the development of nanotechnol. provides new avenue to sensor research, there exist several unexplored territories for the application of nanostructured materials onto the device. This review encompasses some significant efforts on the application of nanomaterials in the various sensing systems.
- 301Zabet-Khosousi, A.; Dhirani, A.-A. Charge Transport in Nanoparticle Assemblies Chem. Rev. 2008, 108, 4072– 4124 DOI: 10.1021/cr0680134Google Scholar301https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD1cXhtFGjs7nK&md5=536921ef348c94af0d8a3eaa05b8372fCharge Transport in Nanoparticle AssembliesZabet-Khosousi, Amir; Dhirani, Al-AminChemical Reviews (Washington, DC, United States) (2008), 108 (10), 4072-4124CODEN: CHREAY; ISSN:0009-2665. (American Chemical Society)A review. Nanoparticle assemblies exhibit bulk properties that are controllable from the bottom up. Nanoparticles with a variety of optical, chem., and electronic functionalities can be prepd. by chem. synthetic methods. Mols.-either as capping ligands or crosslinkers-can confer addnl. functionalities control inter-nanoparticle sepns., and influence the rate of charge transfer between nanoparticles. Properties of assemblies can be further controlled via assembly procedure. Assemblies can be organized into 1D, 2D, and 3D arrays of various length scales with controllable degrees of order/disorder. They can exhibit unusual architectural features such as large porosity and surface area that can be desirable depending on application. The controlled functionality afforded by nanoparticle assemblies combined with the ability of nanoparticles to serve as charge relays has enabled a host of new opportunities, both fundamental and applied. Assemblies have enabled systematic studies of phenomena ranging from single-electron charging to metal-insulator transitions. In terms of applications, there has been particular interest in exploiting functionality of nanoparticle assemblies for electronic chem. and biol. sensing. A no. of proof-of-principle devices, such as vapor-, electrochem.-, chem.-, and biosensors, have already been demonstrated. Further studies are required to explore more fully the large range of material properties and applications enabled by the large choice of assembly components and architectures. In view of the desirable features of electronics this area will likely continue to represent a significant target of opportunity for future studies.
- 302Wanekaya, A. K.; Uematsu, M.; Breimer, M.; Sadik, O. A. Multicomponent Analysis of Alcohol Vapors Using Integrated Gas Chromatography with Sensor Arrays Sens. Actuators, B 2005, 110, 41– 48 DOI: 10.1016/j.snb.2005.01.025Google Scholar302https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD2MXmvFOqsrk%253D&md5=c84496e1d4026640c435980ec7a26273Multicomponent analysis of alcohol vapors using integrated gas chromatography with sensor arraysWanekaya, Adam K.; Uematsu, Michiko; Breimer, Marc; Sadik, Omowunmi A.Sensors and Actuators, B: Chemical (2005), 110 (1), 41-48CODEN: SABCEB; ISSN:0925-4005. (Elsevier B.V.)The authors have fabricated and tested a multiarray polymer sensor by integrating the sensor array with a gas chromatograph. The authors compared the performance of the system with a contemporary thermocond. detector for the identification and detection of different volatile org. compds. (VOCs). These sensor arrays were not only able to detect the different compds. but also demonstrated a very wide linear response to the amts. of VOC exposure. The performance of the gas chromatograph-polymer sensor array detector (GC-PSAD) was very good and comparable to the gas chromatograph thermal cond. detector (GC-TCD) system in terms of linearity and reproducibility. The repeatability of peak heights and areas was consistent over several months. The PSAD chip is easily fabricated and that process including the polymer deposition is described. The authors' exptl. results suggest that the GC-PSAD system is effective in the anal. of mixts. and this is a distinct advantage over the contemporary electronic nose sensor array systems.
- 303Grate, J. W.; Abraham, M. H. Solubility Interactions and the Design of Chemically Selective Sorbent Coatings for Chemical Sensors and Arrays Sens. Actuators, B 1991, 3, 85– 111 DOI: 10.1016/0925-4005(91)80202-UGoogle ScholarThere is no corresponding record for this reference.
- 304Abraham, M. H. Scales of Solute Hydrogen Bonding: Their Construction and Application to Physicochemical and Biochemical Processes Chem. Soc. Rev. 1993, 22, 73– 83 DOI: 10.1039/cs9932200073Google ScholarThere is no corresponding record for this reference.
- 305Grate, J. W.; Wise, B. M.; Abraham, M. H. Method for Unknown Vapor Characterization and Classification Using a Multivariate Sorption Detector. Initial Derivation and Modeling Based on Polymer-Coated Acoustic Wave Sensor Arrays and Linear Solvation Energy Relationships Anal. Chem. 1999, 71, 4544– 4553 DOI: 10.1021/ac990336vGoogle ScholarThere is no corresponding record for this reference.
- 306Hierlemann, A.; Zellers, E. T.; Ricco, A. J. Use of Linear Solvation Energy Relationships for Modeling Responses from Polymer-Coated Acoustic-Wave Vapor Sensors Anal. Chem. 2001, 73, 3458– 3466 DOI: 10.1021/ac010083hGoogle Scholar306https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD3MXktVyksrc%253D&md5=b45b0a71a1820080a3402bccc4fbf33aUse of Linear Solvation Energy Relationships for Modeling Responses from Polymer-Coated Acoustic-Wave Vapor SensorsHierlemann, Andreas; Zellers, Edward T.; Ricco, Antonio J.Analytical Chemistry (2001), 73 (14), 3458-3466CODEN: ANCHAM; ISSN:0003-2700. (American Chemical Society)The applicability and performance of linear solvation energy relations (LSERs) as models of responses from polymer-coated acoustic-wave vapor sensors are critically examd. Criteria for the use of these thermodn. models with thickness-shear-mode resonator (TSMR) and surface-acoustic-wave (SAW) vapor sensors are clarified. Published partition coeff. values derived from gas-liq. chromatog. (GLC) are consistently lower than those obtained gravimetrically, in accordance with previous reports, suggesting that LSERs based on GLC-derived partition coeffs. will not provide accurate ests. of acoustic-wave sensor responses. The development of LSER models directly from polymer-coated TSMR vapor sensor response data is demonstrated and a revised model developed from SAW vapor sensor response data, which takes account of viscoelastic changes in polymeric coating films, is presented and compared to those developed by other methods.
- 307Verma, P.; Yadava, R. D. S. A Data Mining Procedure for Polymer Selection for Making Surface Acoustic Wave Sensor Array Sens. Lett. 2013, 11, 1903– 1918 DOI: 10.1166/sl.2013.3047Google ScholarThere is no corresponding record for this reference.
- 308Grate, J. W.; Abraham, M. H.; Du, C. M.; McGill, R. A.; Shuely, W. J. Examination of Vapor Sorption by Fullerene, Fullerene-Coated Surface Acoustic Wave Sensors, Graphite, and Low-Polarity Polymers Using Linear Solvation Energy Relationships Langmuir 1995, 11, 2125– 2130 DOI: 10.1021/la00006a046Google ScholarThere is no corresponding record for this reference.
- 309Li, C.-L.; Lu, C.-J. Establishing Linear Solvation Energy Relationships between Vocs and Monolayer-Protected Gold Nanoclusters Using Quartz Crystal Microbalance Talanta 2009, 79, 851– 855 DOI: 10.1016/j.talanta.2009.05.012Google ScholarThere is no corresponding record for this reference.
- 310Abraham, M. H.; Andonian-Haftvan, J.; Whiting, G. S.; Leo, A.; Taft, R. S. Hydrogen Bonding. Part 34. The Factors That Influence the Solubility of Gases and Vapours in Water at 298 K, and a New Method for Its Determination J. Chem. Soc., Perkin Trans. 2 1994, 2, 1777– 1791 DOI: 10.1039/p29940001777Google ScholarThere is no corresponding record for this reference.
- 311Kummer, A. M.; Hierlemann, A.; Baltes, H. Tuning Sensitivity and Selectivity of Complementary Metal Oxide Semiconductor-Based Capacitive Chemical Microsensors Anal. Chem. 2004, 76, 2470– 2477 DOI: 10.1021/ac0352272Google Scholar311https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD2cXisVyisr8%253D&md5=0fe903614ab15426ceacebe83701f6a0Tuning Sensitivity and Selectivity of Complementary Metal Oxide Semiconductor-Based Capacitive Chemical MicrosensorsKummer, Adrian M.; Hierlemann, Andreas; Baltes, HenryAnalytical Chemistry (2004), 76 (9), 2470-2477CODEN: ANCHAM; ISSN:0003-2700. (American Chemical Society)New details on selectivity and sensitivity of fully integrated CMOS-based capacitive chem. microsensor systems are revealed. These microsystems were developed to detect volatile orgs. in ambient air and rely on polymeric sensitive layers. The sensitivity and selectivity changes induced by thickness variation of the sensitive polymer layer allow for tuning of the layer parameters to achieve desired sensor features. Cross-sensitivity to interfering agents can be drastically reduced, as is shown for two important cases: (a) rendering the capacitive sensor insensitive to a low-dielec.-const. analyte (lower than that of the polymer) and (b) reducing the influence of a high-dielec.-const. analyte, such as H2O, on the sensor response. The 2nd case is of vital importance for capacitive sensors, since H2O is omnipresent and evokes large capacitive sensor signals. The thickness-induced selectivity is explained as a combination of dielec. const. change and swelling and was confirmed by measurements. Exptl. detd. sensitivities qual. and quant. coincide with the calcd. values implying understanding of the sensing mechanism.
- 312Potyrailo, R. A.; Sexton, D. W.; Go, S. Y. Sensing System and Method. U.S. Patent Appl. 20160187277, 2016.Google ScholarThere is no corresponding record for this reference.
- 313Wali, R. P.; Wilkinson, P. R.; Eaimkhong, S. P.; Hernando-Garcia, J.; Sánchez-Rojas, J. L.; Ababneh, A.; Gimzewski, J. K. Fourier Transform Mechanical Spectroscopy of Micro-Fabricated Electromechanical Resonators: A Novel, Information-Rich Pulse Method for Sensor Applications Sens. Actuators, B 2010, 147, 508– 516 DOI: 10.1016/j.snb.2010.03.086Google ScholarThere is no corresponding record for this reference.
- 314Regmi, B. P.; Monk, J.; El-Zahab, B.; Das, S.; Hung, F. R.; Hayes, D. J.; Warner, I. M. A Novel Composite Film for Detection and Molecular Weight Determination of Organic Vapors J. Mater. Chem. 2012, 22, 13732– 13741 DOI: 10.1039/c2jm31623dGoogle Scholar314https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC38XoslGgsL0%253D&md5=fc972fadf6a469a82672858f2c7b7262A novel composite film for detection and molecular weight determination of organic vaporsRegmi, Bishnu P.; Monk, Joshua; El-Zahab, Bilal; Das, Susmita; Hung, Francisco R.; Hayes, Daniel J.; Warner, Isiah M.Journal of Materials Chemistry (2012), 22 (27), 13732-13741CODEN: JMACEP; ISSN:0959-9428. (Royal Society of Chemistry)A novel vapor-sensitive composite film comprising cellulose acetate and a representative compd. (1-n-butyl-2,3-dimethylimidazolium hexafluorophosphate) from a Group of Uniform Materials Based on Org. Salts (GUMBOS) was developed and characterized. The vapor sensing characteristics of the film was studied using a quartz crystal microbalance (QCM) transducer. The material exhibited greatly improved performance characteristics toward a no. of org. vapors. The ratio of the change in resonance frequency (Δf) to the change in motional resistance (ΔR) is a concn.-independent quantity proportional to the mol. wt. of the absorbed chem. species. To the best of the authors' knowledge, this is the 1st study to show a direct relation between Δf/ΔR and the mol. wt. of analytes. This unique finding should prove extremely useful for easy identification and mol. wt. detn. of a broad range of chem. vapors.
- 315Bachar, N.; Liberman, L.; Muallem, F.; Feng, X.; Müllen, K.; Haick, H. Sensor Arrays Based on Polycyclic Aromatic Hydrocarbons: Chemiresistors Versus Quartz-Crystal Microbalance ACS Appl. Mater. Interfaces 2013, 5, 11641– 11653 DOI: 10.1021/am403067tGoogle Scholar315https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC3sXhs1Gqu7bK&md5=c914d9429fc49904990db78d227c6124Sensor Arrays Based on Polycyclic Aromatic Hydrocarbons: Chemiresistors versus Quartz-Crystal MicrobalanceBachar, Nadav; Liberman, Lucy; Muallem, Fairouz; Feng, Xinliang; Mullen, Klaus; Haick, HossamACS Applied Materials & Interfaces (2013), 5 (22), 11641-11653CODEN: AAMICK; ISSN:1944-8244. (American Chemical Society)Arrays of broadly cross-reactive sensors are key elements of smart, self-training sensing systems. Chem. sensitive resistors and quartz-crystal microbalance (QCM) sensors are attractive for sensing applications that involve detection and classification of volatile org. compds. (VOCs) in the gas phase. Polycyclic arom. hydrocarbon (PAH) derivs. as sensing materials can provide good sensitivity and robust selectivity towards different polar and nonpolar VOCs, while being quite tolerant to large humidity variations. Here, the authors present a comparative study of chemiresistor and QCM arrays based on a set of custom-designed PAH derivs. having either purely nonpolar coronas or alternating nonpolar and strongly polar side chain termination. The arrays were exposed to various concns. of representative polar and nonpolar VOCs under extremely varying humidity conditions (5-80% RH). The sensor arrays' classification ability of VOC polarity, chem. class and compd. sepn. was explained in terms of the sensing characteristics of the constituent sensors and their interaction with the VOCs. The results presented here contribute to the development of novel versatile and cost-effective real-world VOC sensing platforms.
- 316Yun, M.; Lee, S.; Yim, C.; Jung, N.; Thundat, T.; Jeon, S. Suspended Polymer Nanobridge on a Quartz Resonator Appl. Phys. Lett. 2013, 103, 053109 DOI: 10.1063/1.4817259Google ScholarThere is no corresponding record for this reference.
- 317Lee, S.; Yun, M.; Jeon, S. A Tunable Microresonator Sensor Based on a Photocrosslinking Polymer Microwire Appl. Phys. Lett. 2014, 104, 053506 DOI: 10.1063/1.4864272Google ScholarThere is no corresponding record for this reference.
- 318Sampson, S. A.; Date, K. S.; Panchal, S. V.; Ambrale, A.; Datar, S. S. Investigation of QTF Based Gas Sensors Sens. Actuators, B 2015, 216, 586– 594 DOI: 10.1016/j.snb.2015.04.024Google Scholar318https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2MXntlCqs7c%253D&md5=75c0c09c235f8e751cf24174d070e722Investigation of QTF based gas sensorsSampson, S. Abraham; Date, Kalyani S.; Panchal, Suresh Vaijnath; Ambrale, Ajit; Datar, Suwarna S.Sensors and Actuators, B: Chemical (2015), 216 (), 586-594CODEN: SABCEB; ISSN:0925-4005. (Elsevier B.V.)Here we investigate the feasibility of using quartz tuning forks (QTFs) modified with nanostructure decorated polymer wires as potential gas sensors. The sensing parameters of different sensors for various volatile org. compds. like ethanol, methanol, chloroform and acetone were investigated. The exposure of the functionalized QTF sensors to VOC vapors induces a change in the mass as well as the mech. properties of the polymer wire due to which the resonant frequency of the system changes. The dependence of the general behavior and the frequency response of the sensors on both mass loading and spring loading effect was investigated and verified exptl.
- 319Holloway, A. F.; Nabok, A.; Thompson, M.; Ray, A. K.; Wilkop, T. Impedance Analysis of the Thickness Shear Mode Resonator for Organic Vapour Sensing Sens. Actuators, B 2004, 99, 355– 360 DOI: 10.1016/j.snb.2003.12.002Google Scholar319https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD2cXjs1Cmtbg%253D&md5=386d11403ac7c00786aeb4e4a05453faImpedance analysis of the thickness shear mode resonator for organic vapour sensingHolloway, A. F.; Nabok, A.; Thompson, M.; Ray, A. K.; Wilkop, T.Sensors and Actuators, B: Chemical (2004), B99 (2-3), 355-360CODEN: SABCEB; ISSN:0925-4005. (Elsevier Science B.V.)The impedance anal. of thickness shear mode (TSM) resonator coated with calixarene films was successfully exploited for the registration of org. solvent vapors of relatively high (pre-explosive) concns. The impedance anal. consisted of fitting the exptl. admittance spectra of TSM resonators to the equiv. circuit model using a highly accurate and reliable least squares algorithm. This approach allowed simultaneous monitoring of the changes in mass and viscoelastic properties of the sensitive membrane caused by adsorption of org. vapors and therefore enables both quantification and discrimination between the vapors of different types of org. solvents, such as hexane and toluene.
- 320Mihara, T.; Ikehara, T.; Konno, M.; Murakami, S.; Maeda, R.; Fukawa, T.; Kimura, M. Design, Fabrication, and Evaluation of Highly Sensitive Compact Chemical Sensor System Employing a Microcantilever Array and a Preconcentrator Sens. Mater. 2011, 23, 397– 417Google Scholar320https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC3MXhsFGlsL7L&md5=7ed0e7aa4f2182d7716fc36da57f8c46Design, fabrication, and evaluation of highly sensitive compact chemical sensor system employing a microcantilever array and a preconcentratorMihara, Takashi; Ikehara, Tsuyoshi; Konno, Mitsuo; Murakami, Sunao; Maeda, Ryutaro; Fukawa, Tadashi; Kimura, MutsumiSensors and Materials (2011), 23 (7), 397-417CODEN: SENMER; ISSN:0914-4935. (Scientific Publishing Division of MYU K.K.)A highly sensitive compact chem. sensor system is developed employing a polymer-coated microcantilever sensor array and a thermal preconcentrator. The design, structure, fabrication, and expt. results are reported here. This sensor system had a sub-ppb detection limit concd. by a preconcentrator and anal. function by thermal desorption of the preconcentrator and multiple cantilevers (acting as the mass sensor) with different polymers. The preconcentrator contained 0.03 g of carbon fiber, and absorption/desorption were controlled by the temp. from room temp. to 520°. The sample gas was introduced into the preconcentrator using a miniature air pump at a flow rate of 2.0 L/min. Four silicon microcantilevers in one silicon chip fabricated by micro-electromech. systems (MEMS) technol. were packaged in a ceramic flat package and driven by a PZT actuator plate mounted in the package. Using the 4th vibration mode (resonant frequency: 764 kHz) of a polybutadiene (2.52 μm thick)-coated cantilever, the sensitivity was 514 Hz/ppm for toluene and 850 Hz/ppm for p-xylene with a 5 min preconcn. time. The preconcn. factor and system efficiency of sensing were estd. to be 830 and 0.78, resp., for toluene. The estd. detection limit of the sensor system was less than 1 ppb for toluene and p-xylene with a 10 L sample vol., which was good enough for application to environmental monitoring. Sep. detection of the mixed toluene and p-xylene was also achieved in the form of different time peaks during the heating preconcentrator operation.
- 321Urbiztondo, M. A.; Peralta, A.; Pellejero, I.; Sesé, J.; Pina, M. P.; Dufour, I.; Santamaría, J. Detection of Organic Vapours with Si Cantilevers Coated with Inorganic (Zeolites) or Organic (Polymer) Layers Sens. Actuators, B 2012, 171–172, 822– 831 DOI: 10.1016/j.snb.2012.05.078Google Scholar321https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC38XpsVOqt7k%253D&md5=bfa150b4686fa6d11d7c6fb0c7e9b429Detection of organic vapours with Si cantilevers coated with inorganic (zeolites) or organic (polymer) layersUrbiztondo, M. A.; Peralta, A.; Pellejero, I.; Sese, J.; Pina, M. P.; Dufour, I.; Santamaria, J.Sensors and Actuators, B: Chemical (2012), 171-172 (), 822-831CODEN: SABCEB; ISSN:0925-4005. (Elsevier B.V.)Microfabricated Si cantilevers with different sensitive layers were used for the detection of volatile hydrocarbons (ethanol and toluene) in air at ppm concn. levels. A variety of coatings was explored, including several polymers (PEUT, PECH, PIB) and zeolites both organophilic (silicalite) and hydrophilic (zeolite Y, zeolite A). Also, different sensor dimensions were studied, in an attempt to understand the trade off between a larger sensor surface (and therefore a larger sensitive area) and better mech. properties. The main sensor performance parameters were calcd. and compared for the different coatings and sensor designs. Also, some scarcely studied aspects such as the evolution of the Q factor with zeolite loading were studied. Among the tested, detection limits <24 ppmV for ethanol and 26 ppmV for toluene were obtained with zeolite type coatings; while the corresponding values for the polymer-coated are over 260 and 43 ppmV, resp. The performance of zeolite-coated cantilevers could be further increased by degassing at a sufficiently high temp. to remove the adsorbed species, thus releasing their nanoporous structure for the next sensing cycle. To this end, cantilevers with integrated heaters were developed which enabled lowering the limits of detection down to the single ppm level.
- 322Compagnone, D.; Fusella, G. C.; Del Carlo, M.; Pittia, P.; Martinelli, E.; Tortora, L.; Paolesse, R.; Di Natale, C. Gold Nanoparticles-Peptide Based Gas Sensor Arrays for the Detection of Food Aromas Biosens. Bioelectron. 2013, 42, 618– 625 DOI: 10.1016/j.bios.2012.10.096Google Scholar322https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC3sXisVOqtr4%253D&md5=04ef626bf8280c363619afe8c8c9b26dGold nanoparticles-peptide based gas sensor arrays for the detection of food aromasCompagnone, D.; Fusella, G. C.; Del Carlo, M.; Pittia, P.; Martinelli, E.; Tortora, L.; Paolesse, R.; Di Natale, C.Biosensors & Bioelectronics (2013), 42 (), 618-625CODEN: BBIOE4; ISSN:0956-5663. (Elsevier B.V.)A gas sensor array based on peptide modified gold nanoparticles deposited onto 20 MHz quartz crystal microbalances has been realized. Glutathione and its constituting aminoacids and dipeptides have been used as ligands. A great increase in sensitivity (2 orders of magnitude) was achieved using gold nanoparticles vs. monolayer modified QCMs. The sensors have been characterized in terms of sensitivity for hexane, water, trimethylammine and ethanol. Highest sensitivity was found for water. The ability to discriminate typical food aromas as cis-3-hexenol, isopentylacetate, ethylacetate, and terpinen-4-ol dissolved in different solvents was studied using a gas sensor array constituted by gold nanoparticles modified with the glutathione peptides, thioglycolic acid and an heptapeptide. The array was found able to discriminate the food aromas, the response being dependent on the polarity of the solvent used. Tests on real olive oil samples gave a satisfactory sepn. among samples having defects vs. non defected samples demonstrating that this approach has high potential for the development of gas sensor arrays to be used in real samples.
- 323Lucklum, R.; Hauptmann, P. Quartz Crystal Microbalance: Mass Sensitivity, Viscoelasticity and Acoustic Amplification Sens. Actuators, B 2000, 70, 30– 36 DOI: 10.1016/S0925-4005(00)00550-5Google Scholar323https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD3cXosVSntb0%253D&md5=3043a18adf2b28c78dd8c1112efce2cfThe quartz crystal microbalance: mass sensitivity, viscoelasticity and acoustic amplificationLucklum, Ralf; Hauptmann, PeterSensors and Actuators, B: Chemical (2000), B70 (1-3), 30-36CODEN: SABCEB; ISSN:0925-4005. (Elsevier Science S.A.)Quartz crystal resonators (QCR) respond to surface mass and material properties of a film coated on their surface. The acoustic load acting at the surface of the resonator is a more general parameter to describe this dependence. It can be represented by a mass factor and an acoustic factor. The quotient of resistance increase and frequency shift can be used for the detn. of the acoustic factor, if the loss tangent of the coating is known. Viscoelastic properties of sensitive coatings can enhance the mass sensitivity of quartz crystal microbalance (QCM) sensors. Acoustic factor and acoustic amplification effective during chem. sensing are not the same. We further suggest a sensor concept, which is based on a bilayer arrangement. Acoustic amplification with a viscoelastic film and chem. sensitivity is sepd. With a proper selection of materials, the first layer realizes acoustic amplification while the (chem.) sensitive layer acts as a pure mass detector. Major sensor design parameters are the shear modulus and the thickness of the first layer; major challenge is the prepn. of a homogeneous and uniform first film.
- 324Yao, Y.; Xue, Y. Impedance Analysis of Quartz Crystal Microbalance Humidity Sensors Based on Nanodiamond/Graphene Oxide Nanocomposite Film Sens. Actuators, B 2015, 211, 52– 58 DOI: 10.1016/j.snb.2014.12.134Google Scholar324https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2MXhvFSit7g%253D&md5=28f888c0357aea17f377d26049ae85a6Impedance analysis of quartz crystal microbalance humidity sensors based on nanodiamond/graphene oxide nanocomposite filmYao, Yao; Xue, YajuanSensors and Actuators, B: Chemical (2015), 211 (), 52-58CODEN: SABCEB; ISSN:0925-4005. (Elsevier B.V.)In this work, detonation nanodiamond (DND)/graphene oxide (GO) nanocomposites with various wt. ratios were prepd. By combining with quartz crystal microbalance (QCM) technique, the humidity sensing properties of these nanocomposites sensors, including response sensitivity, humidity hysteresis, dynamic response and recovery, were studied through an impedance anal. method. The test results indicated that DND/GO nanocomposites showed high humidity response sensitivity, logarithmic linear response, fast response/recovery and small humidity hysteresis. Moreover, the influence of DND content in nanocomposite on the humidity response sensitivity and quality factor of the sensors has also been discussed. The results revealed that the increase of DND content in nanocomposite could enhance the humidity response sensitivity, but reduce the quality factor of the sensor. So, it is very necessary to select a suitable DND content in nanocomposite for balancing the sensitivity and quality factor. In addn., the reasons for the enhanced humidity sensing performance have also been discussed in detail. This work demonstrated that DND/GO nanocomposite is a promise candidate material for humidity sensing detection by combing with QCM technique.
- 325Fanget, S.; Hentz, S.; Puget, P.; Arcamone, J.; Matheron, M.; Colinet, E.; Andreucci, P.; Duraffourg, L.; Myers, E.; Roukes, M. L. Gas Sensors Based on Gravimetric Detection - A Review Sens. Actuators, B 2011, 160, 804– 821 DOI: 10.1016/j.snb.2011.08.066Google Scholar325https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC3MXhsVGmsL7L&md5=0e09fbb36213c5b670a107a3b61ea28aGas sensors based on gravimetric detection-A reviewFanget, S.; Hentz, S.; Puget, P.; Arcamone, J.; Matheron, M.; Colinet, E.; Andreucci, P.; Duraffourg, L.; Meyers, Ed.; Roukes, M. L.Sensors and Actuators, B: Chemical (2011), 160 (1), 804-821CODEN: SABCEB; ISSN:0925-4005. (Elsevier B.V.)A review. These last 10 years, smaller, less expensive, and higher performance sensors are required for gas sensing applications. To date no true detection principle has been recognized as the best candidate for such application. Microsytems or Micro/Nano ElectroMech. Systems (M/NEMS) used as gravimetric detectors are among the probable candidates. The technol. can indeed be manufd. en masse and can provide multi-gas analyzing platform. In this paper, we present a comprehensive overview of micro/nano sensors based on the gravimetric effect to detect an absorbed gas on top of their surfaces. The paper provides a comparison between different electromech. devices (Bulk Acoustic Wave, Surface Acoustic Wave, Capacitive Micro-machined Ultrasonic Transducer, Micro/Nano cantilevers) with an introduction to gas adsorption mechanisms, material selection, detection principles and design guidance useful to researchers or engineers.
- 326Vashist, S. K.; Vashist, P. Recent Advances in Quartz Crystal Microbalance-Based Sensors J. Sens. 2011, 2011, 571405 DOI: 10.1155/2011/571405Google ScholarThere is no corresponding record for this reference.
- 327Martin, S. J.; Frye, G. C. Surface Acoustic Wave Response to Changes in Viscoelastic Film Properties Appl. Phys. Lett. 1990, 57, 1867– 1869 DOI: 10.1063/1.104043Google Scholar327https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADyaK3MXisFKhsg%253D%253D&md5=2ebedf33c479a9ac1b186775cc121850Surface acoustic wave response to changes in viscoelastic film propertiesMartin, S. J.; Frye, G. C.Applied Physics Letters (1990), 57 (18), 1867-9CODEN: APPLAB; ISSN:0003-6951.Changes in viscoelastic properties of a triblock SBR rubber were monitored using polymer-coated surface acoustic wave devices. Glass transitions induced by temp. changes and absorption of gas phase species were obsd. The changes in wave propagation velocity and attenuation which accompany these transitions are explained using a Maxwell model to describe the viscoelastic properties of the film.
- 328Lucklum, R.; Hauptmann, P. ΔF - ΔR QCM Technique: An Approach to an Advanced Sensor Signal Interpretation Electrochim. Acta 2000, 45, 3907– 3916 DOI: 10.1016/S0013-4686(00)00451-5Google ScholarThere is no corresponding record for this reference.
