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Energy Harvesting Applications from Poly(ε-caprolactone) Electrospun Membranes
聚（ε-己内酯）静电纺丝膜的能量收集应用
- Vitor Sencadas* 维托·森卡达斯*Vitor Sencadas*Email: victors@uow.edu.au or vsencadas@gmail.comSchool of Mechanical, Materials, Mechatronic and Biomedical Engineering, University of Wollongong, Wollongong, New South Wales 2522, AustraliaARC Center of Excellence for Electromaterials Science, University of Wollongong, Wollongong, New South Wales 2522, AustraliaIllawarra Health and Medical Research Institute, University of Wollongong, Wollongong, New South Wales 2522, AustraliaMore by Vitor Sencadas
引用： ACS Appl. Polym.材料.2020， 2， 6， 2105–2110
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Abstract 抽象
Piezoelectricity is associated with crystalline materials that have noncentrosymmetric crystal units. This work reports the electroactive properties of poly(ε-caprolactone) (PCL) membranes produced by electrospinning. The individual PCL fiber shows an apparent piezoelectric constant of 5 ± 2 pm·V–1 with a longitudinal piezoelectric voltage coefficient of 0.25 Vm·N1–. Further, the PCL flexible electronic skin device exhibited superior mechano-sensitivity of 0.098 V·kPa–1, had the ability to measure small forces (1 mN), presents a remarkable output voltage stability (>16 000 cycles), and could accurately monitor human gait. The overall electroactive properties create opportunities in the development of environmentally friendly and low-cost energy nanoharvesting and wearable devices for human gait applications.
压电与具有非中心对称晶体单元的晶体材料有关。本工作报道了静电纺丝生产的聚（ε-己内酯）（PCL）膜的电活性。单个PCL光纤的表观压电常数为5 ± 2 pm·V –1 ，纵向压电电压系数为0.25 Vm·N 1– 。此外，PCL柔性电子皮肤器件具有0.098 V·kPa的优异机械灵敏度 –1 ，能够测量小力（1 mN），具有显著的输出电压稳定性（>16 000次循环），并能准确监测人体步态。整体电活性特性为开发用于人类步态应用的环保和低成本能源纳米采集和可穿戴设备创造了机会。
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Piezoelectricity and triboelectricity have been explored for the development of new sensors and energy scavenging and harvesting devices to recover energy from all sorts of vibrational sources such as ocean waves, (1) wind, (2) rain, (3) human motion, and heart beats. (4−6) All of these vibration sources contain a tremendous amount of mechanical energy that can be potentially transformed into electrical energy to power portable electronic devices.
压电和摩擦电已被探索用于开发新的传感器和能量清除和收集装置，以从各种振动源中回收能量，例如海浪，（1）风，（2）雨，（3）人体运动和心跳。（4−6） 所有这些振动源都含有大量的机械能，这些机械能有可能转化为电能，为便携式电子设备供电。
The fast advancement in micro- and nanotechnology is contributing to the development of new materials, architectures, and technological solutions to recover the vibrational mechanical energy into useful electrical power with minimal environmental impact and high noise reduction. (1,3) The intrinsic properties of piezoelectric materials, where a mechanical deformation results in a charge separation and an electrical output voltage is obtained, or vice versa, (7,8) make these materials ideal candidates for energy harvesting applications.
微纳米技术的快速发展正在促进新材料、架构和技术解决方案的发展，以将振动机械能回收为有用的电能，同时将环境影响降至最低，降噪效果高。（1,3） 压电材料的固有特性，其中机械变形导致电荷分离并获得电输出电压，反之亦然，（7,8） 使这些材料成为能量收集应用的理想候选者。
The piezoelectricity is a phenomenon found in polar crystals with a noncentrosymmetric crystallographic unit. Synthetic poly(vinylidene fluoride) (PVDF) and vinylidene fluoride (VDF) copolymers are widely explored for nanoharvesting applications (9) due to its electroactive response. However, PVDF and VDF copolymers are chemically stable, and their environmental degradation after usage takes several decades, leaving behind an important environmental footprint.
压电性是在极性晶体中发现的一种现象，具有非中心对称晶体学单元。合成聚偏氟乙烯 （PVDF） 和偏氟乙烯 （VDF） 共聚物因其电活性响应而被广泛探索用于纳米收获应用 （9）。然而，PVDF和VDF共聚物具有化学稳定性，使用后它们的环境降解需要几十年的时间，从而留下了重要的环境足迹。
With the advent of nanotechnology, many efforts are being made to create new materials with outstanding piezoelectric properties. However, some existing polymers could be piezoelectric, and this property is still to be reported and explored.
随着纳米技术的出现，人们正在努力创造具有出色压电性能的新材料。然而，一些现有的聚合物可能是压电的，这种特性仍有待报道和探索。
Poly(ε-caprolactone) (PCL) is a biocompatible and biodegradable polymer with applications as scaffolds for tissue engineering, (10) drug delivery devices, (11) and packing. (12) PCL is a semicrystalline polymer that crystallizes in an orthorhombic crystalline unit with a space group P212121, and the unit cell contains two chains in the opposite orientation (“up” and “down”). (13) Furthermore, the crystallinity degree of PCL can reach 70%, depending on the processing history. (14)
聚（ε-己内酯）（PCL）是一种生物相容性和可生物降解的聚合物，可用作组织工程、（10）药物输送装置、（11）和包装的支架。（12） PCL是一种半结晶聚合物，在空间群P2 1 2 1 2 1 的斜方晶单元中结晶，晶胞包含两条方向相反的链（“向上”和“向下”）。（13）此外，PCL的结晶度可以达到70%，这取决于加工历史。(14)
Electrospinning is a very versatile technique to manufacture fibers from organic macromolecules and polymer-based composites. Several parameters influence the diameter of the manufactured fibers, e.g. applied electric field, temperature, viscosity, and sample collection, just to mention a few. (15) During electrospinning, the high electric field that is applied to the polymer droplet mechanically draws the solvent and polymer chains inside of the jet, forcing the dipoles to align in the direction of the applied electric field. (15−17) Electrospinning is a promising technique to directly process electrically poled materials without the need of an extra electrical poling step, simplifying the material manufacture. (4,6,17)
静电纺丝是一种非常