- 329Rodahl, M.; Höök, F.; Krozer, A.; Brzezinski, P.; Kasemo, B. Quartz Crystal Microbalance Setup for Frequency and Q-Factor Measurements in Gaseous and Liquid Environments Rev. Sci. Instrum. 1995, 66, 3924– 3930 DOI: 10.1063/1.1145396Google Scholar329https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADyaK2MXntVWhu7w%253D&md5=34b7d7e586acf0471e75c241b82497feQuartz crystal microbalance setup for frequency and Q-factor measurements in gaseous and liquid environmentsRodahl, Michael; Hook, Fredrik; Krozer, Anatol; Brzezinski, Peter; Kasemo, BengtReview of Scientific Instruments (1995), 66 (7), 3924-30CODEN: RSINAK; ISSN:0034-6748. (American Institute of Physics)An exptl. setup has been constructed for simultaneous measurements of the frequency, the abs. Q factor, and the amplitude of oscillation of a quartz crystal microbalance (QCM). The tech. soln. allows operation in vacuum, air, or liq. The crystal is driven at its resonant frequency by an oscillator that can be intermittently disconnected causing the crystal oscillation amplitude to decay exponentially. From the recorded decay curve the abs. Q factor (calcd. from the decay time const.), the frequency of the freely oscillating crystal, and the amplitude of oscillation are obtained. All measurements are fully automated. One electrode of the QCM in our setup was connected to true ground which makes possible simultaneous electrochem. The performance is illustrated by expts. in fluids of varying viscosity (gas and liq.) and by protein adsorption in situ. We found, in addn. to the above results, that the amplitude of oscillation is not always directly proportional to the Q factor, as the commonly used theory states. This puts limitations on the customary use of the amplitude of oscillation as a measure of the Q factor.
- 330Wessendorf, K. O. The Lever Oscillator for Use in High Resistance Resonator Applications; Proc. 1993 Frequency Control Symp.; IEEE: New York, 1993; pp 711– 717.Google ScholarThere is no corresponding record for this reference.
- 331Kunugi, Y.; Nigorikawa, K.; Harima, Y.; Yamashita, K. A Selective Organic Vapour Sensor Based on Simultaneous Measurements of Changes of Mass and Resistance of a Poly(Pyrrole) Thin Film J. Chem. Soc., Chem. Commun. 1994, 873– 874 DOI: 10.1039/c39940000873Google ScholarThere is no corresponding record for this reference.
- 332Hwang, B. J.; Yang, J. Y.; Lin, C. W. Recognition of Alcohol Vapor Molecules by Simultaneous Measurements of Resistance Changes on Polypyrrole-Based Composite Thin Films and Mass Changes on a Piezoelectric Crystal Sens. Actuators, B 2001, 75, 67– 75 DOI: 10.1016/S0925-4005(00)00744-9Google Scholar332https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD3MXjtFSktLw%253D&md5=78c4ff4f3aed12fab6abe1894ad7915dRecognition of alcohol vapor molecules by simultaneous measurements of resistance changes on polypyrrole-based composite thin films and mass changes on a piezoelectric crystalHwang, B. J.; Yang, J. Y.; Lin, C. W.Sensors and Actuators, B: Chemical (2001), B75 (1-2), 67-75CODEN: SABCEB; ISSN:0925-4005. (Elsevier Science S.A.)A novel gas sensor is fabricated from simultaneous measurements of resistance changes on polypyrrole-based composite thin films and frequency changes on a piezoelec. crystal. Mol. species such as ethanol and methanol can be recognized by the (ΔR/Δf) values, where ΔR and Δf are the resistance and frequency change, resp. The ΔR/Δf value remaining const. at various concns. of detected gases is a characteristic index of a given kind of vapor mols. The ΔR/Δf value can be modified by the introduction of inert materials, including poly(ethylene oxide) (PEO) and polyacrylonitrile (PAN), into the conducting polymer matrix. The higher the ΔR/Δf value, the better is the recognition ability. The composite PPy/PEO (PEO = 7 g/L) film exhibits the best recognition for alc. vapor mols. among the studied sensing films. Meanwhile, the quant. anal. of the vapor mols. can be achieved by measuring the ΔR or Δf values.
- 333Ricco, A. J.; Martin, S. J. Multiple-Frequency SAW Devices for Chemical Sensing and Materials Characterization Sens. Actuators, B 1993, 10, 123– 131 DOI: 10.1016/0925-4005(93)80035-AGoogle ScholarThere is no corresponding record for this reference.
- 334Seidel, W.; Hesjedal, T. Multimode and Multifrequency Gigahertz Surface Acoustic Wave Sensors Appl. Phys. Lett. 2004, 84, 1407– 1409 DOI: 10.1063/1.1650040Google ScholarThere is no corresponding record for this reference.
- 335Yadava, R. D. S.; Kshetrimayum, R.; Khaneja, M. Multifrequency Characterization of Viscoelastic Polymers and Vapor Sensing Based on Saw Oscillators Ultrasonics 2009, 49, 638– 645 DOI: 10.1016/j.ultras.2009.03.006Google ScholarThere is no corresponding record for this reference.
- 336Höök, F.; Kasemo, B.; Nylander, T.; Fant, C.; Sott, K.; Elwing, H. Variations in Coupled Water, Viscoelastic Properties, and Film Thickness of a Mefp-1 Protein Film During Adsorption and Cross-Linking: A Quartz Crystal Microbalance with Dissipation Monitoring, Ellipsometry, and Surface Plasmon Resonance Study Anal. Chem. 2001, 73, 5796– 5804 DOI: 10.1021/ac0106501Google Scholar336https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A280%3ADC%252BD38%252Fms1ClsQ%253D%253D&md5=4c7ab5864de2bd0ac210f7d046d74bf9Variations in coupled water, viscoelastic properties, and film thickness of a Mefp-1 protein film during adsorption and cross-linking: a quartz crystal microbalance with dissipation monitoring, ellipsometry, and surface plasmon resonance studyHook F; Kasemo B; Nylander T; Fant C; Sott K; Elwing HAnalytical chemistry (2001), 73 (24), 5796-804 ISSN:0003-2700.We have measured the time-resolved adsorption kinetics of the mussel adhesive protein (Mefp-1) on a nonpolar, methyl-terminated (thiolated) gold surface, using three independent techniques: quartz crystal microbalance with dissipation monitoring (QCM-D), surface plasmon resonance, and ellipsometry. The QCM-D and ellipsometry data shows that, after adsorption to saturation of Mefp-1, cross-linking of the protein layer using NaIO4 transforms it from an extended (approximately 20 nm), water-rich, and hydrogel-like state to a much thinner (approximately 5 nm), compact, and less water-rich state. Furthermore, we show how quantitative data about the thickness, shear elastic modulus, and shear viscosity of the protein film can be obtained with the QCM-D technique, even beyond the Sauerbrey regime, if frequency (f) and energy dissipation (D) measurements measured at multiple harmonics are combined with theoretical simulations using a Voight-based viscoelastic model. The modeling result was confirmed by substituting H2O for D2O. As expected, the D2O substitution does not influence the actual adsorption behavior, but resulted in expected differences in the estimated effective density and shear viscosity. These results provide new insight and understanding about the adsorption kinetics and crosslinking behavior of Mefp-1. They also demonstrate how the above three techniques complement each other for biomolecule adsorption studies.
- 337Potyrailo, R. A.; Nagraj, N.; Lee, Y.; Surman, C.; Slocik, J. M.; Gallagher, D. M.; Hagen, J. A.; Naik, R. R.; Kelley-Loughnane, N.; Lyon, W.Evaluation of Peptide-Capped Gold Nanoparticle Networks for Vapor Sensing at MHz and GHz Spectral Regions; 2011 Chem. Biol. Defense Sci. Technol. (CBD S&T) Conf.: 2011; W11-009.Google ScholarThere is no corresponding record for this reference.
- 338Lundström, I.; Shivaraman, S.; Svensson, C.; Lundkvist, L. A Hydrogen-Sensitive MOS Field-Effect Transistor Appl. Phys. Lett. 1975, 26, 55– 57 DOI: 10.1063/1.88053Google Scholar338https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADyaE2MXhtlagtrk%253D&md5=aecbc047700891fff485ab59b94b396dHydrogen-sensitive MOS [metal oxide semiconductor] field-effect transistorLundstrom, I.; Shivaraman, S.; Svensson, C.; Lundkvist, L.Applied Physics Letters (1975), 26 (2), 55-7CODEN: APPLAB; ISSN:0003-6951.An MOS transistor in Si with 10-nm SiO2 as gate insulator and 10-nm Pd gate electrode was fabricated. The threshold voltage of this transistor was a function of the partial pressure of H in the ambient atm. At a device temp. of 150° it was possible to detect 40-ppm H gas in air with response times <2 min.
- 339Andringa, A. M.; Piliego, C.; Katsouras, I.; Blom, P. W. M.; Leeuw, D. M. D. NO2 Detection and Real-Time Sensing with Field-Effect Transistors Chem. Mater. 2014, 26, 773– 785 DOI: 10.1021/cm4020628Google Scholar339https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC3sXhtlChsLrM&md5=0d94f8f4d9d756b76a297c4b988f3395NO2 Detection and Real-Time Sensing with Field-Effect TransistorsAndringa, Anne-Marije; Piliego, Claudia; Katsouras, Ilias; Blom, Paul W. M.; Leeuw, Dago M. deChemistry of Materials (2014), 26 (1), 773-785CODEN: CMATEX; ISSN:0897-4756. (American Chemical Society)A review. The huge impact of nitrogen dioxide (NO2) emission on public health and the environment is motivating extensive scientific and technol. research in the field of NO2 sensing. Field-effect transistors have emerged as a sensitive and reliable technol. for monitoring air quality, due to their amplified sensor response. In this review article, the NO2 detection mechanism with field-effect transistors is discussed. The origin is charge trapping at the gate dielec., yielding a threshold voltage shift. The dynamic response can be described by an anal. model. Implementation in a sensor protocol allows for the fabrication of a functional demonstrator. The sensor, based on a ZnO field-effect transistor, is capable of detecting concns. ≥40 ppb of NO2 in real-time. The sensor operates in ambient air, and apart from drying, no further precautions are taken, showing that the fabricated sensor is selective for NO2. The results reviewed in this paper set a precedent for sensing with field-effect transistors.
- 340Han, J. W.; Rim, T.; Baek, C. K.; Meyyappan, M. Chemical Gated Field Effect Transistor by Hybrid Integration of One-Dimensional Silicon Nanowire and Two-Dimensional Tin Oxide Thin Film for Low Power Gas Sensor ACS Appl. Mater. Interfaces 2015, 7, 21263– 21269 DOI: 10.1021/acsami.5b05479Google Scholar340https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2MXhsFChsbfN&md5=638d6c34d6041f677b83a43c6dff303bChemical Gated Field Effect Transistor by Hybrid Integration of One-Dimensional Silicon Nanowire and Two-Dimensional Tin Oxide Thin Film for Low Power Gas SensorHan, Jin-Woo; Rim, Taiuk; Baek, Chang-Ki; Meyyappan, M.ACS Applied Materials & Interfaces (2015), 7 (38), 21263-21269CODEN: AAMICK; ISSN:1944-8244. (American Chemical Society)Gas sensors based on metal-oxide-semiconductor transistor with the polysilicon gate replaced by a gas sensitive thin film were around for over 50 years. These are not suitable for the emerging mobile and wearable sensor platforms due to operating voltages and powers far exceeding the supply capability of batteries. Here the authors present a novel approach to decouple the chem. sensitive region from the conducting channel for reducing the drive voltage and increasing reliability. This chem. gated field effect transistor uses silicon nanowire for the current conduction channel with a tin oxide film on top of the nanowire serving as the gas sensitive medium. The potential change induced by the mol. adsorption and desorption allows the elec. floating tin oxide film to gate the silicon channel. As the device is designed to be normally off, the power is consumed only during the gas sensing event. This feature is attractive for the battery operated sensor and wearable electronics. The decoupling of the chem. reaction and the current conduction regions allows the gas sensitive material to be free from elec. stress, thus increasing reliability. The device shows excellent gas sensitivity to the tested analytes relative to conventional metal oxide transistors and resistive sensors.
- 341Lundström, I.; Armgarth, M.; Spetz, A.; Winquist, F. Gas Sensors Based on Catalytic Metal-Gate Field-Effect Devices Sens. Actuators 1986, 10, 399– 421 DOI: 10.1016/0250-6874(86)80056-7Google ScholarThere is no corresponding record for this reference.
- 342Gergintschew, Z.; Kornetzky, P.; Schipanski, D. The Capacitively Controlled Field Effect Transistor (CCFET) as a New Low Power Gas Sensor Sens. Actuators, B 1996, 36, 285– 289 DOI: 10.1016/S0925-4005(97)80083-4Google Scholar342https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADyaK2sXmsFeqsg%253D%253D&md5=0222b8e55ed3e8229c086a80ac9fef70The capacitively controlled field effect transistor (CCFET) as a new low power gas sensorGergintschew, Zenko; Kornetzky, Peter; Schipanski, DagmarSensors and Actuators, B: Chemical (1996), 36 (1-3, Proceedings of the Sixth International Meeting on Chemical Sensors, 1996), 285-289CODEN: SABCEB; ISSN:0925-4005. (Elsevier)The operating principle of a new work function gas sensor, the capacitively controlled field effect transistor (CCFET) is presented. It consists of a capacitor with an air gap and a field effect transistor. Three different CCFET-structures (based on a std. CMOS technol.) are realized: discrete, hybrid and integrated. An optimized operating and guard circuit for the CCFET is also presented. The sensor properties are discussed along with their responses to H2, NH3 and C6H6 at temps. ranging from room temp. to 60°. Pd and Ga2O3 were used for the gas sensitive layer.
- 343Sensistor ISH2000 Technical Reference Manual; 2012; www.inficon.com (accessed August 27, 2016).Google ScholarThere is no corresponding record for this reference.
- 344Nakata, S.; Shimanoe, K.; Miura, N.; Yamazoe, N. Field Effect Transistor Type NO2 Sensor Combined with NaNO2 Auxiliary Phase Sens. Actuators, B 2001, 77, 512– 516 DOI: 10.1016/S0925-4005(01)00714-6Google Scholar344https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD3MXksFSkurg%253D&md5=cfc68dca7aa94ee1fdf89b67c5117e35Field effect transistor type NO2 sensor combined with NaNO2 auxiliary phaseNakata, S.; Shimanoe, K.; Miura, N.; Yamazoe, N.Sensors and Actuators, B: Chemical (2001), 77 (1-2), 512-516CODEN: SABCEB; ISSN:0925-4005. (Elsevier Science B.V.)A field effect transistor (FET) sensor for NO2 was fabricated by depositing an NaNO2 layer together with an Au electrode over the gate area. The NaNO2-attached FET exhibited almost ideal FET behavior at 180° in air. The threshold voltage was found to shift up ward in a well controlled manner with increasing NO2 concn. of the atm. Under the condition of a fixed source-drain voltage (3.0 V), the gate-source voltage (VGS) necessary to keep the drain current at a small const. value (200 μA) increases linearly with an increase in the logarithm of NO2 concn. in the range from 500 ppb to 10 ppm. The times of 90% response and recovery to switching-on and -off 500 ppb NO2 were ∼2 and 4 min, resp. The NO2 sensitivity was hardly or only slightly affected by variations in the concns. of coexistent O2, CO2 or H2O.
- 345Huck, C.; Poghossian, A.; Bäcker, M.; Reisert, S.; Kramer, F.; Begoyan, V. K.; Buniatyan, V. V.; Schöning, M. J. Multi-Parameter Sensing Using High-K Oxide of Barium Strontium Titanate Phys. Status Solidi A 2015, 212, 1254– 1259 DOI: 10.1002/pssa.201431911Google ScholarThere is no corresponding record for this reference.
- 346Puglisi, D.; Eriksson, J.; Andersson, M.; Huotari, J.; Bastuck, M.; Bur, C.; Lappalainen, J.; Schuetze, A.; Lloyd Spetz, A. Exploring the Gas Sensing Performance of Catalytic Metal/Metal Oxide 4H-SiC Field Effect Transistors Mater. Sci. Forum 2016, 858, 997– 100Google ScholarThere is no corresponding record for this reference.
- 347Mwakikunga, B.; Singh, T.; Giebelhaus, I.; Fischer, T.; Lepcha, A.; Gad, A. E.; Faglia, G.; Mathur, S. Development of Single-, Few- and Multiple-Nanowire Gas-Sensor Two-Terminal Devices on Ceramic Substrates and Characterization by Impedance Spectroscopy. In Nanostructured Materials and Nanotechnology VII; Mathur, S.; Hernandez-Ramirez, F.; Kirihara, S.; Widjaja, S., Eds.; Wiley: Hoboken, NJ, 2013; pp 149– 155.Google ScholarThere is no corresponding record for this reference.
- 348Feng, P.; Shao, F.; Shi, Y.; Wan, Q. Gas Sensors Based on Semiconducting Nanowire Field-Effect Transistors Sensors 2014, 14, 17406– 17429 DOI: 10.3390/s140917406Google Scholar348https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2MXitVWktLg%253D&md5=5d71b1f250a74cdd162a1c2eb46e1defGas sensors based on semiconducting nanowire field-effect transistorsFeng, Ping; Shao, Feng; Shi, Yi; Wan, QingSensors (2014), 14 (9), 17406-17429, 24 pp.CODEN: SENSC9; ISSN:1424-8220. (MDPI AG)A review. One-dimensional semiconductor nanostructures are unique sensing materials for the fabrication of gas sensors. In this article, gas sensors based on semiconducting nanowire field-effect transistors (FETs) are comprehensively reviewed. Individual nanowires or nanowire network films are usually used as the active detecting channels. In these sensors, a third electrode, which serves as the gate, is used to tune the carrier concn. of the nanowires to realize better sensing performance, including sensitivity, selectivity and response time, etc. The FET parameters can be modulated by the presence of the target gases and their change relate closely to the type and concn. of the gas mols. In addn., extra controls such as metal decoration, local heating and light irradn. can be combined with the gate electrode to tune the nanowire channel and realize more effective gas sensing. With the help of micro-fabrication techniques, these sensors can be integrated into smart systems. Finally, some challenges for the future investigation and application of nanowire field-effect gas sensors are discussed.
- 349Late, D. J.; Huang, Y. K.; Liu, B.; Acharya, J.; Shirodkar, S. N.; Luo, J.; Yan, A.; Charles, D.; Waghmare, U. V.; Dravid, V. P.; Rao, C. N. R. Sensing Behavior of Atomically Thin-Layered MoS2 Transistors ACS Nano 2013, 7, 4879– 4891 DOI: 10.1021/nn400026uGoogle Scholar349https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC3sXosVejsrc%253D&md5=710558db5c9062b00d199e30d2f8532fSensing Behavior of Atomically Thin-Layered MoS2 TransistorsLate, Dattatray J.; Huang, Yi-Kai; Liu, Bin; Acharya, Jagaran; Shirodkar, Sharmila N.; Luo, Jiajun; Yan, Aiming; Charles, Daniel; Waghmare, Umesh V.; Dravid, Vinayak P.; Rao, C. N. R.ACS Nano (2013), 7 (6), 4879-4891CODEN: ANCAC3; ISSN:1936-0851. (American Chemical Society)Most of recent research on layered chalcogenides is understandably focused on single at. layers. However, it is unclear if single-layer units are the most ideal structures for enhanced gas-solid interactions. To probe this issue further, we have prepd. large-area MoS2 sheets ranging from single to multiple layers on 300 nm SiO2/Si substrates using the micromech. exfoliation method. The thickness and layering of the sheets were identified by optical microscope, invoking recently reported specific optical color contrast, and further confirmed by AFM and Raman spectroscopy. The MoS2 transistors with different thicknesses were assessed for gas-sensing performances with exposure to NO2, NH3, and humidity in different conditions such as gate bias and light irradn. The results show that, compared to the single-layer counterpart, transistors of few MoS2 layers exhibit excellent sensitivity, recovery, and ability to be manipulated by gate bias and green light. Further, our ab initio DFT calcns. on single-layer and bilayer MoS2 show that the charge transfer is the reason for the decrease in resistance in the presence of applied field.
- 350Kim, Y.; An, T. K.; Kim, J.; Hwang, J.; Park, S.; Nam, S.; Cha, H.; Park, W. J.; Baik, J. M.; Park, C. E. A Composite of a Graphene Oxide Derivative as a Novel Sensing Layer in an Organic Field-Effect Transistor J. Mater. Chem. C 2014, 2, 4539– 4544 DOI: 10.1039/c4tc00376dGoogle Scholar350https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2cXotlyqsrw%253D&md5=7cfc4eb063c456c1797bc403b049561bA composite of a graphene oxide derivative as a novel sensing layer in an organic field-effect transistorKim, Yebyeol; An, Tae Kyu; Kim, Jiye; Hwang, Jihun; Park, Seonuk; Nam, Sooji; Cha, Hyojung; Park, Won Jeong; Baik, Jeong Min; Park, Chan EonJournal of Materials Chemistry C: Materials for Optical and Electronic Devices (2014), 2 (23), 4539-4544CODEN: JMCCCX; ISSN:2050-7534. (Royal Society of Chemistry)We report the fabrication of a gas sensor with an oleylamine-modified graphene oxide (OA-GO)/poly(9-9'-dioctyl-fluorene-co-bithiophene) (F8T2) composite as an active layer and demonstrate that it has better sensing ability than a comparable device with an F8T2-only active layer. OA-GO was chosen as the receptor material because of its enhanced interaction with gas analytes and its easy mixing with F8T2. OA-GO was synthesized by a simple condensation reaction between GO and oleylamine (9-octadecylamine), and characterized by Fourier transform IR spectroscopy. The sensitivities of the gas sensors with respect to acetone and ethanol analytes were investigated by measuring the elec. parameters of the corresponding org. field effect transistor at room temp. The sensitivity of the OA-GO/F8T2 composite device was up to 34 times that of the F8T2 device for the mobility change of acetone.
- 351Torsi, L.; Farinola, G. M.; Marinelli, F.; Tanese, M. C.; Omar, O. H.; Valli, L.; Babudri, F.; Palmisano, F.; Zambonin, G.; Naso, F. A Sensitivity-Enhanced Field-Effect Chiral Sensor Nat. Mater. 2008, 7, 412– 417 DOI: 10.1038/nmat2167Google Scholar351https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD1cXltVGktbk%253D&md5=afad3322d7b8f222ea49ff468636f2a2A sensitivity-enhanced field-effect chiral sensorTorsi, Luisa; Farinola, Gianluca M.; Marinelli, Francesco; Tanese, M. Cristina; Omar, Omar Hassan; Valli, Ludovico; Babudri, Francesco; Palmisano, Francesco; Zambonin, P. Giorgio; Naso, FrancescoNature Materials (2008), 7 (5), 412-417CODEN: NMAACR; ISSN:1476-1122. (Nature Publishing Group)Org. thin-film transistor sensors were recently attracting the attention of the plastic electronics community for their potential exploitation in novel sensing platforms. Specificity and sensitivity are however still open issues: in this respect chiral discrimination-being a scientific and technol. achievement in itself-is indeed one of the most challenging sensor bench-tests. So far, conducting-polymer solid-state chiral detection was carried out at part-per-thousand concn. levels. Here, a novel chiral bilayer org. thin-film transistor gas sensor-comprising an outermost layer with built-in enantioselective properties-is demonstrated to show field-effect amplified sensitivity that enables differential detection of optical isomers in the tens-of-parts-per-million concn. range. The ad-hoc-designed org. semiconductor endowed with chiral side groups, the bilayer structure and the thin-film transistor transducer provide a significant step forward in the development of a high-performance and versatile sensing platform compatible with flexible org. electronic technologies.
- 352Roberts, M. E.; Sokolov, A. N.; Bao, Z. Material and Device Considerations for Organic Thin-Film Transistor Sensors J. Mater. Chem. 2009, 19, 3351– 3363 DOI: 10.1039/b816386cGoogle Scholar352https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD1MXmtFequ7o%253D&md5=23026f91cb83a144b22be1bc3a5970dcMaterial and device considerations for organic thin-film transistor sensorsRoberts, Mark E.; Sokolov, Anatoliy N.; Bao, ZhenanJournal of Materials Chemistry (2009), 19 (21), 3351-3363CODEN: JMACEP; ISSN:0959-9428. (Royal Society of Chemistry)A review. The rapid development of the field of org. electronics has sparked great interest in the use of org. thin-film transistors (OTFTs) as low-cost electronic sensors. The direct coupling of the electronic and the sensor media to provide real time elec. output has already demonstrated high sensitivity to a variety of chem. species. The synthetic versatility of org. materials also provides endless routes to impart functionality for specifically targeted chem. interactions. Owing to their compatibility with flexible materials and simple fabrication methods, OTFTs are poised to have a tremendous impact on future portable detection technol. This article reviews recent progress made toward improved sensitivity, selectivity and stability of OTFT sensors through material and device engineering. Specific consideration is paid to the interaction of the electronic materials with the analytes as a means of providing insight into mechanistic principles as well as the future direction of OTFTs.
- 353Ryu, G.-S.; Park, K. H.; Park, W.-T.; Kim, Y.-H.; Noh, Y.-Y. High-Performance Diketopyrrolopyrrole-Based Organic Field-Effect Transistors for Flexible Gas Sensors Org. Electron. 2015, 23, 76– 81 DOI: 10.1016/j.orgel.2015.04.001Google Scholar353https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2MXms1yiuro%253D&md5=a08f51eff684beab05e03cea30998eabHigh-performance diketopyrrolopyrrole-based organic field-effect transistors for flexible gas sensorsRyu, Gi-Seong; Park, Kwang Hun; Park, Won-Tae; Kim, Yun-Hi; Noh, Yong-YoungOrganic Electronics (2015), 23 (), 76-81CODEN: OERLAU; ISSN:1566-1199. (Elsevier B.V.)We demonstrate high-performance flexible polymer OFETs with P-29-DPP-SVS in various geometries. The mobilities of TG/BC OFETs are approx. 3.48 ± 0.93 cm2/V s on a glass substrate and 2.98 ± 0.19 cm2/V s on a PEN substrate. The flexible P-29-DPP-SVS OFETs exhibit excellent ambient and mech. stabilities under a continuous bending stress of 1200 times at an R = 8.3 mm. In particular, the variation of μFET, VTh and leakage current was very negligible (below 10%) after continuous bending stress. The BG/TC P-29-DPP-SVS OFETs on a PEN substrate applies to flexible NH3 gas sensors. As the concn. of NH3 increased, the channel resistance of P-29-DPP-SVS OFETs increased approx. 100 times from ∼107 to ∼109 Ω at VSD = -5 V and VGS = -5 V.
- 354Paska, Y.; Stelzner, T.; Christiansen, S.; Haick, H. Enhanced Sensing of Nonpolar Volatile Organic Compounds by Silicon Nanowire Field Effect Transistors ACS Nano 2011, 5, 5620– 5626 DOI: 10.1021/nn201184cGoogle Scholar354https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC3MXntFSmsbg%253D&md5=711f4307baad94c4b7aaaa0e5c2f3b83Enhanced Sensing of Nonpolar Volatile Organic Compounds by Silicon Nanowire Field Effect TransistorsPaska, Yair; Stelzner, Thomas; Christiansen, Silke; Haick, HossamACS Nano (2011), 5 (7), 5620-5626CODEN: ANCAC3; ISSN:1936-0851. (American Chemical Society)Silicon nanowire field effect transistors (Si NW FETs) are emerging as powerful sensors for direct detection of biol. and chem. species. However, the low sensitivity of the Si NW FET sensors toward nonpolar volatile org. compds. (VOCs) is problematic for many applications. Modifying Si NW FETs with a silane monolayer having a low fraction of Si-O-Si bonds between the adjacent mols. greatly enhances the sensitivity toward nonpolar VOCs. This can be explained in terms of an indirect sensor-VOC interaction, whereby the nonpolar VOC mols. induce conformational changes in the org. monolayer, affecting (i) the dielec. const. and/or effective dipole moment of the org. monolayer and/or (ii) the d. of charged surface states at the SiO2/monolayer interface. In contrast, polar VOCs are sensed directly via VOC-induced changes in the Si NW charge carriers, most probably due to electrostatic interaction between the Si NW and polar VOCs. A semiempirical model for the VOC-induced cond. changes in the Si NW FETs is presented and discussed.
- 355Torsi, L.; Dodabalapur, A. Organic Thin-Film Transistors as Plastic Analytical Sensors Anal. Chem. 2005, 77, 380A– 387A DOI: 10.1021/ac053475nGoogle Scholar355https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD2MXhtVOqtbrN&md5=8b5e64a17cbad54e37b4bf85c67d31caOrganic thin-film transistors as plastic analytical sensorsTorsi, Luisa; Dodabalapur, AnanthAnalytical Chemistry (2005), 77 (19), 380A-387ACODEN: ANCHAM; ISSN:0003-2700. (American Chemical Society)A review. Org. thin-film transistors (OTFTs) can act as multiparametric sensors with remarkable response repeatability and as semiconducting polymer-based sensing circuits. The authors discuss the properties and limitations of OTFT sensors.
- 356Mabeck, J. T.; Malliaras, G. G. Chemical and Biological Sensors Based on Organic Thin-Film Transistors Anal. Bioanal. Chem. 2006, 384, 343– 353 DOI: 10.1007/s00216-005-3390-2Google Scholar356https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD28XhsF2jug%253D%253D&md5=b326bf716a46b556d53316ef52a6efa6Chemical and biological sensors based on organic thin-film transistorsMabeck, Jeffrey T.; Malliaras, George G.Analytical and Bioanalytical Chemistry (2006), 384 (2), 343-353CODEN: ABCNBP; ISSN:1618-2642. (Springer)A review. The application of org. thin-film transistors (OTFTs) to chem. and biol. sensing is reviewed. This review covers transistors that are based on the modulation of current through thin org. semiconducting films, and includes both field-effect and electrochem. transistors. The advantages of using OTFTs as sensors (including high sensitivity and selectivity) are described, and results are presented for sensing analytes in both gaseous and aq. environments. The primary emphasis is on the major developments in the field of OTFT sensing over the last 5-10 years, but some earlier work is discussed briefly to provide a foundation.
- 357Bouvet, M. Phthalocyanine-Based Field-Effect Transistors as Gas Sensors Anal. Bioanal. Chem. 2006, 384, 366– 373 DOI: 10.1007/s00216-005-3257-6Google Scholar357https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD28XhsF2jtQ%253D%253D&md5=877f0f47df5a7a1ff464220c1840a900Phthalocyanine-based field-effect transistors as gas sensorsBouvet, MarcelAnalytical and Bioanalytical Chemistry (2006), 384 (2), 366-373CODEN: ABCNBP; ISSN:1618-2642. (Springer)A review. In this review mol. field-effect transistors are described and compared with their gate-modified inorg. counterparts. The different processes involved in gas sensing are summarized. The advantages of transistors on resistors are demonstrated. The sensitivity of mol. field-effect transistors to strong oxidizing species, for example ozone, is detailed and compared with their sensitivity to humidity and volatile org. compds. Application to ozone monitoring in urban atms. is also described.
- 358Lin, P.; Yan, F. Organic Thin-Film Transistors for Chemical and Biological Sensing Adv. Mater. 2012, 24, 34– 51 DOI: 10.1002/adma.201103334Google Scholar358https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC3MXhsV2rurrO&md5=90da6964fb55fa6c5b63c5ba88ab3f8eOrganic Thin-Film Transistors for Chemical and Biological SensingLin, Peng; Yan, FengAdvanced Materials (Weinheim, Germany) (2012), 24 (1), 34-51CODEN: ADVMEW; ISSN:0935-9648. (Wiley-VCH Verlag GmbH & Co. KGaA)A review. Org. thin-film transistors (OTFTs) show promising applications in various chem. and biol. sensors. The advantages of OTFT-based sensors include high sensitivity, low cost, easy fabrication, flexibility and biocompatibility. The authors review the chem. sensors and biosensors based on two types of OTFTs, including org. field-effect transistors (OFETs) and org. electrochem. transistors (OECTs), mainly focusing on the papers published in the past 10 years. Various types of OTFT-based sensors, including pH, ion, glucose, DNA, enzyme, antibody-antigen, cell-based sensors, dopamine sensor, etc., are classified and described in the paper in sequence. The sensing mechanisms and the detection limits of the devices are described in details. It is expected that OTFTs may have more important applications in chem. and biol. sensing with the development of org. electronics.
- 359Torsi, L.; Magliulo, M.; Manoli, K.; Palazzo, G. Organic Field-Effect Transistor Sensors: A Tutorial Review Chem. Soc. Rev. 2013, 42, 8612– 8628 DOI: 10.1039/c3cs60127gGoogle Scholar359https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC3sXhs1CmurnP&md5=94acce4ac9c06f286d4066f54889f1d1Organic field-effect transistor sensors: a tutorial reviewTorsi, Luisa; Magliulo, Maria; Manoli, Kyriaki; Palazzo, GerardoChemical Society Reviews (2013), 42 (22), 8612-8628CODEN: CSRVBR; ISSN:0306-0012. (Royal Society of Chemistry)A review. The functioning principles of electronic sensors based on org. semiconductor field-effect transistors (OFETs) are presented. The focus is on biol. sensors but also chem. ones are reviewed to address general features. The field-induced electronic transport and the chem. and biol. interactions for the sensing, each occurring at the relevant functional interface, are sep. introduced. Once these key learning points have been acquired, the combined picture for the FET electronic sensing is proposed. The perspective use of such devices in point-of-care is introduced, after some basics on anal. biosensing systems are provided as well. This tutorial review includes also a necessary overview of the OFET sensing structures, but the focus will be on electronic rather than electrochem. detection. The differences among the structures are highlighted along with the implications on the performance level in terms of key anal. figures of merit such as: repeatability, sensitivity and selectivity.
- 360Demelas, M.; Lai, S.; Cosseddu, P.; Loi, A.; Barbaro, M.; Bonfiglio, A. Chemical Sensors Using Organic Thin-Film Transistors (OTFTs) Handbook of Flexible Organic Electronics: Materials, Manufacturing and Applications 2015, 375– 396 DOI: 10.1016/B978-1-78242-035-4.00015-4Google ScholarThere is no corresponding record for this reference.
- 361Zhang, C.; Chen, P.; Hu, W. Organic Field-Effect Transistor-Based Gas Sensors Chem. Soc. Rev. 2015, 44, 2087– 2107 DOI: 10.1039/C4CS00326HGoogle Scholar361https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2MXjsF2rtrc%253D&md5=e0990e4fe502ed02193af490ad7310b1Organic field-effect transistor-based gas sensorsZhang, Congcong; Chen, Penglei; Hu, WenpingChemical Society Reviews (2015), 44 (8), 2087-2107CODEN: CSRVBR; ISSN:0306-0012. (Royal Society of Chemistry)Org. field-effect transistors (OFETs) are one of the key components of modern org. electronics. While the past several decades have witnessed huge successes in high-performance OFETs, their sophisticated functionalization with regard to the responses towards external stimulations has also aroused increasing attention and become an important field of general concern. This is promoted by the inherent merits of org. semiconductors, including considerable variety in mol. design, low cost, light wt., mech. flexibility, and soln. processability, as well as by the intrinsic advantages of OFETs including multiparameter accessibility and ease of large-scale manufg., which provide OFETs with great potential as portable yet reliable sensors offering high sensitivity, selectivity, and expeditious responses. With special emphases on the works achieved since 2009, this tutorial review focuses on OFET-based gas sensors. The working principles of this type of gas sensors are discussed in detail, the state-of-the-art protocols developed for high-performance gas sensing are highlighted, and the advanced gas discrimination systems in terms of sensory arrays of OFETs are also introduced. This tutorial review intends to provide readers with a deep understanding for the future design of high-quality OFET gas sensors for potential uses.
- 362Bae, J.; Kim, I. T.; Hur, J. Field-Effect Transistors Based on Organic and Carbon-Based Materials for Chemical and Biological Sensors Curr. Org. Chem. 2015, 19, 1176– 1190 DOI: 10.2174/1385272819666150318222230Google Scholar362https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2MXhtFWqu73N&md5=b337858308a0e3f85b150d062ee06a19Field-Effect Transistors Based on Organic and Carbon-Based Materials for Chemical and Biological SensorsBae, Joonwon; Kim, Il T.; Hur, JaehyunCurrent Organic Chemistry (2015), 19 (12), 1176-1190CODEN: CORCFE; ISSN:1385-2728. (Bentham Science Publishers Ltd.)Electronic sensors have been considered as essential elements for chem. and biol. detection in a standalone miniaturized form or in a fully integrated system. The field-effect transistor based on org. material is an emerging device that has drawn tremendous attention because of its many beneficial features such as light wt., mech. flexibility, facile chem. modification, and low-cost processes. Given the progress in related fields-e.g., org. light emitting diodes (OLEDs), org. photovoltaics (OPVs), and org. thin film transistors (OTFTs)-the appropriate coupling of these technologies with sensors is actively expanding, with new ideas and exptl. approaches. To reach the ultimate goal of high performance in terms of sensitivity, selectivity, stability, and response time, many concepts have been proposed. This review article summarizes recent research activities on chem. and biol. field-effect transistors sensors based on org. and carbon materials. In particular, we highlight the different levels of performance obtained using a variety of org. semiconducting materials.
- 363Popova, L. I.; Andreev, S. K.; Gueorguiev, V. K.; Stoyanov, N. D. Voltage Dependence of Gas-Sensing Behaviour of SnO2-Gate FETs Sens. Actuators, B 1994, 19, 543– 545 DOI: 10.1016/0925-4005(93)01080-NGoogle Scholar363https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADyaK2cXlsVOrs7s%253D&md5=48a478f0717d922d4f8ee79906ed77fevoltage dependence of gas-sensing behavior of SnO2-gate FETsPopova, L. I.; Andreev, S. K.; Gueorguiev, V. K.; Stoyanov, N. D.Sensors and Actuators, B: Chemical (1994), 19 (1-3), 543-5CODEN: SABCEB; ISSN:0925-4005.SnO2-gate FETs with NH3-sensing behavior are studied at const. NH3 concn. (100 ppm) and different bias conditions. Strong dependence of the sensing behavior on the drain and gate voltage (VD, VG) applied is obsd. The current response obtained could be pos., neg. or zero at different bias conditions. From the interpretation of the exptl. data 2 conclusions are deduced: that the presence of NH3 in the air results in effective contributions ΔVG to the VG applied elec. and that the working mechanism is generally dependent on the transversal elec. field between the gate and the channel. However, there exists an addnl. dependence on VD and, thus, the obsd. sensing behavior cannot be explained by polarization or work function variations, or charge storage effects originating from the transversal field alone.
- 364Nakagomi, S.; Fukumura, A.; Kokubun, Y.; Savage, S.; Wingbrant, H.; Andersson, M.; Lundström, I.; Löfdahl, M.; Spetz, A. L. Influence of Gate Bias of MISiC-FET Gas Sensor Device on the Sensing Properties Sens. Actuators, B 2005, 108, 501– 507 DOI: 10.1016/j.snb.2004.11.057Google Scholar364https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD2MXltFWms7g%253D&md5=cc18acbc699b7167b5f6eb2288d0306fInfluence of gate bias of MISiC-FET gas sensor device on the sensing propertiesNakagomi, Shinji; Fukumura, Akira; Kokubun, Yoshihiro; Savage, Susan; Wingbrant, Helena; Andersson, Mike; Lundstroem, Ingemer; Loefdahl, Mikael; Spetz, Anita LloydSensors and Actuators, B: Chemical (2005), 108 (1-2), 501-507CODEN: SABCEB; ISSN:0925-4005. (Elsevier B.V.)The influence of gate bias on the gas sensing properties of SiC-based field effect transistors with catalytic gate and a buried short channel was studied. The drain current-voltage (Id-VD) characteristics of the device reveal nonsatn. property, which is a consequence of the short channel design. The drain current is larger in hydrogen ambient than in oxygen ambient at the same drain voltage. The threshold voltage decreases with increasing pos. gate bias, and increases with increasing neg. gate bias. When a pos. bias is applied to the gate, the Id-VD characteristics reveal a tendency to sat. A pos. gate bias increases the drain voltage response to hydrogen, as compared with a neg. applied gate bias. However, a pos. gate bias decreases the stability of the device signal. A change in the channel resistivity is the main reason for the change in the elec. properties when a pos. gate bias is applied. A phys. model that explains the influence of the gate bias was studied, and the behavior of the barrier height in the channel was estd. by using the temp. dependence of the Id-VD characteristics.
- 365Bur, C.; Bastuck, M.; Puglisi, D.; Schütze, A.; Lloyd Spetz, A.; Andersson, M. Discrimination and Quantification of Volatile Organic Compounds in the ppb-Range with Gas Sensitive SiC-FETs Using Multivariate Statistics Sens. Actuators, B 2015, 214, 225– 233 DOI: 10.1016/j.snb.2015.03.016Google Scholar365https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2MXltFems7w%253D&md5=49a1bf331c452d67c0159d787cd4b357Discrimination and quantification of volatile organic compounds in the ppb-range with gas sensitive SiC-FETs using multivariate statisticsBur, Christian; Bastuck, Manuel; Puglisi, Donatella; Schutze, Andreas; Lloyd Spetz, Anita; Andersson, MikeSensors and Actuators, B: Chemical (2015), 214 (), 225-233CODEN: SABCEB; ISSN:0925-4005. (Elsevier B.V.)Gas sensitive field effect transistors based on silicon carbide, SiC-FETs, have been studied for indoor air quality applications. The selectivity of the sensors was increased by temp. cycled operation, TCO, and data evaluation based on multivariate statistics. Discrimination of benzene, naphthalene, and formaldehyde independent of the level of background humidity is possible by using shape describing features as input for Linear Discriminant Anal., LDA, or Partial Least Squares - Discriminant Anal., PLS-DA. Leave-one-out cross-validation leads to a correct classification rate of 90% for LDA, and for PLS-DA a classification rate of 83% is achieved. Quantification of naphthalene in the relevant concn. range, i.e., 0-40 ppb, was performed by Partial Least Squares Regression and a combination of LDA with a second order polynomial fit function. The resoln. of the model based on a calibration with three concns. was approx. 8 ppb at 40 ppb naphthalene for both algorithms.Hence, the suggested strategy is suitable for on demand ventilation control in indoor air quality application systems.
- 366Bur, C.; Bastuck, M.; Lloyd Spetz, A.; Andersson, M.; Schütze, A. Selectivity Enhancement of SiC-FET Gas Sensors by Combining Temperature and Gate Bias Cycled Operation Using Multivariate statistics Sens. Actuators, B 2014, 193, 931– 940 DOI: 10.1016/j.snb.2013.12.030Google Scholar366https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2cXps1Gq&md5=1cb066ba9279145de9b4679d7cd1d993Selectivity enhancement of SiC-FET gas sensors by combining temperature and gate bias cycled operation using multivariate statisticsBur, Christian; Bastuck, Manuel; Lloyd Spetz, Anita; Andersson, Mike; Schuetze, AndreasSensors and Actuators, B: Chemical (2014), 193 (), 931-940CODEN: SABCEB; ISSN:0925-4005. (Elsevier B.V.)In this paper temp. modulation and gate bias modulation of a gas sensitive field effect transistor based on silicon carbide (SiC-FET) are combined in order to increase the selectivity. Data evaluation based on extd. features describing the shape of the sensor response was performed using multivariate statistics, here by Linear Discriminant Anal. (LDA). It was found that both temp. cycling and gate bias cycling are suitable for quantification of different concns. of carbon monoxide. However, combination of both approaches enhances the stability of the quantification, resp. the discrimination of the groups in the LDA scatterplot. Feature selection based on the stepwise LDA algorithm as well as selection based on the loadings plot has shown that features both from the temp. cycle and from the bias cycle are equally important for the identification of carbon monoxide, nitrogen dioxide and ammonia. In addn., the presented method allows discrimination of these gases independent of the gas concn. Hence, the selectivity of the FET is enhanced considerably.
- 367Dattoli, E. N.; Davydov, A. V.; Benkstein, K. D. Tin Oxide Nanowire Sensor with Integrated Temperature and Gate Control for Multi-Gas Recognition Nanoscale 2012, 4, 1760– 1769 DOI: 10.1039/c2nr11885hGoogle ScholarThere is no corresponding record for this reference.
- 368Kish, L. B.; Li, Y.; Solis, J. L.; Marlow, W. H.; Vajtai, R.; Granqvist, C. G.; Lantto, V.; Smulko, J. M.; Schmera, G. Detecting Harmful Gases Using Fluctuation-Enhanced Sensing with Taguchi Sensors IEEE Sens. J. 2005, 5, 671– 676 DOI: 10.1109/JSEN.2005.851018Google ScholarThere is no corresponding record for this reference.
- 369Samnakay, R.; Jiang, C.; Rumyantsev, S. L.; Shur, M. S.; Balandin, A. A. Selective Chemical Vapor Sensing with Few-Layer MoS2 Thin-Film Transistors: Comparison with Graphene Devices Appl. Phys. Lett. 2015, 106, 023115 DOI: 10.1063/1.4905694Google Scholar369https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2MXovVyqtQ%253D%253D&md5=ced350a3dc54be040e93fbf351fbfa39Selective chemical vapor sensing with few-layer MoS2 thin-film transistors: Comparison with graphene devicesSamnakay, R.; Jiang, C.; Rumyantsev, S. L.; Shur, M. S.; Balandin, A. A.Applied Physics Letters (2015), 106 (2), 023115/1-023115/5CODEN: APPLAB; ISSN:0003-6951. (American Institute of Physics)We demonstrated selective gas sensing with MoS2 thin-film transistors using the change in the channel conductance, characteristic transient time, and low-frequency current fluctuations as the sensing parameters. The back-gated MoS2 thin-film field-effect transistors were fabricated on Si/SiO2 substrates and intentionally aged for a month to verify reliability and achieve better current stability. The same devices with the channel covered by 10 nm of Al2O3 were used as ref. samples. The exposure to ethanol, acetonitrile, toluene, chloroform, and methanol vapors results in drastic changes in the source-drain current. The current can increase or decrease by more than two-orders of magnitude depending on the polarity of the analyte. The ref. devices with coated channel did not show any response. It was established that transient time of the current change and the normalized spectral d. of the low-frequency current fluctuations can be used as addnl. sensing parameters for selective gas detection with thin-film MoS2 transistors. (c) 2015 American Institute of Physics.
- 370Royer, J. E.; Kappe, E. D.; Zhang, C.; Martin, D. T.; Trogler, W. C.; Kummel, A. C. Organic Thin-Film Transistors for Selective Hydrogen Peroxide and Organic Peroxide Vapor Detection J. Phys. Chem. C 2012, 116, 24566– 24572 DOI: 10.1021/jp306892pGoogle ScholarThere is no corresponding record for this reference.
- 371Shehada, N.; Brönstrup, G.; Funka, K.; Christiansen, S.; Leja, M.; Haick, H. Ultrasensitive Silicon Nanowire for Real-World Gas Sensing: Noninvasive Diagnosis of Cancer from Breath Volatolome Nano Lett. 2015, 15, 1288– 1295 DOI: 10.1021/nl504482tGoogle Scholar371https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2cXitFeitbvK&md5=09e736e8cdd3a04a1b857e579e816d6fUltrasensitive Silicon Nanowire for Real-World Gas Sensing: Noninvasive Diagnosis of Cancer from Breath VolatolomeShehada, Nisreen; Bronstrup, Gerald; Funka, Konrads; Christiansen, Silke; Leja, Marcis; Haick, HossamNano Letters (2015), 15 (2), 1288-1295CODEN: NALEFD; ISSN:1530-6984. (American Chemical Society)The authors report on an ultrasensitive, molecularly modified silicon nanowire field effect transistor that brings together the lock-and-key and cross-reactive sensing worlds for the diagnosis of (gastric) cancer from exhaled volatolome. The sensor is able to selectively detect volatile org. compds. (VOCs) that are linked with gastric cancer conditions in exhaled breath and to discriminate them from environmental VOCs that exist in exhaled breath samples but do not relate to the gastric cancer per se. Using breath samples collected from actual patients with gastric cancer and from volunteers who do not have cancer, blind anal. validated the ability of the reported sensor to discriminate between gastric cancer and control conditions with >85% accuracy, irresp. of important confounding factors such as tobacco consumption and gender. The reported sensing approach paves the way to use the power of silicon nanowires for simple, inexpensive, portable, and noninvasive diagnosis of cancer and other disease conditions.
- 372Milo, C. Ratiometric Oxygen Sensor Compatible with Solid-State Optoelectronics Proc. SPIE 1992, 1796, 360– 363 DOI: 10.1117/12.143552Google ScholarThere is no corresponding record for this reference.
- 373Potyrailo, R. A.; Szumlas, A. W.; Danielson, T. L.; Johnson, M.; Hieftje, G. M. A Dual-Parameter Optical Sensor Fabricated by Gradient Axial Doping of an Optical Fibre Meas. Sci. Technol. 2005, 16, 235– 241 DOI: 10.1088/0957-0233/16/1/031Google Scholar373https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD2MXotVSmtw%253D%253D&md5=40842e5629849df30bd2c2e9c837aeabA dual-parameter optical sensor fabricated by gradient axial doping of an optical fiberPotyrailo, Radislav A.; Szumlas, Andrew W.; Danielson, Timothy L.; Johnson, Michael; Hieftje, Gary M.Measurement Science and Technology (2005), 16 (1), 235-241CODEN: MSTCEP; ISSN:0957-0233. (Institute of Physics Publishing)There is a general need for optical sensors that respond to multiple substances or phys. parameters. Multiple-parameter sensing is not only more efficient, but also permits interacting or interdependent parameters to be individually detd. In this paper, we describe a novel approach to the fabrication of an optical sensor, sensitive to two sep. atm. conditions, but made from a single fiber optic. The optical fiber is drawn from polycarbonate, with a temp.-sensitive phosphor (La2O2S:Eu3+) incorporated directly into the core. Thus, the light-guiding portion of the fiber is responsible for detg. the first parameter of measurement, ambient temp. A thin fiber cladding is subsequently added to the temp.-sensitive core and serves as a chem. sensitive component. This cladding is made from Nafion, and is doped with rhodamine 800. Fluorescence at 750 nm from the rhodamine 800 is shown to be enhanced by the presence of atm. moisture, and is used in conjunction with a ratiometric means of measuring temp. provided by the phosphorescence from the fiber core. This scheme provides a simple and potentially inexpensive way to manuf. fiber-optic sensors capable of multicomponent detns. In addn., the temp.-sensitive core material provides a built-in normalization factor for the temp.-dependent response of the chem. sensitive cladding. The developed dual sensor was evaluated over the temp. range from 20 to 95°C and demonstrated better than 1% relative std. deviation (RSD). The humidity sensor component was evaluated over the range of relative humidity (RH) from 0 to 20% RH over temps. up to 56°C. The detection limits for the humidity sensor were 0.17 and 2.35% RH at 20 and 56°C, resp.
- 374Potyrailo, R. A.; Leach, A. M.; Surman, C. M. Multisize CdSe Nanocrystal/Polymer Nanocomposites for Selective Vapor Detection Identified from High-Throughput Screening Experimentation ACS Comb. Sci. 2012, 14, 170– 178 DOI: 10.1021/co200112sGoogle Scholar374https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC38XhtVylsr8%253D&md5=33f538c2f75eb607872cb5ac2349a6baMultisize CdSe Nanocrystal/Polymer Nanocomposites for Selective Vapor Detection Identified from High-Throughput Screening ExperimentationPotyrailo, Radislav A.; Leach, Andrew M.; Surman, Cheryl M.ACS Combinatorial Science (2012), 14 (3), 170-178CODEN: ACSCCC; ISSN:2156-8944. (American Chemical Society)The authors have implemented high-throughput spectroscopic screening tools for the study of vapor-selectivity of CdSe semiconductor nanocrystals of different size (2.8- and 5.6-nm diam.) upon their incorporation in a library of rationally selected polymeric matrixes. This library of resulting sensing materials was exposed to polar and nonpolar vapors in air. Each of the sensing materials demonstrated its own photoluminescence vapor-response patterns. Two criteria for the evaluation of vapor responses of the library of sensing materials included the diversity and the magnitude of sensing responses. The authors found several polymer matrixes that simultaneously meet these criteria. The authors' new sensing materials based on polymer-embedded semiconductor nanocrystal reagents of different size promise to overcome photobleaching and short shelf life limitations of traditional fluorescent org. reagent-based sensing materials.
- 375Wu, P.; Miao, L. N.; Wang, H. F.; Shao, X. G.; Yan, X. P. A Multidimensional Sensing Device for the Discrimination of Proteins Based on Manganese-Doped ZnS Quantum Dots Angew. Chem., Int. Ed. 2011, 50, 8118– 8121 DOI: 10.1002/anie.201101882Google Scholar375https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC3MXms1Sluro%253D&md5=894c989102851a44cef54e636af77c8aA Multidimensional Sensing Device for the Discrimination of Proteins Based on Manganese-Doped ZnS Quantum DotsWu, Peng; Miao, Ling-Ni; Wang, He-Fang; Shao, Xue-Guang; Yan, Xiu-PingAngewandte Chemie, International Edition (2011), 50 (35), 8118-8121, S8118/1-S8118/18CODEN: ACIEF5; ISSN:1433-7851. (Wiley-VCH Verlag GmbH & Co. KGaA)The authors report a multidimensional sensing device based on simultaneous utilization of the triple-channel optical properties (fluorescent, phosphorescent, and light scattering) of Mn-doped ZnS quantum dots (QDs) for the discrimination of proteins in a "lab-on-a-nanoparticle" approach. The changes in such triple-channel optical properties of Mn-ZnS QDs after interaction with proteins lead to distinct patterns related to each specific protein, which can be incorporated into a new protein sensor array with a single sensor unit in a "lab-on-a-nanoparticle" manner. Application of principal component anal. to the triple-channel optical properties of Mn-ZnS QDs allows the identification of proteins even in the presence of a biol. matrix in a rapid and efficient fashion. The authors regard this QD-based triple-channel sensing system as a preliminary step for further exploration and application of the lab-on-a-nanoparticle concept.
- 376Chen, K.; Shu, Q.; Schmittel, M. Design Strategies for Lab-on-a-Molecule Probes and Orthogonal Sensing Chem. Soc. Rev. 2015, 44, 136– 160 DOI: 10.1039/C4CS00263FGoogle Scholar376https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2cXhvVemtL%252FL&md5=f6e10e7a450605d8b5f70d0e1d1300afDesign strategies for lab-on-a-molecule probes and orthogonal sensingChen, Kun; Shu, Qinghai; Schmittel, MichaelChemical Society Reviews (2015), 44 (1), 136-160CODEN: CSRVBR; ISSN:0306-0012. (Royal Society of Chemistry)A review. This review highlights the currently exploited working concepts of lab-on-a-mol. probes, with a particular focus on what is required for multianalyte detection and quantification in competitive assays. Both, chemosensor and chemodosimeter approaches are considered. The multifaceted design strategies and the orthogonal protocols are evaluated in order to identify and categorise the successful conceptions and to single out unknown territory and challenges for future work.
- 377Xie, W. Y.; Huang, W. T.; Zhang, J. R.; Luo, H. Q.; Li, N. B. A Triple-Channel Optical Signal Probe for Hg2+ Detection Based on Acridine Orange and Aptamer-Wrapped Gold Nanoparticles J. Mater. Chem. 2012, 22, 11479– 11482 DOI: 10.1039/c2jm31280hGoogle Scholar377https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC38XnsVeqtrY%253D&md5=c6e6d4de30fb35f2c0486865becbb96cA triple-channel optical signal probe for Hg2+ detection based on acridine orange and aptamer-wrapped gold nanoparticlesXie, Wan Yi; Huang, Wei Tao; Zhang, Jian Rong; Luo, Hong Qun; Li, Nian BingJournal of Materials Chemistry (2012), 22 (23), 11479-11482CODEN: JMACEP; ISSN:0959-9428. (Royal Society of Chemistry)A triple-channel optical signal probe was designed for the detection of Hg2+ ions. In the absence of Hg2+, the thymine-rich ssDNA wrapped AuNPs were well dispersed. Thus, the color of the soln. is pink-red; the resonance light scattering (RLS) signal is low; the fluorescence of acridine orange (AO) is powerfully quenched. In the presence of Hg2+, the ssDNA formed a T-Hg2+-T configuration, which produces a color change, RLS signal enhancement, and fluorescence of AO restoration. Under the optimum conditions, the system exhibits a dynamic response range for Hg2+ from 50 nM to 5 μM with a detection limit of 30 nM.
- 378Hu, Z.; Pramanik, S.; Tan, K.; Zheng, C.; Liu, W.; Zhang, X.; Chabal, Y. J.; Li, J. Selective, Sensitive, and Reversible Detection of Vapor-Phase High Explosives Via Two-Dimensional Mapping: A New Strategy for MOF-Based Sensors Cryst. Growth Des. 2013, 13, 4204– 4207 DOI: 10.1021/cg4012185Google Scholar378https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC3sXht12htLnO&md5=b85c9d140185ea2ae7fe1939d378cf7dSelective, Sensitive, and Reversible Detection of Vapor-Phase High Explosives via Two-Dimensional Mapping: A New Strategy for MOF-Based SensorsHu, Zhichao; Pramanik, Sanhita; Tan, Kui; Zheng, Chong; Liu, Wei; Zhang, Xiao; Chabal, Yves J.; Li, JingCrystal Growth & Design (2013), 13 (10), 4204-4207CODEN: CGDEFU; ISSN:1528-7483. (American Chemical Society)A new strategy is developed for the effective detection of high explosives in vapor phase by fluorescent metal-org. framework (MOF) sensors. Two structurally related and dynamic MOFs, (Zn)2(ndc)2P·xG [ndc = 2,6-naphthalenedicarboxylate; P = 1,2-bis-(4-pyridyl)-ethane (bpe) or 1,2-bis-(4-pyridyl)-ethylene (bpee); G = guest/solvent mol.], exhibit a two-dimensional signal response toward analytes of interest in the vapor phase, including arom. and aliph. high explosives (e.g., TNT and RDX). The interaction between analytes and the MOF is studied using in situ IR absorption spectroscopy and a DFT computational method.
- 379Lu, Y.; Kong, H.; Wen, F.; Zhang, S.; Zhang, X. Lab-on-Graphene: Graphene Oxide as a Triple-Channel Sensing Device for Protein Discrimination Chem. Commun. 2013, 49, 81– 83 DOI: 10.1039/C2CC37293BGoogle Scholar379https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC38XhslCntrbO&md5=fd32da5fcdd7eb222c5d3330c8365b0eLab-on-graphene: graphene oxide as a triple-channel sensing device for protein discriminationLu, Yuexiang; Kong, Hao; Wen, Fang; Zhang, Sichun; Zhang, XinrongChemical Communications (Cambridge, United Kingdom) (2013), 49 (1), 81-83CODEN: CHCOFS; ISSN:1359-7345. (Royal Society of Chemistry)The fluorescence, catalytic activity and assembly behavior of GO could be simultaneously changed after interaction with proteins, leading to distinct response patterns related to each specific protein. Based on the phenomenon, a triple-channel optical sensor has been proposed in the present communication for protein discrimination with GO as a single sensing element.
- 380Sang, L. J.; Wu, Y. Y.; Wang, H. F. Polyethyleneimine/Manganese-Doped ZnS Nanocomposites: A Multifunctional Probe for Two-Color Imaging and Three-Dimensional Sensing ChemPlusChem 2013, 78, 423– 429 DOI: 10.1002/cplu.201300049Google ScholarThere is no corresponding record for this reference.
- 381Sun, T. Y.; Zhang, D. Q.; Yu, X. F.; Xiang, Y.; Luo, M.; Wang, J. H.; Tan, G. L.; Wang, Q. Q.; Chu, P. K. Dual-Emitting Nanocomposites Derived from Rare-Earth Compound Nanotubes for Ratiometric Fluorescence Sensing Applications Nanoscale 2013, 5, 1629– 1637 DOI: 10.1039/c2nr33217eGoogle Scholar381https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC3sXhvFGltLk%253D&md5=dbe76afb46187dcec2b9ba214dfbe5f3Dual-emitting nanocomposites derived from rare-earth compound nanotubes for ratiometric fluorescence sensing applicationsSun, Tian-Ying; Zhang, Da-Quan; Yu, Xue-Feng; Xiang, Yang; Luo, Min; Wang, Jia-Hong; Tan, Guo-Long; Wang, Qu-Quan; Chu, Paul K.Nanoscale (2013), 5 (4), 1629-1637CODEN: NANOHL; ISSN:2040-3372. (Royal Society of Chemistry)A new class of ratiometric fluorescence sensors composed of rare-earth (RE) compd. nanotubes is described. Polyethylenimine-coated Y hydroxide fluoride nanotubes (YHF NTs) that were synthesized hydrothermally exhibit highly efficient fluorescence when doped with RE ions. The polyethylenimine on the NTs facilitates the incorporation of phosphors such as quantum dots or org. dyes onto the NT surface to produce dual-emitting nanocomposites which are excellent ratiometric fluorescence sensors. The phosphor layer and underlying tubes in the nanocomposites act as the indicator and ref. probes, resp. This ratiometric fluorescence method which can be applied to the detection of heavy metals in solns., temp. sensing, and pH sensing boasts high sensitivity and selectivity as well as better accuracy than traditional intensity-based fluorescence methods.
- 382Chen, K.; Schmittel, M. A Triple-Channel Lab-on-a-Molecule for Triple-Anion Quantification Using an Iridium(III)-Imidazolium Conjugate Chem. Commun. 2014, 50, 5756– 5759 DOI: 10.1039/C4CC01421AGoogle Scholar382https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2cXntlSrs7k%253D&md5=aa5a08cf1836e3e89b63ca44fe050d64A triple-channel lab-on-a-molecule for triple-anion quantification using an iridium(III)-imidazolium conjugateChen, Kun; Schmittel, MichaelChemical Communications (Cambridge, United Kingdom) (2014), 50 (43), 5756-5759CODEN: CHCOFS; ISSN:1359-7345. (Royal Society of Chemistry)A lab-on-a-mol., based on the iridium(III)-imidazolium conjugate 1, allows competitive quantification of three distinct anions in a mixt. using three interrogation channels: F- is detected and quantified via UV-visible, H2PO4- using photoluminescence and AcO- using electrochemiluminescence.
- 383Liu, H.; Fang, G.; Deng, Q.; Wang, S. A Triple-Dimensional Sensing Chip for Discrimination of Eight Antioxidants Based on Quantum Dots and Graphene Biosens. Bioelectron. 2015, 74, 313– 317 DOI: 10.1016/j.bios.2015.04.096Google Scholar383https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2MXhtlymtLbM&md5=4cd1a4c09611216779d8b41501841314A triple-dimensional sensing chip for discrimination of eight antioxidants based on quantum dots and grapheneLiu, Huilin; Fang, Guozhen; Deng, Qiliang; Wang, ShuoBiosensors & Bioelectronics (2015), 74 (), 313-317CODEN: BBIOE4; ISSN:0956-5663. (Elsevier B.V.)A triple-dimensional sensing chip is developed based on simultaneous utilization of fluorescence (FL), electrochem. (ECL) and mass-sensitivity (MS) properties of a novel nanocomposites. The sensing nanomaterial is composed of CdSe/ZnS quantum dots (QDs) and graphene through a one-pot room-temp. reverse microemulsion polymn. Here, full integration of QDs and graphene on one chip provides triple-dimensional sensing signals. It enables quick and accurate discrimination of eight analytes in a "lab-on-a-nanomaterial" approach and notably improves the overall sensor performance. Unknown samples randomly taken from the training set at concns. of 0.7 μM are successfully classified by principal component anal. (PCA) with accuracies of 92.5%, compared with the high performance liq. chromatog. (HPLC) method. We further apply it to discriminate eight antioxidants from real oil samples, and explore the mechanism.
- 384Chen, K.-J.; Lu, C.-J. A Vapor Sensor Array Using Multiple Localized Surface Plasmon Resonance Bands in a Single UV-Vis Spectrum Talanta 2010, 81, 1670– 1675 DOI: 10.1016/j.talanta.2010.03.023Google ScholarThere is no corresponding record for this reference.
- 385Joy, N. A.; Rogers, P. H.; Nandasiri, M. I.; Thevuthasan, S.; Carpenter, M. A. Plasmonic-Based Sensing Using an Array of Au-Metal Oxide Thin Films Anal. Chem. 2012, 84, 10437– 10444 DOI: 10.1021/ac3026477Google Scholar385https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC38Xhs1entrzE&md5=43a3897944a5dbddee3b92351823ccd4Plasmonic-based sensing using an array of Au-metal oxide thin filmsJoy, Nicholas A.; Rogers, Phillip H.; Nandasiri, Manjula I.; Thevuthasan, Suntharampillai; Carpenter, Michael A.Analytical Chemistry (Washington, DC, United States) (2012), 84 (23), 10437-10444CODEN: ANCHAM; ISSN:0003-2700. (American Chemical Society)An optical plasmonic-based sensing array was developed and tested for the selective and sensitive detection of H2, CO, and NO2 at a temp. of 500°C in an oxygen-contg. background. The three-element sensing array used Au nanoparticles embedded in sep. thin films of yttria-stabilized zirconia (YSZ), CeO2, and TiO2. A peak in the absorbance spectrum due to a localized surface plasmon resonance (LSPR) on the Au nanoparticles was monitored for each film during gas exposures and showed a blue shift in the peak positions for the reducing gases, H2 and CO, and a red shift for the oxidizing gas, NO2. A more in-depth look at the sensing response was performed using the multivariate methods of principal component anal. (PCA) and linear discriminant anal. (LDA) on data from across the entire absorbance spectrum range. Qual. results from both methods showed good sepn. between the three analytes for both the full array and the Au-TiO2 sample. Quantification of LDA cluster sepn. using the Mahalanobis distance showed better cluster sepn. for the array, but there were some instances with the lowest concns. where the single Au-TiO2 film had sepn. better than that of the array. A 2nd method to quantify cluster sepn. in LDA space was developed using multidimensional vol. anal. of the individual cluster vol., overlapped cluster vol., and empty vol. between clusters. Compared to the individual sensing elements, the array showed less cluster overlap, smaller cluster vols., and more space between clusters, all of which were expected for improved separability between the analytes.
- 386Scholten, K.; Reddy, K.; Fan, X.; Zellers, E. T. Vapor Discrimination by Dual-Laser Reflectance Sensing of a Single Functionalized Nanoparticle Film Anal. Methods 2013, 5, 4268– 4272 DOI: 10.1039/c3ay40952jGoogle Scholar386https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC3sXhtF2qsLnF&md5=7d2251b83492371327cc1643bf3baa5dVapor discrimination by dual-laser reflectance sensing of a single functionalized nanoparticle filmScholten, Kee; Reddy, Karthik; Fan, Xudong; Zellers, Edward T.Analytical Methods (2013), 5 (16), 4268-4272CODEN: AMNEGX; ISSN:1759-9679. (Royal Society of Chemistry)Sorption-induced changes in the localized surface-plasmon resonance (LSPR) of an n-octanethiolate-monolayer-protected gold nanoparticle film on a Si chip are exploited to differentiate two volatile org. compds. (VOC) with a single sensor. Probing the film with 488 nm and 785 nm lasers gave reflectance sensitivity ratios at the two wavelengths of 0.68 and 0.80 for toluene and n-heptane, resp., permitting their discrimination. Swelling-induced increases in inter-particle distance appear to predominate over changes in the refractive index of the inter-particle matrix in the sensor responses. The corresponding ratios of sensitivities with a ref. film of polydimethylsiloxane did not differ for the two vapors. Approaches for extending the capability for VOC discrimination by use of arrays of such LSPR sensors are discussed, along with the advantages of employing this simple platform in compact, field-deployable environmental VOC monitoring systems.
- 387Karker, N.; Dharmalingam, G.; Carpenter, M. A. Thermal Energy Harvesting Plasmonic Based Chemical Sensors ACS Nano 2014, 8, 10953– 10962 DOI: 10.1021/nn504870bGoogle ScholarThere is no corresponding record for this reference.
- 388Buso, D.; Guglielmi, M.; Martucci, A.; Mattei, G.; Mazzoldi, P.; Sada, C.; Post, M. L. Growth of Cookie-Like Au/NiO Nanoparticles in SiO2 Sol-Gel Films and Their Optical Gas Sensing Properties Cryst. Growth Des. 2008, 8, 744– 749 DOI: 10.1021/cg700816nGoogle Scholar388https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD1cXitFaruw%253D%253D&md5=13c1482b639c76f4c0bcefc298cae50eGrowth of Cookie-like Au/NiO Nanoparticles in SiO2 Sol-Gel Films and Their Optical Gas Sensing PropertiesBuso, Dario; Guglielmi, Massimo; Martucci, Alessandro; Mattei, Giovanni; Mazzoldi, Paolo; Sada, Cinzia; Post, Michael L.Crystal Growth & Design (2008), 8 (2), 744-749CODEN: CGDEFU; ISSN:1528-7483. (American Chemical Society)The favorable lattice matching between Au and NiO crystals made possible the growth of unique cookie-like nanoparticles (25 nm mean diam.) inside a porous SiO2 film by simply tailoring the film synthesis parameters. The unusual aggregates result from the coupling of well distinguishable Au and NiO hemispheres, which resp. face each other through the (100) and (200) lattice planes. High resoln. TEM anal. revealed that the 2-fold nanostructures show a sharp flat interface with epitaxial coherence between the Au and NiO phases. The surface plasmon resonance (SPR) bands obsd. in optical absorption spectra provides evidence for the effect of the atypical dielec. nature of the media surrounding the Au aggregates. The films show noticeable and reversible change in the optical transmittance when exposed to CO and H2, with different features according to the detected species. The presence of CO does not modify the max. SPR band wavelength, while H2 induces a clear shift of the overall plasmonic resonance frequencies.
- 389Larsson, E. M.; Langhammer, C.; Zorić, I.; Kasemo, B. Nanoplasmonic Probes of Catalytic Reactions Science 2009, 326, 1091– 1094 DOI: 10.1126/science.1176593Google Scholar389https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD1MXhsVentLvM&md5=90aed23a42f92e27b1a2592e4384fa77Nanoplasmonic Probes of Catalytic ReactionsLarsson, Elin M.; Langhammer, Christoph; Zoric, Igor; Kasemo, BengtScience (Washington, DC, United States) (2009), 326 (5956), 1091-1094CODEN: SCIEAS; ISSN:0036-8075. (American Association for the Advancement of Science)Optical probes of heterogeneous catalytic reactions can be valuable tools for optimization and process control because they can operate under realistic conditions, but often probes lack sensitivity. We have developed a plasmonic sensing method for such reactions based on arrays of nanofabricated gold disks, covered by a thin (~10 nm) coating (catalyst support) on which the catalyst nanoparticles are deposited. The sensing particles monitor changes in surface coverage of reactants during catalytic reaction through peak shifts in the optical extinction spectrum. Sensitivities to below 10-3 monolayers are estd. The capacity of the method is demonstrated for three catalytic reactions, CO and H2 oxidn. on Pt, and NOx conversion to N2 on Pt/BaO.
- 390Della Gaspera, E.; Guglielmi, M.; Agnoli, S.; Granozzi, G.; Post, M. L.; Bello, V.; Mattei, G.; Martucci, A. Au Nanoparticles in Nanocrystalline TiO2-NiO Films for SPR-Based, Selective H2S Gas Sensing Chem. Mater. 2010, 22, 3407– 3417 DOI: 10.1021/cm100297qGoogle Scholar390https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC3cXlvValu7g%253D&md5=04ec9c93266e11844140d4b9180cd610Au Nanoparticles in Nanocrystalline TiO2-NiO Films for SPR-Based, Selective H2S Gas SensingDella Gaspera, Enrico; Guglielmi, Massimo; Agnoli, Stefano; Granozzi, Gaetano; Post, Michael L.; Bello, Valentina; Mattei, Giovanni; Martucci, AlessandroChemistry of Materials (2010), 22 (11), 3407-3417CODEN: CMATEX; ISSN:0897-4756. (American Chemical Society)Thin films composed of Au nanoparticles dispersed inside a TiO2-NiO mixed oxide matrix were prepd. by the sol-gel method, resulting in nanostructured composites with a morphol. and crystallinity that depend on synthesis parameters and thermal treatment. Their functional activity as H2S optical sensors is due to Au-localized surface plasmon resonance (SPR) which is reversible. The detection sensitivity is down to a few ppm of H2S, and almost no interference in response is obsd. during simultaneous exposure to CO or H2, resulting in a highly sensitive and selective sensor for H2S detection. For mechanistic studies, exptl. evidence using reaction product anal. and thin film surface characterization suggests a direct catalytic oxidn. of H2S over the Au-TiO2-NiO nanocomposite film.
- 391Ohodnicki, P. R.; Wang, C.; Natesakhawat, S.; Baltrus, J. P.; Brown, T. D. In-Situ and Ex-Situ Characterization of TiO2 and Au Nanoparticle Incorporated TiO2 Thin Films for Optical Gas Sensing at Extreme Temperatures J. Appl. Phys. 2012, 111, 064320 DOI: 10.1063/1.3695380Google Scholar391https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC38Xks1CltL0%253D&md5=96cdab2ae8f2c760a97b05f147058ed3In-situ and ex-situ characterization of TiO2 and Au nanoparticle incorporated TiO2 thin films for optical gas sensing at extreme temperaturesOhodnicki, Paul R., Jr.; Wang, Congjun; Natesakhawat, Sittichai; Baltrus, John P.; Brown, Thomas D.Journal of Applied Physics (2012), 111 (6), 064320/1-064320/11CODEN: JAPIAU; ISSN:0021-8979. (American Institute of Physics)Sensor technologies that can operate under extreme conditions including high temps., high pressures, highly reducing and oxidizing environments, and corrosive gases are needed for process monitoring and control in advanced fossil energy applications. Sensor technologies based on optical waveguide-based techniques are highly attractive for passive, embedded, and remote sensing. A crit. enabling technol. for optical waveguide sensors is the development of advanced optical thin film coatings which have a desired set of optical properties that change in a rapid, selective, and sensitive manner to a particular quantity of interest. TiO2 and Au nanoparticle incorporated TiO2 nanocomposite thin films were prepd. through sol-gel deposition techniques and their resp. optical responses to a 4% H2/N2 mixt. were studied in the visible / near-IR range of 400-1000 nm. A tendency for Au nanoparticles to occupy special sites on the TiO2 microstructure, such as grain boundaries, twin boundaries, and triple points is rationalized in terms of basic surface energy arguments. The Au / TiO2 nanocomposite films showed a useful optical response due to a reversible, rapid, and repeatable shift in the localized surface plasma resonance peak of Au nanoparticles at a temp. of 650° and 850°. But high temp. exposure of TiO2 films to reducing gases at 850° resulted in the growth of abnormally large grains or hillocks that protruded from the sample surface and resulted in light scattering and an irreversible decrease in transmission at short wavelengths. The origin of the obsd. optical response of Au / TiO2 nanocomposite films is discussed in the context of work by prior investigators in the Au / yttria-stabilized Zirconia (YSZ) system and needs for future research in this area is highlighted. (c) 2012 American Institute of Physics.
- 392Della Gaspera, E.; Guglielmi, M.; Perotto, G.; Agnoli, S.; Granozzi, G.; Post, M. L.; Martucci, A. CO Optical Sensing Properties of Nanocrystalline ZnO-Au Films: Effect of Doping with Transition Metal Ions Sens. Actuators, B 2012, 161, 675– 683 DOI: 10.1016/j.snb.2011.11.011Google Scholar392https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC38XhtFCjtLs%253D&md5=834ef8d19bcafc4639dfe9bbd3e6cc93CO optical sensing properties of nanocrystalline ZnO-Au films: Effect of doping with transition metal ionsDella Gaspera, E.; Guglielmi, M.; Perotto, G.; Agnoli, S.; Granozzi, G.; Post, M. L.; Martucci, A.Sensors and Actuators, B: Chemical (2012), 161 (1), 675-683CODEN: SABCEB; ISSN:0925-4005. (Elsevier B.V.)ZnO nanocrystals, pure and doped with transition metal ions, were prepd. using colloidal techniques; after purifn. and concn. protocols, the ZnO solns. are mixed with monodisperse Au colloidal suspensions and used for thin film depositions. The effect of the dopant ions on the structural, morphol. and optical properties of the as-prepd. colloids as well as the nanocomposite thin films was analyzed and discussed. The dopant presence was found to affect the CO optical sensing properties of the nanocomposite ZnO-Au films: compared to pure ZnO, an increase in sensitivity ≤80 and 55% was detected for Co-doped and Mn-doped ZnO resp., while Ni-doped ZnO films show only minor improvements. This observation was ascribed to the multiple oxidn. states of Co and Mn ions that can facilitate electron transfer between the target gas and semiconductive oxide matrix, and also to the lower surface concn. of Ni ions inside ZnO crystals, as compared to Co and Mn. A fast and reversible response after repeated CO exposures was detected for all tested samples, and a linear response intensity with the order of magnitude of CO concn. was obsd. in the 10-10,000 ppm range, with a lower detection limit of 1-2 ppm.
- 393Ohodnicki, P. R.; Baltrus, J. P.; Brown, T. D. Pd/SiO2 and AuPd/SiO2 Nanocomposite-Based Optical Fiber Sensors for H2 Sensing Applications Sens. Actuators, B 2015, 214, 159– 168 DOI: 10.1016/j.snb.2015.02.076Google Scholar393https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2MXksVCksrw%253D&md5=8dbbabab33737210ffda99ff4ecc1fe2Pd/SiO2 and AuPd/SiO2 nanocomposite-based optical fiber sensors for H2 sensing applicationsOhodnicki, P. R.; Baltrus, J. P.; Brown, T. D.Sensors and Actuators, B: Chemical (2015), 214 (), 159-168CODEN: SABCEB; ISSN:0925-4005. (Elsevier B.V.)The ability to accurately and safely monitor hydrogen concn. is of significant importance for a broad range of energy, defense, aviation, and aerospace applications with one of the most notable applications being leak detection for hydrogen above the lower explosive limit. Optical-based approaches offer significant safety advantages as compared to elec.-based sensors and Pd or AuPd-alloys are commonly utilized as the functional sensor layer due to a well-known, characteristic, and selective interaction with H2. In this work, optical fiber-based sensors comprised of Pd and AuPd alloy nanoparticle incorporated SiO2 thin films deposited onto unclad multimode silica-based optical fiber evanescent wave absorption spectroscopy sensing elements have been investigated. Selective, sensitive, and monotonic H2 sensing responses have been demonstrated at levels significantly greater than the lower explosive limit in the presence of CO and O2 near room temp. A tendency for partial oxidn. of the noble metal nanoparticles upon exposure to oxidizing atmospheres is confirmed directly through XPS, particularly at elevated temps. Monotonic H2 sensing responses are also obsd. at elevated temps. in cases where oxygen is not introduced into the atm. However, more complex sensing responses in multi-component elevated temp. gas streams contg. oxidizing and reducing species can be obsd. which likely result from oxidn. and redn. of noble metal nanoparticles. These results demonstrate that the incorporation of noble metals such as Pd and Pd-alloy nanoparticles into inert dielec. matrixes such as SiO2 can impart new optical sensing functionality potentially useful for H2 sensing applications.
- 394Wadell, C.; Syrenova, S.; Langhammer, C. Plasmonic Hydrogen Sensing with Nanostructured Metal Hydrides ACS Nano 2014, 8, 11925– 11940 DOI: 10.1021/nn505804fGoogle Scholar394https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2cXhvF2hsLvE&md5=d993499d5b10ba36aef1c5b8d2953693Plasmonic Hydrogen Sensing with Nanostructured Metal HydridesWadell, Carl; Syrenova, Svetlana; Langhammer, ChristophACS Nano (2014), 8 (12), 11925-11940CODEN: ANCAC3; ISSN:1936-0851. (American Chemical Society)A review. In this review, the evolution of localized surface plasmon resonance and surface plasmon resonance hydrogen sensors based on nanostructured metal hydrides, which has accelerated significantly during the past 5 years are discussed. The authors put particular focus on how, conceptually, plasmonic resonances can be used to study metal-hydrogen interactions at the nanoscale, both at the ensemble and at the single-nanoparticle level. Such efforts are motivated by a fundamental interest in understanding the role of nanosizing on metal hydride formation processes in the quest to develop efficient solid-state hydrogen storage materials with fast response times, reasonable thermodn., and acceptable long-term stability. Therefore, a brief introduction to the thermodn. of metal hydride formation is also given. However, plasmonic hydrogen sensors not only are of academic interest as research tool in materials science but also are predicted to find more practical use as all-optical gas detectors in industrial and medical applications, as well as in a future hydrogen economy, where hydrogen is used as a carbon free energy carrier. Therefore, the wide range of different plasmonic hydrogen sensor designs already available is reviewed together with theor. efforts to understand their fundamentals and optimize their performance in terms of sensitivity. In this context, the authors also highlight important challenges to be addressed in the future to take plasmonic hydrogen sensors from the lab. to real applications in devices, including poisoning/deactivation of the active materials, sensor lifetime, and cross-sensitivity toward other gas species.
- 395Lindquist, N. C.; Turner, M. A.; Heppner, B. P. Template Fabricated Plasmonic Nanoholes on Analyte-Sensitive Substrates for Real-Time Vapor Sensing RSC Adv. 2014, 4, 15115– 15121 DOI: 10.1039/c4ra01797hGoogle Scholar395https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2cXkvFyrurs%253D&md5=d70b167b620176e15c884534567cafb2Template fabricated plasmonic nanoholes on analyte-sensitive substrates for real-time vapor sensingLindquist, Nathan C.; Turner, Mark A.; Heppner, Benjamin P.RSC Advances (2014), 4 (29), 15115-15121CODEN: RSCACL; ISSN:2046-2069. (Royal Society of Chemistry)Sensing with nanostructured plasmonic devices has become an important research field due to their proven ability to be extremely sensitive, compact, multiplexed, and compatible with low-cost fabrication techniques. In this paper, we employ a modified template stripping method to produce plasmonic nanohole arrays on analyte-sensitive substrates for real-time vapor sensing. The device operates by exploiting simultaneous plasmonic resonances within the substrate as well as within the vapor being tested. Because the substrate is in contact with vapor due to the open-hole geometry, red-shifts (air-side resonances) and blue-shifts (substrate-side resonances) are seen at the same time during exposure to <10 ppm ethanol vapor in nitrogen. We also show neg. control expts. with similar concns. of m-xylene, as well as multiplex sensing potential with chem. patterned substrates. Our devices could operate as low-cost gas sensors for environmental monitoring, security, or food safety.
- 396Mishra, S. K.; Tripathi, S. N.; Choudhary, V.; Gupta, B. D. Surface Plasmon Resonance-Based Fiber Optic Methane Gas Sensor Utilizing Graphene-Carbon Nanotubes-Poly(Methyl Methacrylate) Hybrid Nanocomposite Plasmonics 2015, 10, 1147– 1157 DOI: 10.1007/s11468-015-9914-5Google Scholar396https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2MXktlGmtbo%253D&md5=a89e3e429be74da096735e4fc83a1358Surface Plasmon Resonance-Based Fiber Optic Methane Gas Sensor Utilizing Graphene-Carbon Nanotubes-Poly(Methyl Methacrylate) Hybrid NanocompositeMishra, Satyendra K.; Tripathi, Sandeep N.; Choudhary, Veena; Gupta, Banshi D.Plasmonics (2015), 10 (5), 1147-1157CODEN: PLASCS; ISSN:1557-1955. (Springer)Fabrication and characterization of a surface plasmon resonance (SPR)-based fiber optic sensor using graphene-carbon nanotubes/poly(Me methacrylate) (GCNT/PMMA) hybrid composites for the detection of methane gas have been carried out. Four kinds of probes with different over-layers on the silver-coated unclad core of the fiber have been fabricated to achieve the best performance of the sensor. The over-layers used are of reduced graphene oxide (rGO), carbon nanotubes (CNT), reduced graphene oxide-carbon nanotubes (GCNT), and GCNT/PMMA hybrid nanocomposite. The sensing ability of all the probes has been tested for the following gases: methane, ammonia, hydrogen sulfide, chlorine, carbon dioxide, hydrogen, and nitrogen. The SPR spectra of all the probes for different concns. of gases have been detd. A red shift in the resonance wavelength has been obsd. with increasing concn. of gases around the probes. Out of all the probes, the one with GCNT/PMMA hybrid nanocomposite over-layer has been found to be highly selective towards methane gas. For max. sensitivity, the performance of the probe has been evaluated using different doping concns. of GCNT in GCNT/PMMA nanocomposite. The doping concn. of 5 wt.% has been found to give max. sensitivity of the sensor. Since the probe has been fabricated on optical fiber, apart from high selectivity and sensitivity, it has addnl. advantages such as miniaturized probe, low cost, capability of online monitoring and remote sensing, and immunity to electromagnetic field interference.
- 397Xie, Z.; Cao, K.; Zhao, Y.; Bai, L.; Gu, H.; Xu, H.; Gu, Z. Z. An Optical Nose Chip Based on Mesoporous Colloidal Photonic Crystal Beads Adv. Mater. 2014, 26, 2413– 2418 DOI: 10.1002/adma.201304775Google Scholar397https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC3sXhvFOmurnF&md5=0f29ee69e8e08754277714e3436fd0aaAn Optical Nose Chip Based on Mesoporous Colloidal Photonic Crystal BeadsXie, Zhuoying; Cao, Kaidi; Zhao, Yuanjin; Bai, Lin; Gu, Hongcheng; Xu, Hua; Gu, Zhong-ZeAdvanced Materials (Weinheim, Germany) (2014), 26 (15), 2413-2418CODEN: ADVMEW; ISSN:0935-9648. (Wiley-VCH Verlag GmbH & Co. KGaA)We designed and prepd. a novel optical nose chip by using surface functionalized mesoporous colloidal photonic crystal beads.
- 398Zhang, Y.; Qiu, J.; Hu, R.; Li, P.; Gao, L.; Heng, L.; Tang, B. Z.; Jiang, L. A Visual and Organic Vapor Sensitive Photonic Crystal Sensor Consisting of Polymer-Infiltrated SiO2 Inverse Opal Phys. Chem. Chem. Phys. 2015, 17, 9651– 9658 DOI: 10.1039/C4CP06019AGoogle Scholar398https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2MXjvF2lsbs%253D&md5=c4aea2d8e1af18c9656c4b326bc9e96cA visual and organic vapor sensitive photonic crystal sensor consisting of polymer-infiltrated SiO2 inverse opalZhang, Yuqi; Qiu, Jianhua; Hu, Rongrong; Li, Pei; Gao, Loujun; Heng, Liping; Tang, Ben Zhong; Jiang, LeiPhysical Chemistry Chemical Physics (2015), 17 (15), 9651-9658CODEN: PPCPFQ; ISSN:1463-9076. (Royal Society of Chemistry)A photonic crystal (PC) sensor that can selectively detect org. vapors through visual color changes has been proposed. The sensor was fabricated by infiltrating a tetraphenylethene polymer (TPEP) into the voids of SiO2 inverse opal photonic crystal. When the sensor was exposed to THF or acetone vapor, a red shift of the stopband of more than 50 nm could be clearly obsd.; meanwhile, the film's color changed from violet to cyan. Subsequently, when exposed to air, the stopband underwent a blue shift and the color returned to violet. The reason for the obsd. change is that a reversible adsorption-desorption process occurs on alternate exposure of the sensor to org. vapor and air, due to the high sp. surface area of the inverse opal macroporous structure and the high affinity of TPEP to THF and acetone. The adsorption of vapor analyte can increase the PC's effective refractive index, which will induce the stopband red shift and the resulting color change according to Bragg's Law. The reversible adsorption-desorption of org. vapors varied the effective refractive index of the sensor repeatedly, causing the reversible stopband shift and color change, and providing a general method for the design of visual vapor sensors.
- 399Gao, J.; Gao, T.; Sailor, M. J. Porous-Silicon Vapor Sensor Based on Laser Interferometry Appl. Phys. Lett. 2000, 77, 901– 903 DOI: 10.1063/1.1306640Google Scholar399https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD3cXlsVWnu7g%253D&md5=1f6c3081bbdb52ac6f2c2cdfbaa68461Porous-silicon vapor sensor based on laser interferometryGao, Jun; Gao, Ting; Sailor, Michael J.Applied Physics Letters (2000), 77 (6), 901-903CODEN: APPLAB; ISSN:0003-6951. (American Institute of Physics)Certain porous-Si (PS) films exhibit well-resolved Fabry-Perot fringes in their optical reflection spectra due to thin-film interference. The fringes shift to higher wavelengths when the PS is exposed to vapors from org. solvents, as a result of an increase in the av. refractive index of the PS layer. If a small diode laser was used as the light source, the shift of the Fabry-Perot fringes upon analyte adsorption results in a change in the reflected light intensity, which correlates with the concn. of the analyte (EtOH) in an air stream. Based on this principle, a PS vapor sensor was demonstrated with a detection limit of 500 ppb and a dynamic range of nearly five orders of magnitude.
- 400Sailor, M. J. Color Me Sensitive: Amplification and Discrimination in Photonic Silicon Nanostructures ACS Nano 2007, 1, 248– 252 DOI: 10.1021/nn700340uGoogle Scholar400https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD2sXhtlKgtrjN&md5=e764d9c54b6e960d39a454bd4820d10dColor Me Sensitive: Amplification and Discrimination in Photonic Silicon NanostructuresSailor, Michael J.ACS Nano (2007), 1 (4), 248-252CODEN: ANCAC3; ISSN:1936-0851. (American Chemical Society)A review perspective. A new paper by K. Kilian et al. (ibid. 355-361) in this issue discusses some of the considerations for fabrication of biosensor devices in the porous silicon material system. The results focus on optical detection of protease activity on specific substrates that have been immobilized in a porous silicon matrix. Solns. to important limitations of porous microsensors are presented: stabilizing the sensor against corrosion-induced zero point drift, minimizing the effects of nonspecific protein binding, and enhancing the optical response by incorporation of a catalytic reaction in the sensing scheme.
- 401Zhao, Y.; Xie, Z.; Gu, H.; Zhu, C.; Gu, Z. Bio-Inspired Variable Structural Color Materials Chem. Soc. Rev. 2012, 41, 3297– 3317 DOI: 10.1039/c2cs15267cGoogle Scholar401https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC38XksVOhu78%253D&md5=5503c2dd365da49de07c0557d6645835Bio-inspired variable structural color materialsZhao, Yuanjin; Xie, Zhuoying; Gu, Hongcheng; Zhu, Cun; Gu, ZhongzeChemical Society Reviews (2012), 41 (8), 3297-3317CODEN: CSRVBR; ISSN:0306-0012. (Royal Society of Chemistry)A review. Natural structural color materials, esp. those that can undergo reversible changes, are attracting increasing interest in a wide variety of research fields. Inspired by the natural creatures, many elaborately nanostructured photonic materials with variable structural colors were developed. These materials have found important applications in switches, display devices, sensors, and so on. In this crit. review, we will provide up-to-date research concerning the natural and bio-inspired photonic materials with variable structural colors. After introducing the variable structural colors in natural creatures, we will focus on the studies of artificial variable structural color photonic materials, including their bio-inspired designs, fabrications and applications. The prospects for the future development of these fantastic variable structural color materials will also be presented. We believe this review will promote the communications among biol., bionics, chem., optical physics, and material science (196 refs.).
- 402Xu, H.; Wu, P.; Zhu, C.; Elbaz, A.; Gu, Z. Z. Photonic Crystal for Gas Sensing J. Mater. Chem. C 2013, 1, 6087– 6098 DOI: 10.1039/c3tc30722kGoogle Scholar402https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC3sXhsVaqs7rJ&md5=a423c7f39aca0ab6f244f658e091d749Photonic crystal for gas sensingXu, Hua; Wu, Pin; Zhu, Chu; Elbaz, Abdelrahman; Gu, Zhong ZeJournal of Materials Chemistry C: Materials for Optical and Electronic Devices (2013), 1 (38), 6087-6098CODEN: JMCCCX; ISSN:2050-7534. (Royal Society of Chemistry)A review. Photonic crystal (PhCs) based sensing technol. has gained more and more attention because of its obvious advantages in sensitivity, stability, security, miniaturization, portability, online use and remote monitoring. Many PhC sensors were proposed based on their novel structure and unique optical properties. In this review, the authors will describe the recent progress in the use of natural and artificial PhC materials for gas/vapor sensing, including Morpho butterfly wings and their mimicry of nanostructures, porous silicon, Bragg stacks, colloidal crystals and inverse opal. Here the authors will discuss the PhCs with different structures and their resp. gas sensing properties, focusing on the description of the functional structure of the PhCs materials and their sensing mechanisms.
- 403Burgess, I. B.; Lončar, M.; Aizenberg, J. Structural Colour in Colourimetric Sensors and Indicators J. Mater. Chem. C 2013, 1, 6075– 6086 DOI: 10.1039/c3tc30919cGoogle Scholar403https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC3sXhsVaqs73J&md5=9e161b255e48f329114e9274624215beStructural color in colorimetric sensors and indicatorsBurgess, Ian B.; Loncar, Marko; Aizenberg, JoannaJournal of Materials Chemistry C: Materials for Optical and Electronic Devices (2013), 1 (38), 6075-6086CODEN: JMCCCX; ISSN:2050-7534. (Royal Society of Chemistry)Colorimetric sensors and indicators are widely used because of their low cost and simplicity. A significant challenge assocd. with the design of this type of device is that the sensing mechanism must be simultaneously optimized for the sensitivity of the response and a visually perceptible color change. Structural color, derived from coherent scattering rather than mol. absorption, is a promising route to colorimetric sensor design because color shifts are tied to changes in one of many phys. properties of a material, rather than a specific chem. process. This feature article presents an overview of the development of low-cost sensors and indicators that exploit structural color. Building upon recent advances in structurally adaptive materials design, structural color sensors were developed for a wide variety of previously inaccessible phys. (e.g. temp., strain, elec. fields) and chem. stimuli (e.g. small org. mols., charged species, biomacromols. and metabolites). These devices, often exceeding the state of the art in performance, simplicity or both, have bright prospects for market impact in areas such as environmental monitoring, workplace hazard identification, threat detection, and point-of-care diagnostics. Finding the ideal balance between performance (e.g. sensitivity, specificity, reproducibility, etc.) and simplicity (e.g. colorimetric vs. spectroscopic readout) will be one of the most crit. elements in the further development of structural color sensors. This balance should be driven largely by the market demands and competing technologies.
- 404Pacholski, C. Photonic Crystal Sensors Based on Porous Silicon Sensors 2013, 13, 4694– 4713 DOI: 10.3390/s130404694Google Scholar404https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC3sXmtlKju78%253D&md5=a19de52319dd9013974c9df6dd6dfcf3Photonic crystal sensors based on porous siliconPacholski, ClaudiaSensors (2013), 13 (), 4694-4713CODEN: SENSC9; ISSN:1424-8220. (MDPI AG)A review. Porous silicon was established as an excellent sensing platform for the optical detection of hazardous chems. and biomol. interactions such as DNA hybridization, antigen/antibody binding and enzymic reactions. Its porous nature provides a high surface area within a small vol., which can be easily controlled by changing the pore sizes. As the porosity and consequently the refractive index of an etched porous silicon layer depends on the electrochem. etching conditions photonic crystals composed of multilayered porous silicon films with well-resolved and narrow optical reflectivity features can easily be obtained. The prominent optical response of the photonic crystal decreases the detection limit and therefore increases the sensitivity of porous silicon sensors in comparison to sensors utilizing Fabry-Perot-based optical transduction. Development of porous silicon photonic crystal sensors which allow for the detection of analytes by the naked eye using a simple color change or the fabrication of stacked porous silicon photonic crystals showing two distinct optical features which can be utilized for the discrimination of analytes emphasize its high application potential.
- 405Harraz, F. A. Porous Silicon Chemical Sensors and Biosensors: A Review Sens. Actuators, B 2014, 202, 897– 912 DOI: 10.1016/j.snb.2014.06.048Google Scholar405https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2cXht1aktr%252FJ&md5=d6c73662395353bc67679cfbbdadfa82Porous silicon chemical sensors and biosensors: A reviewHarraz, Farid A.Sensors and Actuators, B: Chemical (2014), 202 (), 897-912CODEN: SABCEB; ISSN:0925-4005. (Elsevier B.V.)The use of porous silicon (PSi) as a sensor for detection of various analytes is reviewed. The optical or elec. properties of PSi are key sensing parameters that have been used in many chem. and biol. sensing applications. PSi is a promising candidate due to ease of fabrication, large surface area, various accessible pore sizes and morphologies, controllable surface modification and its compatibility with conventional silicon processing technol. The adsorption of chem. or biol. mols. into the pores modifies the elec. and/or optical properties, allowing convenient and sensitive measurement approach. In this review, we provide a crit. assessment of the development of PSi as a promising material for chem. and biosensing applications. Formation procedures of PSi with various pore sizes and morphologies are firstly given. Surface properties and structural characteristics of the material are briefly described. The recent progress on utilization of such porous structures in chem. and biosensing applications is then addressed in the context of surface chem. effects and nanostructures, measuring approaches, operating concepts and device sensitivity and stability. Finally, concluding remarks with existing challenges that hinder the material for com. use are highlighted.
- 406Wang, F.; Meng, Z.; Xue, F.; Xue, M.; Lu, W.; Chen, W.; Wang, Q.; Wang, Y. Responsive Photonic Crystal for the Sensing of Environmental Pollutants Trends Environ. Anal. Chem. 2014, 3–4, 1– 6 DOI: 10.1016/j.teac.2014.09.002Google Scholar406https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2MXjtFehtLw%253D&md5=b29b5a331c5e6b8da736978f3ce3b855Responsive photonic crystal for the sensing of environmental pollutantsWang, Fengyan; Meng, Zihui; Xue, Fei; Xue, Min; Lu, Wei; Chen, Wei; Wang, Qiuhong; Wang, YifeiTrends in Environmental Analytical Chemistry (2014), 3-4 (), 1-6CODEN: TEACA7; ISSN:2214-1588. (Elsevier B.V.)This review covers the concepts of photonic crystal (PhC) and its usage for the sensing of environmental pollutants. PhCs are composed of periodic and ordered nanostructures which can manipulate the diffraction or reflection of light propagation through the structures. If the light spectra locate in the visible range, the color of materials can be obsd. by naked eye. The optical properties of PhCs are detd. by the lattice const. of the crystal or by the refractive index contrast between the colloids and the surrounding medium. Based on these features, responsive PhCs can be designed to detect the environmental pollutants. In this review, we primarily described the photonic crystals for the sensing of volatile org. compds. (VOCs), organophosphates (OPs), heavy metal ions and endocrine disrupting chems. (EDCs), and these sensors exhibited excellent sensitivity and are promising for the on-site monitoring of pollutants.
- 407Fenzl, C.; Hirsch, T.; Wolfbeis, O. S. Photonic Crystals for Chemical Sensing and Biosensing Angew. Chem., Int. Ed. 2014, 53, 3318– 3335 DOI: 10.1002/anie.201307828Google Scholar407https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2cXhtlejsrw%253D&md5=30aa4b19c3a0b9a863f55aae97d7a90bPhotonic Crystals for Chemical Sensing and BiosensingFenzl, Christoph; Hirsch, Thomas; Wolfbeis, Otto S.Angewandte Chemie, International Edition (2014), 53 (13), 3318-3335CODEN: ACIEF5; ISSN:1433-7851. (Wiley-VCH Verlag GmbH & Co. KGaA)A review. This Review covers photonic crystals (PhCs) and their use for sensing mainly chem. and biochem. parameters, with a particular focus on the materials applied. Specific sections are devoted to (a) a lead-in into natural and synthetic photonic nanoarchitectures, (b) the various kinds of structures of PhCs, (c) reflection and diffraction in PhCs, (d) aspects of sensing based on mech., thermal, optical, elec., magnetic, and purely chem. stimuli, (e) aspects of biosensing based on biomols. incorporated into PhCs, and (f) current trends and limitations of such sensors.
- 408Yetisen, A. K.; Naydenova, I.; Da Cruz Vasconcellos, F.; Blyth, J.; Lowe, C. R. Holographic Sensors: Three-Dimensional Analyte-Sensitive Nanostructures and Their Applications Chem. Rev. 2014, 114, 10654– 10696 DOI: 10.1021/cr500116aGoogle Scholar408https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2cXhsFamsLbK&md5=9dcf0c029370183587a191c35d9e9910Holographic Sensors: Three-Dimensional Analyte-Sensitive Nanostructures and Their ApplicationsYetisen, Ali K.; Naydenova, Izabela; Vasconcellos, Fernando da Cruz; Blyth, Jeffrey; Lowe, Christopher R.Chemical Reviews (Washington, DC, United States) (2014), 114 (20), 10654-10696CODEN: CHREAY; ISSN:0009-2665. (American Chemical Society)A review. The purpose of this review is to (1) establish a theor. framework for holog. sensing, (2) define terminol. in holog. sensing, (3) demonstrate how holog. sensing fits into the existing body of sensing mechanisms, and (4) highlight gaps in the previous research. The goals of this review include integrating and summarizing what is known in holog. sensing, identifying where the major questions remain, and enabling others in the field to be able to replicate the existing exptl. setups for fabricating and interrogating holog. sensors. The scope of this review consists of the state-of-the-art techniques for producing holog. sensors, and their potential applications in research, industrial settings, and among the public. This review mainly covers holog. sensor research from 1990 to 2014, but also refers to earlier literature for historical developments and fundamentals. It also discusses the need for optical sensing, the fundamentals of holog., the origins of holog. sensors, holog. media and materials, fabrication techniques, sensing capabilities, readouts, and relevant theor. studies. This review concludes with a discussion of gaps within the field and how to overcome the perceived limitations of holog. sensors.
- 409Baker, J. E.; Sriram, R.; Miller, B. L. Two-Dimensional Photonic Crystals for Sensitive Microscale Chemical and Biochemical Sensing Lab Chip 2015, 15, 971– 990 DOI: 10.1039/C4LC01208AGoogle Scholar409https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2cXitFegtrbO&md5=8afbd3bb1555bb88db9d51eb3eecce86Two-dimensional photonic crystals for sensitive microscale chemical and biochemical sensingBaker, James E.; Sriram, Rashmi; Miller, Benjamin L.Lab on a Chip (2015), 15 (4), 971-990CODEN: LCAHAM; ISSN:1473-0189. (Royal Society of Chemistry)A review. Photonic crystals - optical devices able to respond to changes in the refractive index of a small vol. of space - are an emerging class of label-free chem.- and bio-sensors. This review focuses on one class of photonic crystal, in which light is confined to a patterned planar material layer of sub-wavelength thickness. These devices are small (on the order of tens to hundreds of microns square), suitable for incorporation into lab-on-a-chip systems, and in theory can provide exceptional sensitivity. We introduce the defining characteristics and basic operation of two-dimensional photonic crystal sensors, describe variations of their basic design geometry, and summarize reported detection results from chem. and biol. sensing expts.
- 410Advanced Photonic Structures for Biological and Chemical Detection; Fan, X., Ed.; Springer: New York, 2009.Google ScholarThere is no corresponding record for this reference.
- 411Luchansky, M. S.; Bailey, R. C. High-Q Optical Sensors for Chemical and Biological Analysis Anal. Chem. 2012, 84, 793– 821 DOI: 10.1021/ac2029024Google Scholar411https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC3MXhsFSjsbfP&md5=e30e8d65a356d70e5472ea3613c319d1High-Q Optical Sensors for Chemical and Biological AnalysisLuchansky, Matthew S.; Bailey, Ryan C.Analytical Chemistry (Washington, DC, United States) (2012), 84 (2), 793-821CODEN: ANCHAM; ISSN:0003-2700. (American Chemical Society)A review on high-quality factor (high-Q) optical sensors including major subsections on Whispering Gallery Mode Sensing; High-Q Optical Sensors: Geometries, Fabrication; Surface Chem., Device Functionalization, and Capture Agents; Recent Developments in Assay Design; Recent Applications of High-Q Optical Sensors; and Perspectives.
- 412Raymond, K. P.; Burgess, I. B.; Kinney, M. H.; Lončar, M.; Aizenberg, J. Combinatorial Wetting in Colour: An Optofluidic Nose Lab Chip 2012, 12, 3666– 3669 DOI: 10.1039/c2lc40489cGoogle Scholar412https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC38Xht1GgsrvK&md5=d8bd733221d37946acbcc13d98aabd02Combinatorial wetting in colour: an optofluidic noseRaymond, Kevin P.; Burgess, Ian B.; Kinney, Mackenzie H.; Loncar, Marko; Aizenberg, JoannaLab on a Chip (2012), 12 (19), 3666-3669CODEN: LCAHAM; ISSN:1473-0189. (Royal Society of Chemistry)The authors present a colorimetric litmus test for simple differentiation of org. liqs. based on wetting, which achieves chem. specificity without a significant sacrifice in portability or ease-of-use. Chem. specificity is derived from the combination of colorimetric wetting patterns produced by liqs. in an array of inverse opal films, each having a graded wettability, but using different surface groups to define that gradient.
- 413Biró, L. P.; Vigneron, J. P. Photonic Nanoarchitectures in Butterflies and Beetles: Valuable Sources for Bioinspiration Laser Photon. Rev. 2011, 5, 27– 51 DOI: 10.1002/lpor.200900018Google ScholarThere is no corresponding record for this reference.
- 414Niu, S.; Li, B.; Mu, Z.; Yang, M.; Zhang, J.; Han, Z.; Ren, L. Excellent Structure-Based Multifunction of Morpho Butterfly Wings: A Review J. Bionic Eng. 2015, 12, 170– 189 DOI: 10.1016/S1672-6529(14)60111-6Google ScholarThere is no corresponding record for this reference.
- 415Zhang, D.; Zhang, W.; Gu, J.; Fan, T.; Liu, Q.; Su, H.; Zhu, S. Inspiration from Butterfly and Moth Wing Scales: Characterization, Modeling, and Fabrication Prog. Mater. Sci. 2015, 68, 67– 96 DOI: 10.1016/j.pmatsci.2014.10.003Google ScholarThere is no corresponding record for this reference.
- 416Kinoshita, S.; Yoshioka, S.; Miyazaki, J. Physics of Structural Colors Rep. Prog. Phys. 2008, 71, 076401 DOI: 10.1088/0034-4885/71/7/076401Google ScholarThere is no corresponding record for this reference.
- 417Biró, L. P.; Kertész, K.; Vértesy, Z.; Bálint, Z. Photonic Nanoarchitectures Occurring in Butterfly Scales as Selective Gas/Vapor Sensors Proc. SPIE 2008, 7057, 705706 DOI: 10.1117/12.794910Google ScholarThere is no corresponding record for this reference.
- 418Eliason, C. M.; Shawkey, M. D. Rapid, Reversible Response of Iridescent Feather Color to Ambient Humidity Opt. Express 2010, 18, 21284– 21292 DOI: 10.1364/OE.18.021284Google ScholarThere is no corresponding record for this reference.
- 419Gao, Y.; Xia, Q.; Liao, G.; Shi, T. Sensitivity Analysis of a Bioinspired Refractive Index Based Gas Sensor J. Bionic Eng. 2011, 8, 323– 334 DOI: 10.1016/S1672-6529(11)60026-7Google ScholarThere is no corresponding record for this reference.
- 420Shawkey, M. D.; D’Alba, L.; Wozny, J.; Eliason, C.; Koop, J. A. H.; Jia, L. Structural Color Change Following Hydration and Dehydration of Iridescent Mourning Dove (Zenaida Macroura) Feathers Zoology 2011, 114, 59– 68 DOI: 10.1016/j.zool.2010.11.001Google Scholar420https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A280%3ADC%252BC3MvgsVWitQ%253D%253D&md5=e8cfff87ef264a80aee0f3a7f6c505a3Structural color change following hydration and dehydration of iridescent mourning dove (Zenaida macroura) feathersShawkey Matthew D; D'Alba Liliana; Wozny Joel; Eliason Chad; Koop Jennifer A H; Jia LiZoology (Jena, Germany) (2011), 114 (2), 59-68 ISSN:.Dynamic changes in integumentary color occur in cases as diverse as the neurologically controlled iridiphores of cephalopod skin and the humidity-responsive cuticles of longhorn beetles. By contrast, feather colors are generally assumed to be relatively static, changing by small amounts only over periods of months. However, this assumption has rarely been tested even though structural colors of feathers are produced by ordered nanostructures that are analogous to those in the aforementioned dynamic systems. Feathers are neither innervated nor vascularized and therefore any color change must be caused by external stimuli. Thus, we here explore how feathers of iridescent mourning doves Zenaida macroura respond to a simple stimulus: addition and evaporation of water. After three rounds of experimental wetting and subsequent evaporation, iridescent feather color changed hue, became more chromatic and increased in overall reflectance by almost 50%. To understand the mechanistic basis of this change, we used electron microscopy to examine macro- and nanostructures before and after treatment. Transmission electron microscopy and transfer matrix thin-film models revealed that color is produced by thin-film interference from a single (∼ 35 nm layer of keratin around the edge of feather barbules, beneath which lies a layer of air and melanosomes. After treatment, the most striking morphological difference was a twisting of colored barbules that exposed more of their surface area for reflection, explaining the observed increase in brightness. These results suggest that some plumage colors may be more malleable than previously thought, leading to new avenues for research on dynamic plumage color.
- 421Yang, X.; Peng, Z.; Zuo, H.; Shi, T.; Liao, G. Using Hierarchy Architecture of Morpho Butterfly Scales for Chemical Sensing: Experiment and Modeling Sens. Actuators, A 2011, 167, 367– 373 DOI: 10.1016/j.sna.2011.03.035Google Scholar421https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC3MXmtVCrsLk%253D&md5=6fd3b480028d89862a2a1d10ba66f5c9Using hierarchy architecture of Morpho butterfly scales for chemical sensing: Experiment and modelingYang, Xuefeng; Peng, Zhengchun; Zuo, Haibo; Shi, Tielin; Liao, GuanglanSensors and Actuators, A: Physical (2011), 167 (2), 367-373CODEN: SAAPEB; ISSN:0924-4247. (Elsevier B.V.)In this work, the hierarchical micro/nanostructures of Morpho butterfly scales were employed for chem. sensing purposes. We obsd. that the color and the brightness of the butterfly wings change obviously when the surrounding medium was altered. With an optical system setup, we quantified the shift of the major reflection peak and the change in peak intensity, which corresponds to the obsd. change of color and brightness. In order to guiding the engineering design of artificial butterfly scales as a new platform for chem. sensors, we further constructed two-dimensional optical models with three different geometrical designs. Rigorous coupled wave anal. technique was employed to analyze the models. By comparing the modeling results with expts., we identified the key characteristics of the butterfly scales that were relevant to chem. sensing applications. These characteristics should be implemented and optimized in designing and fabricating the bio-inspired sensors for sensitive and selective detection of closely related chems.
- 422Mouchet, S.; Deparis, O.; Vigneron, J. P. Unexplained High Sensitivity of the Reflectance of Porous Natural Photonic Structures to the Presence of Gases and Vapours in the Atmosphere Proc. SPIE 2012, 8424, 842425 DOI: 10.1117/12.921784Google ScholarThere is no corresponding record for this reference.
- 423Kertész, K.; Piszter, G.; Jakab, E.; Bálint, Z.; Vértesy, Z.; Biró, L. P. Color Change of Blue Butterfly Wing Scales in an Air - Vapor Ambient Appl. Surf. Sci. 2013, 281, 49– 53 DOI: 10.1016/j.apsusc.2013.01.037Google ScholarThere is no corresponding record for this reference.
- 424Han, Z.; Niu, S.; Yang, M.; Mu, Z.; Li, B.; Zhang, J.; Ye, J.; Ren, L. Unparalleled Sensitivity of Photonic Structures in Butterfly Wings RSC Adv. 2014, 4, 45214– 45219 DOI: 10.1039/C4RA06117AGoogle Scholar424https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2cXhsVCjtLrO&md5=c271dfbff2efe36755243852ce63448cUnparalleled sensitivity of photonic structures in butterfly wingsHan, Zhiwu; Niu, Shichao; Yang, Meng; Mu, Zhengzhi; Li, Bo; Zhang, Junqiu; Ye, Junfeng; Ren, LuquanRSC Advances (2014), 4 (85), 45214-45219CODEN: RSCACL; ISSN:2046-2069. (Royal Society of Chemistry)Butterflies are famous for their brilliant iridescent colors, which arise from the unparalleled photonic nanostructures of the scales on their wings. In this paper, the sensitivity characteristics of the photonic structures in butterfly wings to surrounding media were found. First, it was shown that the iridescent scales of Morpho menelaus butterfly give a different optical response to surrounding vapors of water, ether and ethanol. Then, the ultra-depth three-dimensional microscope and FESEM were used to observe the morphol. and nanostructures of butterfly wing scales. The high spectral response characteristics were identified by using an Ocean Optics spectrometer USB4000. It was found that the reflectance spectra of the Morpho menelaus butterfly scales could provide information about the nature of the surrounding vapors. Afterwards, the theory of multilayer-thin-film interference was used to analyze the mechanism of this sensitivity. It was detd. that the multilayer-thin-film interference structure constituted by alternating films with high and low refractive indexes, leading to the sensitivity of butterfly wings. The refractive indexes of surrounding media play an important role in gas sensitivity. These characteristics dramatically outperform those of existing nano-engineered photonic sensors and may have potential in the design of efficient and high sensitivity optical gas sensors.
- 425Piszter, G.; Kertész, K.; Vértesy, Z.; Bálint, Z.; Biró, L. P. Vapor Sensing of Pristine and ALD Modified Butterfly Wings Mater. Today Proc. 2014, 1, 216– 220 DOI: 10.1016/j.matpr.2014.09.025Google ScholarThere is no corresponding record for this reference.
- 426Wang, W.; Zhang, W.; Fang, X.; Huang, Y.; Liu, Q.; Gu, J.; Zhang, D. Demonstration of Higher Colour Response with Ambient Refractive Index in Papilio Blumei as Compared to Morpho Rhetenor Sci. Rep. 2014, 4, 5591 DOI: 10.1038/srep05591Google Scholar426https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2MXksVygtLc%253D&md5=e61b172421f8ecf6d32fd91b679673c1Demonstration of higher colour response with ambient refractive index in Papilio blumei as compared to MorphorhetenorWang, Wanlin; Zhang, Wang; Fang, Xiaotian; Huang, Yiqiao; Liu, Qinglei; Gu, Jiajun; Zhang, DiScientific Reports (2014), 4 (), 5591CODEN: SRCEC3; ISSN:2045-2322. (Nature Publishing Group)Multilayer structures are known to produce vivid iridescent coloration in many butterflies. Morpho butterflies are well known for their high reflectance, which appears to remain high over a wide range of viewing angles. Thus these butterflies have served as the inspiration for sensing materials. Using microscopic images and videos, we visually demonstrate that the color response with ambient refractive index of Papilio blumei is better than that of Morpho rhetenor. This result was also verified using measurements of the reflectance for different viewing angles. The finite-difference time-domain method was then used to simulate the microscopic pictures and reflections. Finally, the relationships between the structure, ambient refractive index, reflection and viewing angle are discussed in detail.
- 427Jiang, T.; Peng, Z.; Wu, W.; Shi, T.; Liao, G. Gas Sensing Using Hierarchical Micro/Nanostructures of Morpho Butterfly Scales Sens. Actuators, A 2014, 213, 63– 69 DOI: 10.1016/j.sna.2014.04.002Google Scholar427https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2cXotlWmsro%253D&md5=600e7eef226f5f4cfea5fb2ccdedaf00Gas sensing using hierarchical micro/nanostructures of Morpho butterfly scalesJiang, Ting; Peng, Zhengchun; Wu, Wenjun; Shi, Tielin; Liao, GuanglanSensors and Actuators, A: Physical (2014), 213 (), 63-69CODEN: SAAPEB; ISSN:0924-4247. (Elsevier B.V.)Demonstrated is the application of the hierarchical micro/nanostructures of Morpho didius butterfly scales for gas sensing. A reflective optical system was set up to detect the reflectance spectra of butterfly wing samples in a specific gas environment. Principle component anal. method was employed to discriminate and identify nitrogen, methanol and ethanol vapors according to the distribution of the projection points. Meanwhile, an appropriate 2D optical model of the butterfly scales was constructed with Rsoft software and theor. simulated the gas sensing performance by rigorous coupled wave anal. technique. In the theor. study, exposing the structures to vapors was modeled as vapor adsorption, resulting in the formation of nanometer-thick liq. films onto the structures, where the thickness of the film increased with the vapor concn. increasing. The exptl. and simulation results match well, confirming that the butterfly scales indeed have the sensitivity and selectivity for vapors sensing. As such, it is believed that an optimized artificial structure mimicking Morpho butterfly scales can be used as gas sensors for sensitive and selective detection of closely related vapors.
- 428Piszter, G.; Kertész, K.; Vértesy, Z.; Bálint, Z.; Biró, L. P. Substance Specific Chemical Sensing with Pristine and Modified Photonic Nanoarchitectures Occurring in Blue Butterfly Wing Scales Opt. Express 2014, 22, 22649– 22660 DOI: 10.1364/OE.22.022649Google ScholarThere is no corresponding record for this reference.
- 429Starkey, T. A.; Vukusic, P.; Potyrailo, R. A. Toward Bioinspired Nanostructures for Selective Vapor Sensing: Diverse Vapor-Induced Spectral Responses within Iridescent Scales of Morpho Butterflies MRS Online Proc. Libr. 2014, 1621, 197– 207 DOI: 10.1557/opl.2014.66Google ScholarThere is no corresponding record for this reference.
- 430Lysenko, S. I.; Kaganovich, E. B.; Kizyak, I. M.; Snopok, B. A. Multiparametric Chemical Sensor Based on Nanocrystalline Silicon Waveguide Sens. Lett. 2005, 3, 117– 125 DOI: 10.1166/sl.2005.025Google Scholar430https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD2MXhtFChtrjO&md5=0ee6e317d365b70e1f7105d842590418Multiparametric chemical sensor based on nanocrystalline silicon waveguideLysenko, S. I.; Kaganovich, E. B.; Kizyah, I. M.; Snopok, B. A.Sensor Letters (2005), 3 (2), 117-125CODEN: SLEEA3; ISSN:1546-198X. (American Scientific Publishers)New measurement protocol based on waveguide spectroscopy in the Kretschmann configuration combined with monitoring of light scattering from thin films was developed for gas sensor applications. The performance of the approach was successfully demonstrated for study the interaction of ethanol, acetone and water mols. with nanocomposite silicon nanocryst. film (nc-Si) as indicative examples. Simultaneous measurements of guided optical wave scattering and reflection coeffs. give comprehensive information for recognition of gas mols. adsorbed by nc-Si film. The sensing process is completely reversible and can be attribute to the adlayer formation (water), pore walls adsorption (acetone) and capillary condensation of the vapor into the pores (ethanol). Possible mechanisms of the processes are discussed.
- 431Oton, C. J.; Pancheri, L.; Gaburro, Z.; Pavesi, L.; Baratto, C.; Faglia, G.; Sberveglieri, G. Multiparametric Porous Silicon Gas Sensors with Improved Quality and Sensitivity Phys. Status Solidi A 2003, 197, 523– 527 DOI: 10.1002/pssa.200306557Google ScholarThere is no corresponding record for this reference.
- 432Wang, L.; Swensen, J. S. Dual-Transduction-Mode Sensing Approach for Chemical Detection Sens. Actuators, B 2012, 174, 366– 372 DOI: 10.1016/j.snb.2012.08.036Google Scholar432https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC38XhsFymt7vN&md5=122082f4780f578ca485bac26fa22278Dual-transduction-mode sensing approach for chemical detectionWang, Liang; Swensen, James S.Sensors and Actuators, B: Chemical (2012), 174 (), 366-372CODEN: SABCEB; ISSN:0925-4005. (Elsevier B.V.)Smart devices such as electronic nose have been developed for application in many fields like national security, defense, environmental regulation, health care, pipeline monitoring and food anal. Despite a large array of individual sensors, the resolving power of these devices can still be improved to identify a target at a very low concn. out of a mixt. of odors, if different types of transductions are employed in concert as a set of sensing responses to distinguish one odor from another. Here, a new sensor architecture is proposed enabling different types of transduction signals in parallel on the same individual sensor. This architecture is demonstrated using a light emitting org. field-effect transistor (LEOFET) operated at a dual-transduction mode, as a proof-of-concept. Sensing response was obsd. on both elec. and optical output signals from a green LEOFET upon exposure to an explosive taggant, with optical signal exhibiting much higher sensitivity. This new sensor architecture opens a field of devices of synergic capabilities to distinguish chem. and biol. targets.
- 433Loui, A.; Sirbuly, D. J.; Elhadj, S.; McCall, S. K.; Hart, B. R.; Ratto, T. V. Detection and Discrimination of Pure Gases and Binary Mixtures Using a Dual-Modality Microcantilever Sensor Sens. Actuators, A 2010, 159, 58– 63 DOI: 10.1016/j.sna.2010.03.004Google Scholar433https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC3cXksFSks7s%253D&md5=923a4826cac779b903689916ddf4251aDetection and discrimination of pure gases and binary mixtures using a dual-modality microcantilever sensorLoui, A.; Sirbuly, D. J.; Elhadj, S.; McCall, S. K.; Hart, B. R.; Ratto, T. V.Sensors and Actuators, A: Physical (2010), 159 (1), 58-63CODEN: SAAPEB; ISSN:0924-4247. (Elsevier B.V.)A new method for detecting and discriminating pure gases and binary mixts. was investigated. This approach is based on two distinct phys. mechanisms which can be simultaneously employed within a single microcantilever: heat dissipation and resonant damping in the viscous regime. An exptl. study of the heat dissipation mechanism indicates that the sensor response is directly correlated to the thermal cond. of the gaseous analyte. A theor. data set of resonant damping was generated corresponding to the gas mixts. examd. in the thermal response expts. The combination of the thermal and resonant response data yields more distinct analyte signatures that cannot otherwise be obtained from the detection modes individually.
- 434Chen, I. S.; Stawasz, M.; DiMascio, S. K.; Welch, J. J.; Neuner, J. W.; Chen, P. S. H.; DiMeo, F., Jr Micromachined Chemical Sensor with Dual-Transduction Mechanisms Appl. Phys. Lett. 2005, 86, 173510 DOI: 10.1063/1.1915541Google ScholarThere is no corresponding record for this reference.
- 435Qazi, M.; Vogt, T.; Koley, G. Two-Dimensional Signatures for Molecular Identification Appl. Phys. Lett. 2008, 92, 103120 DOI: 10.1063/1.2897295Google ScholarThere is no corresponding record for this reference.
- 436Ionescu, R. Combined Seebeck and Resistive SnO2 Gas Sensors, a New Selective Device Sens. Actuators, B 1998, 48, 392– 394 DOI: 10.1016/S0925-4005(98)00077-XGoogle Scholar436https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADyaK1cXkslamtrc%253D&md5=1b84da2212e16850639bf05833d62e6bCombined seebeck and resistive SnO2 gas sensors, a new selective deviceIonescu, RaduSensors and Actuators, B: Chemical (1998), 48 (1-3), 392-394CODEN: SABCEB; ISSN:0925-4005. (Elsevier Science S.A.)Simultaneous measurements of elec. resistance R and Seebeck emf. Vs of thick film SnO2 gas sensors were performed in air contg. different concns. pi of reducing gas (ethanol vapors, CO, CH4, C2H6 were successively used). The graphical representations of the Vs vs. ln h values both for the identification of the reducing gas (selectivity) and for the detn. of gas concn.
- 437Williams, A.; Williams, L. D. Contrivance for Automatically Detecting the Presence of Certain Gases and Vapors. U.S. Patent 1,143,473, 1915.Google ScholarThere is no corresponding record for this reference.
- 438Bielanski, A.; Deren, J.; Haber, J. Electric Conductivity and Catalytic Activity of Semiconducting Oxide Catalysts Nature 1957, 179, 668– 669 DOI: 10.1038/179668a0Google ScholarThere is no corresponding record for this reference.
- 439King, W. H., Jr. Piezoelectric Sorption Detector Anal. Chem. 1964, 36, 1735– 1739 DOI: 10.1021/ac60215a012Google Scholar439https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADyaF2cXkslans7c%253D&md5=c7504c9fe0139e353e3e7e9fd552f786Piezoelectric sorption detectorKing, William H., Jr.(1964), 36 (9), 1735-9CODEN: ANCHAM; ISSN:0003-2700.Piezoelec. quartz crystals coated with 5-50 γ of substrate were used as gas chromatography detectors. Both the amplitude and frequency of vibration of the crystals were changed by the absorption of gas. A 9-Mc. crystal showed a linear response ∼500 cycles/sec./γ of wt. increase, and the signal could be directly integrated and presented digitally on a frequency counter. Presentation of the amplitude signal was simpler but less precise than the frequency signal. A crystal coated with 20 γ of squalane in a detector vol. of 0.02 cc. had a response time of 0.05 sec. The response to 6 aliphatic and aromatic hydrocarbons was a linear function of the partition coeffs. and of the sp. retention vols. The sensitivity increased with the mol. wt. of the solute and was independent of the carrier gas. By choice of polar substrates the detectors can be made selective and the crystals can be used as integral detectors in the case of strongly adsorbed or reactive gases.
- 440Bergman, I. Rapid-Response Atmospheric Oxygen Monitor Based on Fluorescence Quenching Nature 1968, 218, 396 DOI: 10.1038/218396a0Google ScholarThere is no corresponding record for this reference.
- 441Holmberg, M.; Artursson, T. Drift Compensation, Standards, and Calibration Methods. In Handbook of Machine Olfaction: Electronic Nose Technology; Pearce, T. C.; Schiffman, S. S.; Nagle, H. T.; Gardner, J. W., Eds.; Wiley VCH: 2002; pp 325– 346.Google ScholarThere is no corresponding record for this reference.
- 442Lakkis, S.; Younes, R.; Alayli, Y.; Sawan, M. Review of Recent Trends in Gas Sensing Technologies and Their Miniaturization Potential Sens. Rev. 2014, 34, 24– 35 DOI: 10.1108/SR-11-2012-724Google ScholarThere is no corresponding record for this reference.
- 443Lonergan, M. C.; Severin, E. J.; Doleman, B. J.; Beaber, S. A.; Grubbs, R. H.; Lewis, N. S. Array-Based Vapor Sensing Using Chemically Sensitive, Carbon Black-Polymer Resistors Chem. Mater. 1996, 8, 2298– 2312 DOI: 10.1021/cm960036jGoogle Scholar443https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADyaK28XltV2htL4%253D&md5=6352b32f43e9f790ddafd79db9c41d06Array-based vapor sensing using chemically sensitive, carbon black-polymer resistorsLonergan, Mark C.; Severin, Erik J.; Doleman, Brett J.; Beaber, Sara A.; Grubbs, Robert H.; Lewis, Nathan S.Chemistry of Materials (1996), 8 (9), 2298-2312CODEN: CMATEX; ISSN:0897-4756. (American Chemical Society)The authors describe herein the construction of a simple, low-power, broadly responsive vapor sensor. C black-org. polymer composites swell reversibly upon exposure to vapors. Thin films of C black-org. polymer composites were deposited across two metallic leads, with swelling-induced resistance changes of the films signaling the presence of vapors. To identify and classify vapors, arrays of such vapor-sensing elements were constructed, with each element contg. the same C black conducting phase but a different org. polymer as the insulating phase. The differing gas-solid partition coeffs. for the various polymers of the sensor array produce a pattern of resistance changes that can be used to classify vapors and vapor mixts. This type of sensor array was shown to resolve common org. solvents, including mols. of different classes (such as aroms. from alcs.) as well as those within a particular class (such as benzene from toluene and MeOH from EtOH). The response of an individual composite to varying concns. of solvent is consistent with the predictions of percolation theory. Accordingly, significant increases in the signals of array elements were obsd. for C black-polymer composites that were operated near their percolation thresholds.
- 444Carey, J. R.; Suslick, K. S.; Hulkower, K. I.; Imlay, J. A.; Imlay, K. R. C.; Ingison, C. K.; Ponder, J. B.; Sen, A.; Wittrig, A. E. Rapid Identification of Bacteria with a Disposable Colorimetric Sensing Array J. Am. Chem. Soc. 2011, 133, 7571– 7576 DOI: 10.1021/ja201634dGoogle Scholar444https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC3MXltlejs7g%253D&md5=aa4697ba4f8d74488daf50be97360f2fRapid Identification of Bacteria with a Disposable Colorimetric Sensing ArrayCarey, James R.; Suslick, Kenneth S.; Hulkower, Keren I.; Imlay, James A.; Imlay, Karin R. C.; Ingison, Crystal K.; Ponder, Jennifer B.; Sen, Avijit; Wittrig, Aaron E.Journal of the American Chemical Society (2011), 133 (19), 7571-7576CODEN: JACSAT; ISSN:0002-7863. (American Chemical Society)Rapid identification of both species and even specific strains of human pathogenic bacteria grown on std. agar has been achieved from the volatiles they produce using a disposable colorimetric sensor array in a Petri dish imaged with an inexpensive scanner. All 10 strains of bacteria tested, including Enterococcus faecalis and Staphylococcus aureus and their antibiotic-resistant forms, were identified with 98.8% accuracy within 10 h, a clin. important time frame. Furthermore, the colorimetric sensor arrays also proved useful as a simple research tool for the study of bacterial metab. and as an easy method for the optimization of bacterial prodn. of fine chems. or other fermn. processes.
- 445LaGasse, M. K.; Rankin, J. M.; Askim, J. R.; Suslick, K. S. Colorimetric Sensor Arrays: Interplay of Geometry, Substrate and Immobilization Sens. Actuators, B 2014, 197, 116– 122 DOI: 10.1016/j.snb.2014.01.102Google Scholar445https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2cXms1Cmsbw%253D&md5=d75e30a87bca4230cf6e24dd0972cb65Colorimetric sensor arrays: Interplay of geometry, substrate and immobilizationLaGasse, Maria K.; Rankin, Jacqueline M.; Askim, Jon R.; Suslick, Kenneth S.Sensors and Actuators, B: Chemical (2014), 197 (), 116-122CODEN: SABCEB; ISSN:0925-4005. (Elsevier B.V.)This study addresses the interplay of geometry, substrate, and dye immobilization method on colorimetric sensor array performance. Arrays of cross-responsive dyes were exposed to either ammonia or sulfur dioxide gas at their permissible exposure levels (PEL) or their immediately dangerous to life or health (IDLH) concns. and their colorimetric responses analyzed. Two-dimensional and linear arrays in flow cells were compared for flow path uniformity. Substrate effects were explored using arrays of 36 dyes immobilized in organically modified silica sol-gel (ormosil) formulations printed on six common substrates in three classes: impermeable (glass slides and polyethylene terephthalate), cellulose based (printer paper and chromatog. paper with silica gel), and porous polymer membranes (polypropylene and polyvinylidene difluoride). The effect of immobilization of dyes in an ormosil vs. in a plasticizer (i.e., a viscous semi-liq.) was also compared. The linear geometry showed a more homogeneous flow path than obtained with the two-dimensional array, which contributes to higher overall response, faster response, and better reproducibility. Arrays printed on impermeable substrates showed long response times attributed to slow diffusion of the analyte through the spot, and those printed on cellulose based substrates showed high noise caused by macroscale surface texturing. Arrays printed on porous polymer substrates showed the best spot quality and reproducibility, fastest response, and lowest noise. Finally, plasticizer and ormosils proved to be comparable immobilization matrixes for colorants, and the preferred choice depends on the combination of dye, immobilization method, and substrate.
- 446Starkey, T.Towards Bio-Inspired Photonic Vapour Sensors. Doctoral Thesis, School of Physics, University of Exeter, 2014.Google ScholarThere is no corresponding record for this reference.
- 447Hartley, J. G.; Bonam, R. K. Methods for Fabricating Three-Dimensional Nano-Scale Structures and Devices. U.S. Patent 9,177,817, 2015.Google ScholarThere is no corresponding record for this reference.
- 448Watanabe, K.; Hoshino, T.; Kanda, K.; Haruyama, Y.; Matsui, S. Brilliant Blue Observation from a Morpho-Butterfly-Scale Quasi-Structure Jpn. J. Appl. Phys. 2005, 44, L48– L50 DOI: 10.1143/JJAP.44.L48Google Scholar448https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD2MXjtFWksL4%253D&md5=632fd9cd19d6d7c26db59ffd229031fdBrilliant blue observation from a Morpho-butterfly-scale quasi-structureWatanabe, Keiichiro; Hoshino, Takayuki; Kanda, Kazuhiro; Haruyama, Yuichi; Matsui, ShinjiJapanese Journal of Applied Physics, Part 2: Letters & Express Letters (2005), 44 (1-7), L48-L50CODEN: JAPLD8 ISSN:. (Japan Society of Applied Physics)The Morpho-butterfly wing reflects interfered brilliant blue, which originates from nanostructures on its scales, for any incidence angle of white light. The authors have, for the 1st time, fabricated a Morpho-butterfly-scale quasi-structure using focused-ion-beam CVD (FIB-CVD) and obsd. brilliant blue reflection from this quasi-structure with an optical microscope. The authors measured the reflection from real Morpho-butterfly scales and from the quasi-structure with a photonic multi-channel spectral analyzer system. The reflection spectra of the quasi-structure were very similar to those of Morpho-butterfly scales.
- 449Wu, C.-S.; Lin, C.-F.; Lin, H.-Y.; Lee, C.-L.; Chen, C.-D. Polymer-Based Photonic Crystals Fabricated with Single-Step Electron-Beam Lithography Adv. Mater. 2007, 19, 3052– 3056 DOI: 10.1002/adma.200602471Google ScholarThere is no corresponding record for this reference.
- 450Zhang, S.; Chen, Y. Nanofabrication and Coloration Study of Artificial Morpho Butterfly Wings with Aligned Lamellae Layers Sci. Rep. 2015, 5, 16637 DOI: 10.1038/srep16637Google Scholar450https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2MXhvVOru7%252FO&md5=e85925d0134ea63112353baddfeef484Nanofabrication and coloration study of artificial Morpho butterfly wings with aligned lamellae layersZhang, Sichao; Chen, YifangScientific Reports (2015), 5 (), 16637CODEN: SRCEC3; ISSN:2045-2322. (Nature Publishing Group)The bright and iridescent blue color from Morpho butterfly wings has attracted worldwide attentions to explore its mysterious nature for long time. Although the physics of structural color by the nanophotonic structures built on the wing scales has been well established, replications of the wing structure by std. top-down lithog. still remains a challenge. This paper reports a tech. breakthrough to mimic the blue color of Morpho butterfly wings, by developing a novel nanofabrication process, based on electron beam lithog. combined with alternate PMMA/LOR development/dissoln., for photonic structures with aligned lamellae multilayers in colorless polymers. The relationship between the coloration and geometric dimensions as well as shapes is systematically analyzed by solving Maxwell's Equations with a finite domain time difference simulator. Careful characterization of the mimicked blue by spectral measurements under both normal and oblique angles are carried out. Structural color in blue reflected by the fabricated wing scales, is demonstrated and further extended to green as an application exercise of the new technique. The effects of the regularity in the replicas on coloration are analyzed. In principle, this approach establishes a starting point for mimicking structural colors beyond the blue in Morpho butterfly wings.
- 451Siddique, R. H.; Diewald, S.; Leuthold, J.; Hölscher, H. Theoretical and Experimental Analysis of the Structural Pattern Responsible for the Iridescence of Morpho Butterflies Opt. Express 2013, 21, 14351– 14361 DOI: 10.1364/OE.21.014351Google Scholar451https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A280%3ADC%252BC3sjkt1yjug%253D%253D&md5=ffb9c229f0b574a546e14d98af88d970Theoretical and experimental analysis of the structural pattern responsible for the iridescence of Morpho butterfliesSiddique Radwanul Hasan; Diewald Silvia; Leuthold Juerg; Holscher HendrikOptics express (2013), 21 (12), 14351-61 ISSN:.Morpho butterflies are well-known for their iridescence originating from nanostructures in the scales of their wings. These optical active structures integrate three design principles leading to the wide angle reflection: alternating lamellae layers, "Christmas tree" like shape, and offsets between neighboring ridges. We study their individual effects rigorously by 2D FEM simulations of the nanostructures of the Morpho sulkowskyi butterfly and show how the reflection spectrum can be controlled by the design of the nanostructures. The width of the spectrum is broad (≈ 90 nm) for alternating lamellae layers (or "brunches") of the structure while the "Christmas tree" pattern together with a height offset between neighboring ridges reduces the directionality of the reflectance. Furthermore, we fabricated the simulated structures by e-beam lithography. The resulting samples mimicked all important optical features of the original Morpho butterfly scales and feature the intense blue iridescence with a wide angular range of reflection.
- 452Aryal, M.; Ko, D.-H.; Tumbleston, J. R.; Gadisa, A.; Samulski, E. T.; Lopez, R. Large Area Nanofabrication of Butterfly Wings Three Dimensional Ultrastructures J. Vac. Sci. Technol. B 2012, 30, 061802 DOI: 10.1116/1.4759461Google ScholarThere is no corresponding record for this reference.
- 453Poncelet, O.; Tallier, G.; Mouchet, S. R.; Crahay, A.; Rasson, J.; Kotipalli, R.; Deparis, O.; Francis, L. A. Vapour Sensitivity of an ALD Hierarchical Photonic Structure Inspired by Morpho Bioinspir. Biomim. 2016, 11, 036011 DOI: 10.1088/1748-3190/11/3/036011Google ScholarThere is no corresponding record for this reference.
- 454Siddique, R. H.; Hünig, R.; Faisal, A.; Lemmer, U.; Hölscher, H. Fabrication of Hierarchical Photonic Nanostructures Inspired by Morpho Butterflies Utilizing Laser Interference Lithography Opt. Mater. Express 2015, 5, 996– 1005 DOI: 10.1364/OME.5.000996Google ScholarThere is no corresponding record for this reference.
- 455England, G.; Kolle, M.; Kim, P.; Khan, M.; Muñoz, P.; Mazur, E.; Aizenberg, J. Bioinspired Micrograting Arrays Mimicking the Reverse Color Diffraction Elements Evolved by the Butterfly Pierella Luna Proc. Natl. Acad. Sci. U. S. A. 2014, 111, 15630– 15634 DOI: 10.1073/pnas.1412240111Google Scholar455https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2cXhs1yhtb7M&md5=eb3d783489a63cd8157a95b5ff9381feBioinspired micrograting arrays mimicking the reverse color diffraction elements evolved by the butterfly Pierella lunaEngland, Grant; Kolle, Mathias; Kim, Philseok; Khan, Mughees; Munoz, Philip; Mazur, Eric; Aizenberg, JoannaProceedings of the National Academy of Sciences of the United States of America (2014), 111 (44), 15630-15634CODEN: PNASA6; ISSN:0027-8424. (National Academy of Sciences)Recently, diffraction elements that reverse the color sequence normally obsd. in planar diffraction gratings were found in the wing scales of the butterfly Pierella luna. The authors describe the creation of an artificial photonic material mimicking this reverse color-order diffraction effect. The bioinspired system consists of ordered arrays of vertically oriented microdiffraction gratings. They present a detailed anal. and modeling of the coupling of diffraction resulting from individual structural components and demonstrate its strong dependence on the orientation of the individual miniature gratings. This photonic material could provide a basis for novel developments in biosensing, anticounterfeiting, and efficient light management in photovoltaic systems and light-emitting diodes.
- 456Moos, R.; Sahner, K.; Fleischer, M.; Guth, U.; Barsan, N.; Weimar, U. Solid State Gas Sensor Research in Germany - A Status Report Sensors 2009, 9, 4323– 4365 DOI: 10.3390/s90604323Google ScholarThere is no corresponding record for this reference.
- 457Harper, W. J. The Strengths and Weaknesses of the Electronic Nose. In Headspace Analysis of Foods and Flavors; Rouseff, R.; Cadwallader, K., Eds.; Springer US: 2001; Vol. 488, pp 59– 71.Google ScholarThere is no corresponding record for this reference.
- 458Stetter, J. R.; Papageorge, M.High Volume Chemical Gas Sensors: Collision of Two Worlds Semi-Fab&Chemi-Product; MEMS Technol. Symp. MEPTEC: San Jose, CA, May 20, 2015; http://meptec.org/Resources/11%20-%20Stetter.pdf (accessed July 27, 2016).Google ScholarThere is no corresponding record for this reference.
- 459Schweizer-Berberich, M.; Strathmann, S.; Göpel, W.; Sharma, R.; Peyre-Lavigne, A. Filters for Tin Dioxide CO Gas Sensors to Pass the UL2034 Standard Sens. Actuators, B 2000, 66, 34– 36 DOI: 10.1016/S0925-4005(99)00334-2Google Scholar459https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD3cXlslejurs%253D&md5=38a7bc9283f8b42640147f899ccb9b97Filters for tin dioxide CO gas sensors to pass the UL2034 standardSchweizer-Berberich, M.; Strathmann, S.; Gopel, W.; Sharma, R.; Peyre-Lavigne, A.Sensors and Actuators, B: Chemical (2000), 66 (1-3), 34-36CODEN: SABCEB; ISSN:0925-4005. (Elsevier Science S.A.)CO gas sensors have to fulfil the requirements of stds. like the UL2034 or BS7860. Unfortunately, tin oxide gas sensors are also highly sensitive to volatile org. compds. (VOCs) like long chain hydrocarbons, alcs. or Et acetate. These stds. require negligible interference in cross-sensitivity tests of CO sensors. To fulfil the stds., charcoal filters were used combined with a micromachined SnO2 sensor. The latter was operated in a pulsed mode. Sensors with optimized size and material parameters of the charcoal filters fulfil the UL2034. The sensors are characterized by elec. measurements as required by these stds. The filters are characterized by SEM, EDX, BET and TG/DSC.
- 460Kitsukawa, S.; Nakagawa, H.; Fukuda, K.; Asakura, S.; Takahashi, S.; Shigemori, T. Interference Elimination for Gas Sensor by Catalyst Filters Sens. Actuators, B 2000, 65, 120– 121 DOI: 10.1016/S0925-4005(99)00463-3Google Scholar460https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD3cXksFKhsLg%253D&md5=d40a8b91fff9e3818eede55117dbc0b5The interference elimination for gas sensor by catalyst filtersKitsukawa, S.; Nakagawa, H.; Fukuda, K.; Asakura, S.; Takahashi, S.; Shigemori, T.Sensors and Actuators, B: Chemical (2000), 65 (1-3), 120-121CODEN: SABCEB; ISSN:0925-4005. (Elsevier Science S.A.)A method to eliminate alc. interference for a CO gas sensor using oxide semiconductor was studied. Some oxidizing and reducing agents were tested as filtering materials; Nafion was the most effective. This property was improved by treatment to form the Nafion into complete H-type before measurement. Elimination capability was correlated with the acidity of filtering materials.
- 461MicroDock II Automated Instrument Docking Station; 2010; http://www.honeywellanalytics.com/~/media/honeywell-analytics/products/microdock-ii/documents/english/microdockiidatasheet539614en.pdf?la=en (accessed July 27, 2016).Google ScholarThere is no corresponding record for this reference.
- 462Fido X3 Explosives Trace Detector; 2015; http://www.flir.com (accessed July 27, 2016).Google ScholarThere is no corresponding record for this reference.
- 463López-Ruiz, N.; Martínez-Olmos, A.; Pérez De Vargas-Sansalvador, I. M.; Fernández-Ramos, M. D.; Carvajal, M. A.; Capitan-Vallvey, L. F.; Palma, A. J. Determination of O2 Using Colour Sensing from Image Processing with Mobile Devices Sens. Actuators, B 2012, 171–172, 938– 945 DOI: 10.1016/j.snb.2012.06.007Google Scholar463https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC38XpvVOru7o%253D&md5=71fc329241e4929ad4234033132dc068Determination of O2 using color sensing from image processing with mobile devicesLopez-Ruiz, N.; Martinez-Olmos, A.; Perez de Vargas-Sansalvador, I. M.; Fernandez-Ramos, M. D.; Carvajal, M. A.; Capitan-Vallvey, L. F.; Palma, A. J.Sensors and Actuators, B: Chemical (2012), 171-172 (), 938-945CODEN: SABCEB; ISSN:0925-4005. (Elsevier B.V.)This paper presents a portable instrument designed and characterized for the detn. of gaseous oxygen. It is based on quenching the luminescence intensity of the platinum octaethylporphyrin complex when it is excited, using a light-emitting diode (LED) with an emission peak at 380 nm. The luminescence emitted by the platinum complex is detected by taking an image with a color CCD micro-camera integrated in the prototype which makes it possible to do a two-dimensional anal. of the luminescence. This image is processed by a microcontroller to obtain the red color component of the RGB color space, thus discarding any unnecessary color information. The processing is carried out for the pixels over a large area of the sensing membrane, which allows for a statistical treatment of the obtained data. The measured R-value for the membrane can be directly related to the concn. of the surrounding oxygen. The resulting instrument was fully characterized and calibrated, including drifts due to temp. and time. An application for Android camera devices such as smart phones was developed to use them as detectors and image processors to provide a prediction of the gaseous oxygen concn.
- 464Askim, J. R.; Suslick, K. S. Hand-Held Reader for Colorimetric Sensor Arrays Anal. Chem. 2015, 87, 7810– 7816 DOI: 10.1021/acs.analchem.5b01499Google Scholar464https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2MXhtFyrurrN&md5=54e530165e50dc8d84aec0f92d70d3f0Hand-Held Reader for Colorimetric Sensor ArraysAskim, Jon R.; Suslick, Kenneth S.Analytical Chemistry (Washington, DC, United States) (2015), 87 (15), 7810-7816CODEN: ANCHAM; ISSN:0003-2700. (American Chemical Society)An inexpensive hand-held device for anal. of colorimetric sensor arrays (CSAs) was developed. The device makes use of a contact image sensor (CIS), technol. commonly used in business card scanners, to rapidly collect low-noise colorimetric data for chem. sensing. The lack of moving parts and insensitivity to vibration allow for lower noise and improved scan rates compared to other digital imaging techniques (e.g., digital cameras, flatbed scanners); signal-to-noise ratios are a factor of 3-10 higher than currently used methods, and scan rates are up to 250 times faster without compromising sensitivity. The device is capable of real-time chem. anal. at scan rates up to 48 Hz.
- 465Dini, F.; Filippini, D.; Paolesse, R.; Lundström, I.; Di Natale, C. Computer Screen Assisted Digital Photography Sens. Actuators, B 2013, 179, 46– 53 DOI: 10.1016/j.snb.2012.10.092Google Scholar465https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC38Xhs12iu7jM&md5=ea902903f8ad5868ec33ed7e88a7c1ffComputer screen assisted digital photographyDini, Francesca; Filippini, Daniel; Paolesse, Roberto; Lundstrom, Ingemar; Di Natale, CorradoSensors and Actuators, B: Chemical (2013), 179 (), 46-53CODEN: SABCEB; ISSN:0925-4005. (Elsevier B.V.)The computer screen photo-assisted techniques (CSPT) were developed during the last 10 years through an extensive collaboration between University of Rome Tor Vergata and Linkoeping University in Sweden. CSPT has thus evolved into a concept the authors now call computer screen assisted digital photog., yielding detailed information about the interaction between color indicators and (volatile) analytes. The authors give a brief summary of the CSPT concept and its connection to digital photog. The authors conc., however, on the most recent results, which were obtained by using most of the degrees of freedom offered by a computer screen as a light source and a digital (web) camera as a detector. Thus, the authors describe in detail recent expts. on cotton yarns impregnated with color indicators for volatile org. mols. The interaction between the color indicators and mols., like trimethylamine, was studied by CSPT in high dynamic imaging together with a background noise limiting algorithm. The simultaneous use of the last two addns. to the CSPT concept considerably enhances the chem. sensing ability of CSPT. The collaboration between Rome and Linkoeping has generated a useful platform for further developments of chem. anal. with a ubiquitous instrumentation, a (computer) screen and a web camera. This technique is aimed at facilitating the assembly of opto-chem. sensors with evident benefits in the redn. of cost of sensor systems and in an increased integrability with the existent telecommunication infrastructures.
- 466Jing, L.; Ami, H.; Yijiang, L.; Beomseok, K.; Enid Contes-de, J. A Phone-Sensor for Trace Chemical Detection. In 43rd Intl. Conf. Environm. Syst.; American Institute of Aeronautics and Astronautics: 2013.Google ScholarThere is no corresponding record for this reference.
- 467Fiddes, L. K.; Yan, N. RFID Tags for Wireless Electrochemical Detection of Volatile Chemicals Sens. Actuators, B 2013, 186, 817– 823 DOI: 10.1016/j.snb.2013.05.008Google Scholar467https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC3sXhtVensLrI&md5=b992e1b942a4d108e64bfc6fc569d0c4RFID tags for wireless electrochemical detection of volatile chemicalsFiddes, Lindsey K.; Yan, NingSensors and Actuators, B: Chemical (2013), 186 (), 817-823CODEN: SABCEB; ISSN:0925-4005. (Elsevier B.V.)This work outlines a new approach for the construction of a wireless and battery-free broad response vapor sensor. Carbon black/org. polymer composites are known to swell reversibly upon exposure to volatile chems. The authors integrated these types of composites into the electronic elements of a conventional passive RFID tag circuitry to produce resistance changes that result in a change in the RFID tag's output signal frequency and amplitude. To identify vapors, arrays of RFID tags with such vapor-sensing elements were constructed, with each tag contg. carbon black as the conducting element and a polymer as the sensing element. The different gas-solid partition coeffs. for the polymers in the sensor array produce a unique pattern of signal changes that can be used to classify vapors. This sensor array was able to identify and quantify several vapors of interest (water, ammonia, ethanol and toluene).
- 468Rumens, C. V.; Ziai, M. A.; Belsey, K. E.; Batchelor, J. C.; Holder, S. J. Swelling of PDMS Networks in Solvent Vapours; Applications for Passive RFID Wireless Sensors J. Mater. Chem. C 2015, 3, 10091– 10098 DOI: 10.1039/C5TC01927CGoogle Scholar468https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2MXhtlCkt73N&md5=328621a472caab5ffd83b67c8317301eSwelling of PDMS networks in solvent vapours; applications for passive RFID wireless sensorsRumens, C. V.; Ziai, M. A.; Belsey, K. E.; Batchelor, J. C.; Holder, S. J.Journal of Materials Chemistry C: Materials for Optical and Electronic Devices (2015), 3 (39), 10091-10098CODEN: JMCCCX; ISSN:2050-7534. (Royal Society of Chemistry)The relative degree of swelling of a poly(dimethylsiloxane) (PDMS) network in org. vapors is demonstrated to be related to the chem. and phys. properties of the org. compds. The swelling ratio, based on vol. change, QV, is directly correlated with the Hansen soly. parameters, δd, δp and δh and the vapor pressures of the org. vapors employed. A practical use for such PDMS networks in combination with an understanding of the relationship is demonstrated by the use of PDMS as a mech. actuator in a prototype wireless RFID passive sensor. The swelling of the PDMS displaces a feed loop resulting in an increase in transmitted power, at a fixed distance.
- 469Lee, J. S.; Oh, J.; Jun, J.; Jang, J. Wireless Hydrogen Smart Sensor Based on Pt/Graphene-Immobilized Radio-Frequency Identification Tag ACS Nano 2015, 9, 7783– 7790 DOI: 10.1021/acsnano.5b02024Google Scholar469https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2MXhtVars7vO&md5=805b74d6ba8fc859396962a9aa6b5033Wireless Hydrogen Smart Sensor Based on Pt/Graphene-Immobilized Radio-Frequency Identification TagLee, Jun Seop; Oh, Jungkyun; Jun, Jaemoon; Jang, JyongsikACS Nano (2015), 9 (8), 7783-7790CODEN: ANCAC3; ISSN:1936-0851. (American Chemical Society)Hydrogen, a clean-burning fuel, is of key importance to various industrial applications, including fuel cells and the aerospace and automotive industries. However, hydrogen gas is odorless, colorless, and highly flammable; thus, appropriate safety protocol implementation and monitoring are essential. Highly sensitive hydrogen-gas leak detection and surveillance systems are needed; addnl., the ability to monitor large areas (e.g., cities) via wireless networks is becoming increasingly important. The authors introduce a radio frequency identification (RFID)-based wireless smart-sensor system, composed of a Pt-decorated reduced graphene oxide (Pt_rGO)-immobilized RFID sensor tag and an RFID-reader antenna-connected network analyzer to detect hydrogen gas. The Pt_rGOs, produced using a simple chem. redn. process, were immobilized on an antenna pattern in the sensor tag through spin coating. The resulting Pt_rGO-based RFID sensor tag exhibited a high sensitivity to hydrogen gas at unprecedentedly low concns. (1 ppm), with wireless communication between the sensor tag and RFID-reader antenna. The wireless sensor tag demonstrated flexibility and a long lifetime due to the strong immobilization of Pt_rGOs on the substrate and battery-independent operation during hydrogen sensing, resp.
- 470Weigel, C.; Schneider, M.; Schmitt, J.; Hoffmann, M.; Kahl, S.; Jurisch, R. Self-Sufficient Sensor for Oxygen Detection in Packaging Via Radio-Frequency Identification J. Sens. Sens. Syst. 2015, 4, 179– 186 DOI: 10.5194/jsss-4-179-2015Google ScholarThere is no corresponding record for this reference.
- 471Nguyen, D. S.; Le, N. N.; Lam, T. P.; Fribourg-Blanc, E.; Dang, M. C.; Tedjini, S. Development of Novel Wireless Sensor for Food Quality Detection Adv. Nat. Sci.: Nanosci. Nanotechnol. 2015, 6, 045004 DOI: 10.1088/2043-6262/6/4/045004Google ScholarThere is no corresponding record for this reference.
- 472Telid257 RFID Moisture Sensor Transponder; microsensys GmbH: Erfurt, Germany; http://www.microsensys.de/fileadmin/user_upload/datasheets/sensoren/TELID257-01.pdf (accessed July 27, 2016) .Google ScholarThere is no corresponding record for this reference.
- 473Clark, S. Eprovenance Tracks Wine Shipments with NFC. NFC World; 2011; http://www.nfcworld.com/2011/12/09/311852/eprovenance-tracks-wine-shipments-with-nfc/ (accessed July 27, 2016).Google ScholarThere is no corresponding record for this reference.
- 474Dyer, K. AMS Develops NFC Chip for Medical Implants. NFC World; 2013; http://www.nfcworld.com/2013/09/03/325679/ams-develops-nfc-chip-medical-implants/ (accessed July 27, 2016).Google ScholarThere is no corresponding record for this reference.
- 475Boden, R. Thinfilm Shows Printed NFC Smart Label with Temperature Sensor. NFC World; 2014; http://www.nfcworld.com/2014/05/28/329390/thinfilm-shows-printed-nfc-smart-label-temperature-sensor/ (accessed July 27, 2016).Google ScholarThere is no corresponding record for this reference.
- 476Rittersma, Z. M. Recent Achievements in Miniaturised Humidity Sensors - A Review of Transduction Techniques Sens. Actuators, A 2002, 96, 196– 210 DOI: 10.1016/S0924-4247(01)00788-9Google Scholar476https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD38XhvVCkt70%253D&md5=556c4029ee45c9c171e7335958533f38Recent achievements in miniaturised humidity sensors-a review of transduction techniquesRittersma, Z. M.Sensors and Actuators, A: Physical (2002), 96 (2-3), 196-210CODEN: SAAPEB; ISSN:0924-4247. (Elsevier Science S.A.)A review of miniaturized humidity sensors is presented. Recent achievements in capacitive, hygrometric, gravimetric, optical and integrated sensors are discussed. Attention is paid to a general perspective of miniaturized humidity sensors, emphasizing on integration issues and technol. challenges. A table summarizing most of the reviewed devices is included.
- 477Chen, Z.; Lu, C. Humidity Sensors: A Review of Materials and Mechanisms Sens. Lett. 2005, 3, 274– 295 DOI: 10.1166/sl.2005.045Google Scholar477https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD28XhtFagtb0%253D&md5=638c0b43154ce42aa4b72adb1e348821Humidity sensors: a review of materials and mechanismsChen, Zhi; Lu, ChiSensor Letters (2005), 3 (4), 274-295CODEN: SLEEA3; ISSN:1546-198X. (American Scientific Publishers)A review. The authors have reviewed humidity sensors based on various materials for both relative and abs. humidity, including ceramic, semiconducting, and polymer materials. In the majority of publications, there are few papers dealing with abs. humidity sensors, which have extensive applications in industry. The authors reviewed extensively abs. humidity sensors which is unique comparing with other reviews of humidity sensors. The elec. properties of humidity sensors such as sensitivity, response time, and stability were described in details for various materials and a considerable part of the review is focused on the sensing mechanisms. Prepn. and characterization of sensing materials are also described. For abs. humidity sensors, mirror-based dew-point sensors and solid-state Al2O3 moisture sensors were described. As the major problem in Al2O3 moisture sensors, long-term instability, was solved, α-Al2O3 moisture sensors may have promising future in industry.
- 478Lee, C. Y.; Lee, G. B. Humidity Sensors: A Review Sens. Lett. 2005, 3, 1– 15 DOI: 10.1166/sl.2005.001Google Scholar478https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD2MXlsFWqur0%253D&md5=d42c76ec473c3eeaeac10251085c7144Humidity sensors: a reviewLee, Chia-Yen; Lee, Gwo-BinSensor Letters (2005), 3 (1), 1-15CODEN: SLEEA3; ISSN:1546-198X. (American Scientific Publishers)A review. Humidity is one of the most commonly measured phys. quantities and is of great importance in a wide variety. This paper reviews the transduction techniques of various state-of-the-art humidity sensors, including (1) optical, (2) gravimetric, (3) capacitive, (4) resistive, (5) piezoresistive, and (6) magnetoelastic sensors. Starting from the fundamental operation principles, crit. issues about design, fabrication, characterization and applications of these humidity sensors were reviewed. It is notable that promising technologies was applied to revolutionize the design of the humidity sensors. Smaller, faster, cheaper humidity sensors were reported in the published literatures. However, it still remains challenging to develop a humidity sensor which provides a complete set of favorable characteristics, e.g., good linearity, high sensitivity, low hysteresis and rapid response time.
- 479Farahani, H.; Wagiran, R.; Hamidon, M. N. Humidity Sensors Principle, Mechanism, and Fabrication Technologies: A Comprehensive Review Sensors 2014, 14, 7881– 7939 DOI: 10.3390/s140507881Google Scholar479https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2cXhs1GjsbfL&md5=5724933d03973eb5b5a4dbc25906592aHumidity sensors principle, mechanism, and fabrication technologies: a comprehensive reviewFarahani, Hamid; Wagiran, Rahman; Hamidon, Mohd NizarSensors (2014), 14 (5), 7881-7939, 59 pp.CODEN: SENSC9; ISSN:1424-8220. (MDPI AG)A review. Humidity measurement is one of the most significant issues in various areas of applications such as instrumentation, automated systems, agriculture, climatol. and GIS. Numerous sorts of humidity sensors fabricated and developed for industrial and lab. applications are reviewed and presented in this article. The survey frequently concs. on the RH sensors based upon their org. and inorg. functional materials, e.g., porous ceramics (semiconductors), polymers, ceramic/polymer and electrolytes, as well as conduction mechanism and fabrication technologies. A significant aim of this review is to provide a distinct categorization pursuant to state of the art humidity sensor types, principles of work, sensing substances, transduction mechanisms, and prodn. technologies. Furthermore, performance characteristics of the different humidity sensors such as elec. and statistical data will be detailed and gives an added value to the report. By comparison of overall prospects of the sensors it was revealed that there are still drawbacks as to efficiency of sensing elements and conduction values. The flexibility offered by thick film and thin film processes either in the prepn. of materials or in the choice of shape and size of the sensor structure provides advantages over other technologies. These ceramic sensors show faster response than other types.
- 480Kaminski, E.; Stawicki, S.; Wasowicz, E. Volatile Flavor Compounds Produced by Molds of Aspergillus, Penicillium, and Fungi Imperfecti Appl. Microbiol. 1974, 27, 1001– 1004Google Scholar480https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADyaE2cXltVent7k%253D&md5=c04c86c00ac7836f7ce8ea7e5286e449Volatile flavor compounds produced by molds of Aspergillus, Penicillium, and Fungi imperfectiKaminski, E.; Stawicki, S.; Wasowicz, E.Applied Microbiology (1974), 27 (6), 1001-4CODEN: APMBAY; ISSN:0003-6919.Volatile compds. from cultures of Aspergillus niger, A. ochraceus, A. oryzae, A. parasiticus, Penicillium chrysogenum, P. citrinum, P. funiculosum, P. raistrickii, P. viridicatum, Alternaria, Cephalosporium, and Fusarium were sepd. and identified by gas chromatog., mass spectroscopy, and chem. tests. 3-Methylbutanol, 3-octanone, 3-octanol, 1-octen-3-ol, 1-octanol, and 2-octen-1-ol were identified pos. and represented 67-97% of all the volatiles isolated by low temp.-reduced pressure distn. Octane, isobutyl alc., BuOH, BuOAc, amyl acetate, octyl acetate, pyridine, hexanol, nonanone, dimethylpyrazine, tetramethylpyrazine, PhCHO, PhPr and phenethyl alc. were tentatively identified.
- 481Bartley, J. P.; Schwede, A. M. Production of Volatile Compounds in Ripening Kiwi Fruit (Actinidia Chinensis) J. Agric. Food Chem. 1989, 37, 1023– 1025 DOI: 10.1021/jf00088a046Google ScholarThere is no corresponding record for this reference.
- 482Song, J.; Fan, L.; Beaudry, R. M. Application of Solid Phase Microextraction and Gas Chromatography/Time-of-Flight Mass Spectrometry for Rapid Analysis of Flavor Volatiles in Tomato and Strawberry Fruits J. Agric. Food Chem. 1998, 46, 3721– 3726 DOI: 10.1021/jf980214oGoogle Scholar482https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADyaK1cXltV2rs7g%253D&md5=fcbb148a8a5ca4f41f2917e9e9aed1b9Application of Solid Phase Microextraction and Gas Chromatography/Time-of-Flight Mass Spectrometry for Rapid Analysis of Flavor Volatiles in Tomato and Strawberry FruitsSong, Jun; Fan, Lihua; Beaudry, Randolph M.Journal of Agricultural and Food Chemistry (1998), 46 (9), 3721-3726CODEN: JAFCAU; ISSN:0021-8561. (American Chemical Society)Solid phase microextn. (SPME), a relatively new sampling technique, was examd. as a means to investigate volatile compds. produced by tomato (Lycopersicon esculentum Mill.) and strawberry (Fragaria × ananassa Duch.) fruit. SPME had sufficient sorptive capacity to permit detection of aroma compds. having a variety of functional groups. The advantages of using SPME were its simplicity, absence of solvent, and speed. Fiber cleaning, sample collection, and desorption required ∼6 min. The total anal. time was ∼10 min per sample when SPME was combined with rapid gas chromatog. (GC) sepn. and time-of-flight mass spectrometry (TOFMS). The major volatile compds. detected from tomato and strawberry and their relative abundance were comparable with published results from purge-and-trap/GC/FID analyses. One of the primary flavor impact compds. in strawberry, 2,5-dimethyl-4-methoxy-3(2H)-furanone was detected by using SPME/GC/TOFMS. SPME appears to be suitable for rapid and quant. anal. of volatile aroma compds. in tomato and strawberry fruit.
- 483Jordán, M. J.; Tandon, K.; Shaw, P. E.; Goodner, K. L. Aromatic Profile of Aqueous Banana Essence and Banana Fruit by Gas Chromatography-Mass Spectrometry (GC-MS) and Gas Chromatography-Olfactometry (GC-O) J. Agric. Food Chem. 2001, 49, 4813– 4817 DOI: 10.1021/jf010471kGoogle ScholarThere is no corresponding record for this reference.
- 484Martini, A. M.; Budai, J. M.; Walter, L. M.; Schoell, M. Microbial Generation of Economic Accumulations of Methane within a Shallow Organic-Rich Shale Nature 1996, 383, 155– 158 DOI: 10.1038/383155a0Google Scholar484https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADyaK28Xls12rtr0%253D&md5=d504f6442f9bed73d17d0a14f0994445Microbial generation of economic accumulations of methane within a shallow organic-rich shaleMartini, Anna M.; Budai, Joyce M.; Walter, Lynn M.; Schoell, MartinNature (London) (1996), 383 (6596), 155-158CODEN: NATUAS; ISSN:0028-0836. (Macmillan Magazines)Although methane of bacterial origin is ubiquitous in marine and freshwater sediments, economic accumulations of bacterial gases occur mainly at depths of several kilometers in Tertiary basins that had high sedimentation rates. An integration of geochem. and isotopic data is presented from gas and water extd. from the Upper Devonian Antrim shale, along the northern margin of the Michigan basin; the data demonstrates that significant vols. of bacterial gas have been generated in org.-rich shales at depths of less than 600 m. The Antrim shale is mainly a self-sourced reservoir, in contrast to conventional gas deposits that have migrated from a source to a reservoir, and has become one of the most actively exploited gas reservoirs in the United States. The gas-forming processes operating at shallow depths in the Antrim shale are not unique, and an understanding of these processes should lead to the identification and development of other economic, nonconventional gas deposits around the world.
- 485Smart, K. F.; Aggio, R. B. M.; Van Houtte, J. R.; Villas-Bôas, S. G. Analytical Platform for Metabolome Analysis of Microbial Cells Using Methyl Chloroformate Derivatization Followed by Gas Chromatography-Mass Spectrometry Nat. Protoc. 2010, 5, 1709– 1729 DOI: 10.1038/nprot.2010.108Google Scholar485https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC3cXht1agsbbF&md5=91764d86341bf6b825359ed2080026baAnalytical platform for metabolome analysis of microbial cells using methyl chloroformate derivatization followed by gas chromatography-mass spectrometrySmart, Kathleen F.; Aggio, Raphael B. M.; Van Houtte, Jeremy R.; Villas-Boas, Silas G.Nature Protocols (2010), 5 (10), 1709-1729CODEN: NPARDW; ISSN:1750-2799. (Nature Publishing Group)A review. This protocol describes an anal. platform for the anal. of intra- and extracellular metabolites of microbial cells (yeast, filamentous fungi and bacteria) using gas chromatog.-mass spectrometry (GC-MS). The protocol is subdivided into sampling, sample prepn., chem. derivatization of metabolites, GC-MS anal. and data processing and anal. This protocol uses two robust quenching methods for microbial cultures, the first of which, cold glycerol-saline quenching, causes reduced leakage of intracellular metabolites, thus allowing a more reliable sepn. of intra- and extracellular metabolites with simultaneous stopping of cell metab. The second, fast filtration, is specifically designed for quenching filamentous micro-organisms. These sampling techniques are combined with an easy sample-prepn. procedure and a fast chem. derivatization reaction using Me chloroformate. This reaction takes place at room temp., in aq. medium, and is less prone to matrix effect compared with other derivatizations. This protocol takes an av. of 10 d to complete and enables the simultaneous anal. of hundreds of metabolites from the central carbon metab. (amino and nonamino org. acids, phosphorylated org. acids and fatty acid intermediates) using an inhouse MS library and a data anal. pipeline consisting of two free software programs (Automated Mass Deconvolution and Identification System (AMDIS) and R).
- 486Scholten, K.; Collin, W. R.; Fan, X.; Zellers, E. T. Nanoparticle-Coated Micro-Optofluidic Ring Resonator as a Detector for Microscale Gas Chromatographic Vapor Analysis Nanoscale 2015, 7, 9282– 9289 DOI: 10.1039/C5NR01780GGoogle Scholar486https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2MXntFSqtb0%253D&md5=8df56ddf31a87c1888a81c9db1557ef8Nanoparticle-coated micro-optofluidic ring resonator as a detector for microscale gas chromatographic vapor analysisScholten, K.; Collin, W. R.; Fan, X.; Zellers, E. T.Nanoscale (2015), 7 (20), 9282-9289CODEN: NANOHL; ISSN:2040-3372. (Royal Society of Chemistry)A vapor sensor comprising a nanoparticle-coated microfabricated optofluidic ring resonator (μOFRR) is introduced. A multilayer film of polyether functionalized, thiolate-monolayer-protected gold nanoparticles (MPN) was solvent cast on the inner wall of the hollow cylindrical SiOx μOFRR resonator structure, and whispering gallery mode (WGM) resonances were generated with a 1550 nm tunable laser via an optical fiber taper. Reversible shifts in the WGM resonant wavelength upon vapor exposure were detected with a photodetector. The μOFRR chip was connected to a pair of upstream etched-Si chips contg. PDMS-coated sepn. μcolumns and calibration curves were generated from the peak-area responses to five volatile org. compds. (VOCs). Calibration curves were linear, and the sensitivities reflected the influence of analyte volatility and analyte-MPN functional group affinity. Sorption-induced changes in film thickness apparently dominate over changes in the refractive index of the film as the determinant of responses for all VOCs. Peaks from the MPN-coated μOFRR were just 20-50% wider than those from a flame ionization detector for similar μcolumn sepn. conditions, reflecting the rapid response of the sensor for VOCs. The five VOCs were baseline sepd. in <1.67 min, with detection limits as low as 38 ng.
- 487Chen, C. H.; Chen, T. C.; Zhou, X.; Kline-Schoder, R.; Sorensen, P.; Cooks, R. G.; Ouyang, Z. Design of Portable Mass Spectrometers with Handheld Probes: Aspects of the Sampling and Miniature Pumping Systems J. Am. Soc. Mass Spectrom. 2015, 26, 240– 247 DOI: 10.1007/s13361-014-1026-5Google Scholar487https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2cXhvFOhtLrK&md5=067b45032b6fe588fec30de29b29d797Design of Portable Mass Spectrometers with Handheld Probes: Aspects of the Sampling and Miniature Pumping SystemsChen, Chien-Hsun; Chen, Tsung-Chi; Zhou, Xiaoyu; Kline-Schoder, Robert; Sorensen, Paul; Cooks, R. Graham; Ouyang, ZhengJournal of the American Society for Mass Spectrometry (2015), 26 (2), 240-247CODEN: JAMSEF; ISSN:1044-0305. (Springer)Miniature mass spectrometry anal. systems of backpack configuration fitted with sampling probes could potentially be of significant interest for in-field, real-time chem. anal. Various configurations were explored in which a long narrow tube was used to connect the turbo and backing pumps used to create and maintain vacuum. Also, for the 1st time the authors introduced two new types of pumps for miniature mass spectrometers, the Creare 130 g drag pump and Creare 350 g scroll backing pump. These pumps, along with another Creare 550 turbo pump and the com. available Pfeiffer HiPace 10 turbo and KnF diaphragm backing pumps, were tested with the backpack configurations. The system performance, esp. the scan time, was characterized when used with a discontinuous atm. pressure interface (DAPI) for ion introduction. The pumping performance in the pressure region >1 mtorr is crit. for DAPI operation. The 550 g turbo pump has a relatively higher pumping speed >1 mtorr and gave a scan time of 300 ms, almost half the value obtained with the larger, heavier HiPace 10 often used with miniature mass spectrometers. The 350 g scroll pump also is an improvement over the diaphragm pumps generally used as backing pumps. With a coaxial low temp. plasma ion source, direct anal. of low volatility compds. glass slides was demonstrated, including 1 ng DNP (2,4-Dinitrophenol) and 10 ng TNT (2,4,6-trinitrotoluene) with Creare 550 g turbo pump as well as 10 ng cocaine and 20 ng DNP with Creare 130 g drag pump.
- 488Szabadváry, F. History of Analytical Chemistry; Pergamon Press: Oxford, U.K., 1966.Google ScholarThere is no corresponding record for this reference.
- 489Wallace, L. A.; Ott, W. R. Personal Monitors: A State-of-the-Art Survey J. Air Pollut. Control Assoc. 1982, 32, 601– 610 DOI: 10.1080/00022470.1982.10465435Google Scholar489https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADyaL38XksVegs7k%253D&md5=0c0c21a2cfd91043335f79c97f97f477Personal monitors: a state-of-the-art surveyWallace, Lance A.; Ott, Wayne R.Journal of the Air Pollution Control Association (1982), 32 (6), 601-10CODEN: JPCAAC; ISSN:0002-2470.A review with 69 refs.
- 490Gerber, L. C.; Rosenfeld, L.; Chen, Y.; Tang, S. K. Y. Time Capsule: An Autonomous Sensor and Recorder Based on Diffusion-Reaction Lab Chip 2014, 14, 4324– 4328 DOI: 10.1039/C4LC00640BGoogle Scholar490https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2cXhsVCjtLbE&md5=674ed0f1d1a3c4cc3fb5497a134da5d6Time capsule: an autonomous sensor and recorder based on diffusion-reactionGerber, Lukas C.; Rosenfeld, Liat; Chen, Yunhan; Tang, Sindy K. Y.Lab on a Chip (2014), 14 (22), 4324-4328CODEN: LCAHAM; ISSN:1473-0189. (Royal Society of Chemistry)We describe the use of chem. diffusion and reaction to record temporally varying chem. information as spatial patterns without the need for external power. Diffusion of chems. acts as a clock, while reactions forming immobile products possessing defined optical properties perform sensing and recording functions simultaneously. The spatial location of the products reflects the history of exposure to the detected substances of interest. We refer to our device as a time capsule and show an initial proof of principle in the autonomous detection of lead ions in water.
- 491Claramunt, S.; Monereo, O.; Boix, M.; Leghrib, R.; Prades, J. D.; Cornet, A.; Merino, P.; Merino, C.; Cirera, A. Flexible Gas Sensor Array with an Embedded Heater Based on Metal Decorated Carbon Nanofibres Sens. Actuators, B 2013, 187, 401– 406 DOI: 10.1016/j.snb.2012.12.093Google Scholar491https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC3sXhtF2it7s%253D&md5=b02e6d468838164c982be247ce9f4559Flexible gas sensor array with an embedded heater based on metal decorated carbon nanofibersClaramunt, S.; Monereo, O.; Boix, M.; Leghrib, R.; Prades, J. D.; Cornet, A.; Merino, P.; Merino, C.; Cirera, A.Sensors and Actuators, B: Chemical (2013), 187 (), 401-406CODEN: SABCEB; ISSN:0925-4005. (Elsevier B.V.)Carbon nanofibres decorated with metal nanoparticles were deposited over kapton, a polyimide flexible substrate, onto which array interdigitated electrodes in one side and a common heater in the backside were printed using inkjet printing technique. The control over metal type (as-grown, Au, Pd) and the decoration percentage gave us the possibility to improve the sensors response, and also enhance the selectivity by taking advantage of the different interaction behaviors of tested target gas mols. with different hybrid materials that occur at room temp.
- 492Choi, H.; Choi, J. S.; Kim, J.-S.; Choe, J.-H.; Chung, K. H.; Shin, J.-W.; Kim, J. T.; Youn, D.-H.; Kim, K.-C.; Lee, J.-I.; Choi, S.-Y.; Kim, P.; Choi, C.-G.; Yu, Y.-J. Flexible and Transparent Gas Molecule Sensor Integrated with Sensing and Heating Graphene Layers Small 2014, 10, 3685– 3691 DOI: 10.1002/smll.201400434Google Scholar492https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2cXotVyrt7o%253D&md5=8cf72eb6beb702d0e3526aac30248945Flexible and Transparent Gas Molecule Sensor Integrated with Sensing and Heating Graphene LayersChoi, Hongkyw; Choi, Jin Sik; Kim, Jin-Soo; Choe, Jong-Ho; Chung, Kwang Hyo; Shin, Jin-Wook; Kim, Jin Tae; Youn, Doo-Hyeb; Kim, Ki-Chul; Lee, Jeong-Ik; Choi, Sung-Yool; Kim, Philip; Choi, Choon-Gi; Yu, Young-JunSmall (2014), 10 (18), 3685-3691CODEN: SMALBC; ISSN:1613-6810. (Wiley-VCH Verlag GmbH & Co. KGaA)Graphene leading to high surface-to-vol. ratio and outstanding cond. is applied for gas mol. sensing with fully using its unique transparent and flexible functionalities which cannot be expected from solid-state gas sensors. To attain a fast response and rapid recovering time, the flexible sensors also require integrated flexible and transparent heaters. Here, large-scale flexible and transparent gas mol. sensor devices, integrated with a graphene sensing channel and a graphene transparent heater for fast recovering operation, are demonstrated. This combined all-graphene device structure enables an overall device optical transmittance that exceeds 90% and reliable sensing performance with a bending strain of <1.4%. In particular, it is possible to classify the fast (≈14 s) and slow (≈95 s) response due to sp2-carbon bonding and disorders on graphene and the self-integrated graphene heater leads to the rapid recovery (≈11 s) of a 2. cm × 2 cm sized sensor with reproducible sensing cycles, including full recovery steps without significant signal degrdn. under exposure to NO2 gas.
- 493Zhang, C.; Boudiba, A.; De Marco, P.; Snyders, R.; Olivier, M.-G.; Debliquy, M. Room Temperature Responses of Visible-Light Illuminated WO3 Sensors to NO2 in Sub-ppm Range Sens. Actuators, B 2013, 181, 395– 401 DOI: 10.1016/j.snb.2013.01.082Google Scholar493https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC3sXlt1Chs7c%253D&md5=cd77e40c1e8dd2af5275fad6a74ac595Room temperature responses of visible-light illuminated WO3 sensors to NO2 in sub-ppm rangeZhang, Chao; Boudiba, Abdelhamid; De Marco, Patrizia; Snyders, Rony; Olivier, Marie-Georges; Debliquy, MarcSensors and Actuators, B: Chemical (2013), 181 (), 395-401CODEN: SABCEB; ISSN:0925-4005. (Elsevier B.V.)The effects of visible-light illumination on sensing properties of WO3 sensors were investigated. WO3 sensitive films are prepd. on alumina substrates by screen-printing. WO3 sensors illuminated by visible/ultra-violet lights are submitted to sensing tests with 160 and 320 ppb NO2 at room temp. NO2 sensing characteristics of the WO3 sensor are significantly improved by illumination as compared to that in the dark. Influences of light wavelength and light intensity on the sensing characteristics are further studied. Visible light can effectively activate the WO3 sensors and blue light is a good choice to produce room-temp. devices which are suited for NO2 sensing applications. A sensing mechanism is proposed according to a simple adsorption-photodesorption model.
- 494Pizzoni, D.; Mascini, M.; Lanzone, V.; Del Carlo, M.; Di Natale, C.; Compagnone, D. Selection of Peptide Ligands for Piezoelectric Peptide Based Gas Sensors Arrays Using a Virtual Screening Approach Biosens. Bioelectron. 2014, 52, 247– 254 DOI: 10.1016/j.bios.2013.08.044Google ScholarThere is no corresponding record for this reference.
- 495Loschen, C.; Klamt, A. Prediction of Solubilities and Partition Coefficients in Polymers Using COSMO-RS Ind. Eng. Chem. Res. 2014, 53, 11478– 11487 DOI: 10.1021/ie501669zGoogle Scholar495https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2cXps1eqtb4%253D&md5=6ccf202c59302925df431b7dae121741Prediction of Solubilities and Partition Coefficients in Polymers Using COSMO-RSLoschen, Christoph; Klamt, AndreasIndustrial & Engineering Chemistry Research (2014), 53 (28), 11478-11487CODEN: IECRED; ISSN:0888-5885. (American Chemical Society)Recent results concerning the prediction of thermodn. properties of solutes in polymers are presented. In particular, the computation of vapor-liq. and gas-liq. equil. (i.e., liq. and gas solubilities) in different polymers and partition coeffs. between the polymer and a solvent phase are addressed. Calcns. have been carried out using COSMO-RS theory which combines quantum-chem. calcns. with efficient statistical thermodn. for intermol. interactions. Predictions for vapor-liq. equil. and for partition coeffs. have been improved by incorporation of polymer-specific entropic contributions due to free vol. effects. It is demonstrated that a high predictive accuracy is obtained if the polymer is sufficiently characterized by its compn., d., and crystallinity. The approach is currently limited to gaseous and liq. solutes and to linear, i.e. non-cross-linked polymers without any significant swelling.
- 496Hertz, J. L.; Lahr, D. L.; Semancik, S. Combinatorial Characterization of Chemiresistive Films Using Microhotplates IEEE Sens. J. 2012, 12, 1459– 1460 DOI: 10.1109/JSEN.2011.2173673Google Scholar496https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC38XpsFOhtr8%253D&md5=9de4b67c672a5d58f03e5e7bdd1198deCombinatorial characterization of chemiresistive films using microhotplatesHertz, Joshua L.; Lahr, David L.; Semancik, SteveIEEE Sensors Journal (2012), 12 (5), 1459-1460CODEN: ISJEAZ; ISSN:1530-437X. (Institute of Electrical and Electronics Engineers)When producing chem. sensors, esp. in thin film form, there are often a large variety of processing variables that are believed to impact the ultimate performance of the materials. It is thus advantageous to find methods for simultaneous, high-throughput characterization of many process variables. Here, we report on a method for using MEMS-based microhotplates to create and characterize arrays of chemiresistive SnO2 thin films. The microhotplates are used both to control the thermal process variables at each element of the array during film growth by CVD as well as subsequently to operate the sensors. Example chemiresistive properties of the films at 200 °C were characterized during exposure to CH3 OH and NO2. Through the use of a fractional factorial expt. design, the effects of 4 different process variables (growth temp., thickness, presence of a dopant and use of rapidly pulsed heating during growth) were reliably detd. using only 8 films and the assocd. statistical modeling of the results.
- 497Belle, C. J.; Simon, U. High-Throughput Experimentation in Resistive Gas Sensor Materials Development J. Mater. Res. 2013, 28, 574– 588 DOI: 10.1557/jmr.2012.344Google Scholar497https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC3sXjt1CntLk%253D&md5=470ec4c25e4e4078f190737b7b1ab17eHigh-throughput experimentation in resistive gas sensor materials developmentBelle, Clemens J.; Simon, UlrichJournal of Materials Research (2013), 28 (4), 574-588CODEN: JMREEE; ISSN:0884-1616. (Cambridge University Press)The review describes the work-flow of a high-throughput screening process for the rapid identification of new and improved gas sensor materials. Multiple nanoparticulate metal oxides were prepd. via the polyol method, and material diversity was achieved by vol. and/or surface doping. The resulting materials were applied as thick films on multielectrode substrates to serve as chemiresistors. This high-throughput approach including automated prepn., complex impedance measurements, and evaluation procedures enables reproducible measurements and their visual representation. Selected examples demonstrate the state of the art for applying high-throughput in search of new sensitive and selective gas sensing materials as well as in analyzing structure-property relations.
- 498Zhao, Y.; Zhang, S.; Zhang, G.; Deng, X.; Xie, C. Highly Sensitive Porous Metal Oxide Films for Early Detection of Electrical Fire: Surface Modification and High Throughput Screening Sens. Actuators, B 2014, 191, 431– 437 DOI: 10.1016/j.snb.2013.09.111Google Scholar498https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC3sXhvFWrsrrL&md5=7fe8b2443ecc6179e84cdaf05d46d8efHighly sensitive porous metal oxide films for early detection of electrical fire: Surface modification and high throughput screeningZhao, Ye; Zhang, Shunping; Zhang, Guozhu; Deng, Xiaoshuang; Xie, ChangshengSensors and Actuators, B: Chemical (2014), 191 (), 431-437CODEN: SABCEB; ISSN:0925-4005. (Elsevier B.V.)In this study, an elec. fire simulator was fabricated and connected to a test platform which can take high throughput screening of materials through the method of combinatorial material science. WO3 and In2O3 were used as basis materials in the expt. and modified through the way of micro-injection in order to find the best one sensitive to elec. fire. It is found that CrCl3-modified and MgCl2-modified WO3, as well as LaOCl-modified and SmOCl-modified In2O3 show the best sensing performance. They can be used as sensitive materials for early detection of elec. fire because they have good sensitivity to the smell of PVC even if the working temp. of PVC insulated wires is lower than 200 !!!C. Therefore, it confirms that the early detection of elec. fire in the invisible smoke stage is feasible by using the modified WO3 or In2O3.
- 499MacNaughton, S.; Ammu, S.; Manohar, S. K.; Sonkusale, S. High-Throughput Heterogeneous Integration of Diverse Nanomaterials on a Single Chip for Sensing Applications PLoS One 2014, 9, e111377 DOI: 10.1371/journal.pone.0111377Google ScholarThere is no corresponding record for this reference.
- 500Zhang, G.; Xie, C.; Zhang, S.; Zhao, J.; Lei, T.; Zeng, D. Temperature-Programmed Technique Accompanied with Highthroughput Methodology for Rapidly Searching the Optimal Operating Temperature of MOX Gas Sensors ACS Comb. Sci. 2014, 16, 459– 465 DOI: 10.1021/co500054rGoogle Scholar500https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2cXht1Kmsb7M&md5=b2864df463ef3df6dcd12e80e1ee8fcdTemperature-Programmed Technique Accompanied with High-Throughput Methodology for Rapidly Searching the Optimal Operating Temperature of MOX Gas SensorsZhang, Guozhu; Xie, Changsheng; Zhang, Shunping; Zhao, Jianwei; Lei, Tao; Zeng, DawenACS Combinatorial Science (2014), 16 (9), 459-465CODEN: ACSCCC; ISSN:2156-8944. (American Chemical Society)A combinatorial high-throughput temp.-programmed method to obtain the optimal operating temp. (OOT) of gas sensor materials is demonstrated here for the 1st time. A material library consisting of SnO2, ZnO, WO3, and In2O3 sensor films was fabricated by screen printing. Temp.-dependent cond. curves were obtained by scanning this gas sensor library from 300 to 700 K in different atms. (dry air, formaldehyde, carbon monoxide, nitrogen dioxide, toluene and ammonia), giving the OOT of each sensor formulation as a function of the carrier and analyte gases. A comparative study of the temp.-programmed method and a conventional method showed good agreement in measured OOT.
- 501Hubble, L. J.; Cooper, J. S.; Sosa-Pintos, A.; Kiiveri, H.; Chow, E.; Webster, M. S.; Wieczorek, L.; Raguse, B. High-Throughput Fabrication and Screening Improves Gold Nanoparticle Chemiresistor Sensor Performance ACS Comb. Sci. 2015, 17, 120– 129 DOI: 10.1021/co500129vGoogle Scholar501https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2MXltVWmug%253D%253D&md5=2c0c56e2cc9d6afdd842c70a53c56d09High-Throughput Fabrication and Screening Improves Gold Nanoparticle Chemiresistor Sensor PerformanceHubble, Lee J.; Cooper, James S.; Sosa-Pintos, Andrea; Kiiveri, Harri; Chow, Edith; Webster, Melissa S.; Wieczorek, Lech; Raguse, BurkhardACS Combinatorial Science (2015), 17 (2), 120-129CODEN: ACSCCC; ISSN:2156-8944. (American Chemical Society)Chemiresistor sensor arrays are a promising technol. to replace current lab.-based anal. instrumentation, with the advantage of facile integration into portable, low-cost devices for in-field use. To increase the performance of chemiresistor sensor arrays a high-throughput fabrication and screening methodol. was developed to assess different organothiol-functionalized gold nanoparticle chemiresistors. This high-throughput fabrication and testing methodol. was implemented to screen a library consisting of 132 different organothiol compds. as capping agents for functionalized gold nanoparticle chemiresistor sensors. The methodol. used an automated liq. handling workstation for the in situ functionalization of gold nanoparticle films and subsequent automated analyte testing of sensor arrays using a flow-injection anal. system. To test the methodol. the authors focused on the discrimination and quantitation of benzene, toluene, ethylbenzene, p-xylene, and naphthalene (BTEXN) mixts. in water at low microgram per L concn. levels. The high-throughput methodol. identified a sensor array configuration consisting of a subset of organothiol-functionalized chemiresistors which in combination with random forests anal. was able to predict individual analyte concns. with overall root-mean-square errors ranging between 8-17 μg/L for mixts. of BTEXN in water at the 100 μg/L concn. The ability to use a simple sensor array system to quantitate BTEXN mixts. in water at the low μg/L concn. range has direct and significant implications to future environmental monitoring and reporting strategies. These results demonstrate the advantages of high-throughput screening to improve the performance of gold nanoparticle based chemiresistors for both new and existing applications.
- 502Deng, Y.; Chen, C.; Qin, X.; Xian, X.; Alford, T. L.; Choi, H. W.; Tsow, F.; Forzani, E. S. Aging Effect of a Molecularly Imprinted Polymer on a Quartz Tuning Fork Sensor for Detection of Volatile Organic Compounds Sens. Actuators, B 2015, 211, 25– 32 DOI: 10.1016/j.snb.2015.01.068Google Scholar502https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2MXhvFSitLw%253D&md5=d9bf802d683d483a942be522a251b423Aging effect of a molecularly imprinted polymer on a quartz tuning fork sensor for detection of volatile organic compoundsDeng, Yue; Chen, Cheng; Qin, Xingcai; Xian, Xiaojun; Alford, Terry L.; Choi, Hyung W.; Tsow, Francis; Forzani, Erica S.Sensors and Actuators, B: Chemical (2015), 211 (), 25-32CODEN: SABCEB; ISSN:0925-4005. (Elsevier B.V.)The sensing stability and sensitivity of a molecularly imprinted polymer (MIP) selective to the adsorption of hydrocarbons was studied. The MIP was deposited on a quartz crystal tuning fork (QTF) resonator, whose chem. and phys. properties were monitored over time, using SEM (SEM), Brunauer-Emmett-Teller adsorption isotherm anal. (BET), and Fourier transform IR spectroscopy (FTIR). In addn., kinetic binding anal. of the MIP-modified QTF sensor was carried out for the sensors stored and operated under ambient conditions (740 mmHg, 20-23 °C). Although the polymer was able to maintain its phys. and chem. properties at microscopic, BET adsorption, and spectroscopic levels, the intrinsic adsorption properties of hydrocarbons onto MIP binding sites altered over time, which suggest that the 3-D conformational changes of the polymer binding sites occurring at nanoscopic/angstrom level may cause the sensitivity degrdn. in MIP. The changes were significantly reduced by stabilizing the polymer under low storage temps.
- 503Lazzerini, G. M.; Strambini, L. M.; Barillaro, G. Addressing Reliability and Degradation of Chemitransistor Sensors by Electrical Tuning of the Sensitivity Sci. Rep. 2013, 3, 1161 DOI: 10.1038/srep01161Google Scholar503https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC3sXpvFWhurk%253D&md5=7d13af341c4573a2e358642902ea73f7Addressing reliability and degradation of chemitransistor sensors by electrical tuning of the sensitivityLazzerini, G. M.; Strambini, L. M.; Barillaro, G.Scientific Reports (2013), 3 (), 1161, 8 pp.CODEN: SRCEC3; ISSN:2045-2322. (Nature Publishing Group)Here we show that elec. tuning of the sensitivity of chemitransistor sensors, namely field-effect-transistors (FETs) exploiting nano/mesostructured sensing materials, can be used to effectively address two chief problems of state-of-the-art gas sensors, specifically fabrication reliability and degrdn. by aging. Both exptl. evidences and theor. calcns. are provided to support such a result, using as a case-of-study junction field-effect-transistors (JFETs) exploiting mesostructured porous silicon (PS) as sensing material (PSJFETs) for the detection of nitrogen dioxide (NO2) at hundreds ppb. Proof of concept is given by fully compensating the effect of fabrication errors on the sensitivity of two PSJFETs integrated on the same chip, which, though identical in principle, feature sensitivities to NO2 differing from about 30% before compensation. Although here-demonstrated for the specific case of PSJFETs, the concept of sensor reliability/aging problem compensation by sensitivity elec.-tuning can be applied to other chemitransistor sensors that exploit sensing materials different than PS.
- 504Strohfeldt, N.; Tittl, A.; Giessen, H. Long-Term Stability of Capped and Buffered Palladium-Nickel Thin Films and Nanostructures for Plasmonic Hydrogen Sensing Applications Opt. Mater. Express 2013, 3, 194– 204 DOI: 10.1364/OME.3.000194Google Scholar504https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC3sXjtVSrur4%253D&md5=e36840d28a1b85231fa18828f0f2d1dcLong-term stability of capped and buffered palladium-nickel thin films and nanostructures for plasmonic hydrogen sensing applicationsStrohfeldt, Nikolai; Tittl, Andreas; Giessen, HaraldOptical Materials Express (2013), 3 (2), 194-204CODEN: OMEPAX; ISSN:2159-3930. (Optical Society of America)One of the main challenges in optical hydrogen sensing is the stability of the sensor material. An optimized material combination for fast and reliable optical Pd-based hydrogen sensing devices was found and studied. It consists of a Pd-Ni alloy that is buffered by CaF2 and capped with a very thin layer of Pt. The system shows response times <10 s and almost no short-term aging effects. Furthermore, this optimized material system was incorporated into plasmonic nanostructures, laying the foundation for a stable and sensitive H2 detector.
- 505Filipovic, L.; Selberherr, S. Performance and Stress Analysis of Metal Oxide Films for CMOS-Integrated Gas Sensors Sensors 2015, 15, 7206– 7227 DOI: 10.3390/s150407206Google Scholar505https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2MXmvFChtrY%253D&md5=6be466e91bdcdf1a9d488d64ab156955Performance and stress analysis of metal oxide films for CMOS-integrated gas sensorsFilipovic, Lado; Selberherr, SiegfriedSensors (2015), 15 (4), 7206-7227CODEN: SENSC9; ISSN:1424-8220. (MDPI AG)The integration of gas sensor components into smart phones, tablets and wrist watches will revolutionize the environmental health and safety industry by providing individuals the ability to detect harmful chems. and pollutants in the environment using always-on hand-held or wearable devices. Metal oxide gas sensors rely on changes in their elec. conductance due to the interaction of the oxide with a surrounding gas. These sensors have been extensively studied in the hopes that they will provide full gas sensing functionality with CMOS integrability. The performance of several metal oxide materials, such as tin oxide (SnO2), zinc oxide (ZnO), indium oxide (In2O3) and indium-tin-oxide (ITO), are studied for the detection of various harmful or toxic cases. Due to the need for these films to be heated to temps. between 250°C and 550°C during operation in order to increase their sensing functionality, a considerable degrdn. of the film can result. The stress generation during thin film deposition and the thermo-mech. stress that arises during post-deposition cooling is analyzed through simulations. A tin oxide thin film is deposited using the efficient and economical spray pyrolysis technique, which involves three steps: the atomization of the precursor soln., the transport of the aerosol droplets towards the wafer and the decompn. of the precursor at or near the substrate resulting in film growth. The details of this technique and a simulation methodol. are presented. The dependence of the deposition technique on the sensor performance is also discussed.
- 506Lee, J.; Chang, H. T.; An, H.; Ahn, S.; Shim, J.; Kim, J. M. A Protective Layer Approach to Solvatochromic Sensors Nat. Commun. 2013, 4, 2461 DOI: 10.1038/ncomms3461Google Scholar506https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A280%3ADC%252BC3sbntl2ntQ%253D%253D&md5=34be138af52bf7e8fb710d39e95988b5A protective layer approach to solvatochromic sensorsLee Jung; Chang Hyun Taek; An Hyosung; Ahn Sora; Shim Jina; Kim Jong-ManNature communications (2013), 4 (), 2461 ISSN:.As they have been designed to undergo colorimetric changes that are dependent on the polarity of solvents, the majority of conventional solvatochromic molecule based sensor systems inevitably display broad overlaps in their absorption and emission bands. As a result, colorimetric differentiation of solvents of similar polarity has been extremely difficult. Here we present a tailor-made colorimetric and fluorescence turn-on type solvatochromic sensor that enables facile identification of a specific solvent. The sensor system displays a colorimetric transition only when a thin protective layer, which protects the solvatochromic materials, is destroyed or disrupted by a specific solvent. The versatility of the strategy is demonstrated by designing a sensor that differentiates chloroform and dichloromethane colorimetrically and one that performs sequence selective colorimetric sensing. In addition, the approach is employed to construct a solvatochromic molecular AND logic gate. The new strategy could open new avenues for the development of novel solvatochromic sensors.
- 507Chromaid Scanner; 2013; http://www.visualant.net/resources/Visualant_ChromaID_Datasheet.pdf (accessed July 27, 2016) .Google ScholarThere is no corresponding record for this reference.
- 508Hamamatsu Micro-Spectrometer C12666MA; 2016; http://www.hamamatsu.com/resources/pdf/ssd/c12666ma_kacc1216e.pdf (accessed July 27, 2016).Google ScholarThere is no corresponding record for this reference.
- 509Lighting Passport the World’s First Smart Handheld Spectrometer; 2016; http://www.lightingpassport.com/ (accessed July 27, 2016).Google ScholarThere is no corresponding record for this reference.
- 510Wang, X.; Gartia, M. R.; Jiang, J.; Chang, T. W.; Qian, J.; Liu, Y.; Liu, X.; Liu, G. L. Audio Jack Based Miniaturized Mobile Phone Electrochemical Sensing Platform Sens. Actuators, B 2015, 209, 677– 685 DOI: 10.1016/j.snb.2014.12.017Google Scholar510https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2MXhslOqsg%253D%253D&md5=2bd7d701059a4d3f0328a9cce7a8f6b8Audio jack based miniaturized mobile phone electrochemical sensing platformWang, Xinhao; Gartia, Manas Ranjan; Jiang, Jing; Chang, Te-Wei; Qian, Junle; Liu, Yong; Liu, Xiangrong; Liu, Gang LoganSensors and Actuators, B: Chemical (2015), 209 (), 677-685CODEN: SABCEB; ISSN:0925-4005. (Elsevier B.V.)We demonstrated a mobile phone sensing platform, MoboSens, with integrated plug-n-play microelectronic ionic sensor that performs electrochem. measurement by using audio jack of a smartphone. This platform was used to measure nitrate concn. using few microliter liq. samples on field along with providing geospatial map locations through wireless network. This compact MoboSens platform (∼65 g) based on smartphone is able to detect nitrate concn. in water with a limit of detection of 0.2 ppm within 1 min. The nitrate ion detection on MoboSens platform is performed by a microfabricated microfluidic sensor utilizing cyclic voltammetry based electrochem. process. The stability of the measurements was verified by performing the expts. under varying temp., pH and ion interference conditions. The mobile phone app reports the quant. nitrate sensing results along with user's input metadata. The results can be automatically saved on secure cloud servers or can be pushed on public social media, e.g. Finally, the digital sensing information can be retrieved with geospatial information tagged on an internet map service, e.g. Bing Map for public sharing and viewing. We tested this lab-on-a-chip mobile sensing platform for field water quality measurement and confirmed our mobile sensing results with other existing anal. testing methods.
- 511Comina, G.; Suska, A.; Filippini, D. Autonomous Chemical Sensing Interface for Universal Cell Phone Readout Angew. Chem., Int. Ed. 2015, 54, 8708– 8712 DOI: 10.1002/anie.201503727Google ScholarThere is no corresponding record for this reference.
- 512Dalstein, O.; Ceratti, D. R.; Boissière, C.; Grosso, D.; Cattoni, A.; Faustini, M. Nanoimprinted, Submicrometric, MOF-Based 2D Photonic Structures: Toward Easy Selective Vapors Sensing by a Smartphone Camera Adv. Funct. Mater. 2016, 26, 81– 90 DOI: 10.1002/adfm.201503016Google Scholar512https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2MXhvFens7nN&md5=2a20a2a04e2e34efc4328066c5ca472fNanoimprinted, Submicrometric, MOF-Based 2D Photonic Structures: Toward Easy Selective Vapors Sensing by a Smartphone CameraDalstein, Olivier; Ceratti, Davide R.; Boissiere, Cedric; Grosso, David; Cattoni, Andrea; Faustini, MarcoAdvanced Functional Materials (2016), 26 (1), 81-90CODEN: AFMDC6; ISSN:1616-301X. (Wiley-VCH Verlag GmbH & Co. KGaA)A soft-lithog. approach to fabricate submicrometer metal org. framework (MOF)-based 2-dimensional photonic structures is described. Nanometric zeolitic imidazole framework material ZIF-8 (zinc) is chosen as the sensible MOF material because of its chem. stability and its vapor selective adsorption properties. Two different systems are fabricated: nanopatterned colloidal ZIF-8 homo- and ZIF-8/TiO2 heterostructures. Several features (stripes, squares, etc.) with dimensions of 200 nm are replicated on different substrates such as silicon, flexible plastics, and even aluminum cans, over relatively large surfaces (up to 1 cm2). The use of these photonic MOF-heterostructures as very low-cost sensing platforms compatible with smartphone technol. is demonstrated. This method relies on the evaluation of the change in diffraction efficiency of the photonic MOF-patterns, induced by the MOF refractive index variation, which is simply detected by a charge coupled device (CCD) camera, as those integrated in smartphones, without need for complex optical instrumentations for transduction data processing. Performances of the sensors are 1st evaluated using iso-Pr alc. adsorption/desorption cycling as a model case. A real environmental issue is tackled. Selective detection of styrene in presence of interfering water is demonstrated at concns. below the human permissible exposure limit. In situ ellispometric analyses are also carried out to confirm the sensor performances and to propose a mechanism for styrene uptake into the nanoMOFs.
- 513Li, F.; Bao, Y.; Wang, D.; Wang, W.; Niu, L. Smartphones for Sensing Sci. Bull. 2016, 61, 190– 201 DOI: 10.1007/s11434-015-0954-1Google ScholarThere is no corresponding record for this reference.
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ARTICLE SECTIONS
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- Abstract
- 1 Introduction
- 2 Diversity of Applications and Requirements for Modern Gas Sensors
- 3 State of the Art of Existing Sensing Concepts
- 4 General Principles of Multivariable Sensors
- 5 Multivariable Nonresonant and Resonant Impedance Sensors
- 6 Electromechanical Multivariable Resonant Sensors
- 7 Multivariable Field-Effect Transistor Sensors
- 8 Multivariable Photonic Resonant Sensors
- 9 Other Multivariable Sensor Technologies
- 10 Design Criteria for Multivariable Sensors
- 11 Benefits of Multivariable Sensors
- 12 Summary and Development Trends of Single-Output and Multivariable Sensors
- Author Information
- Biography
- Acknowledgment
- References
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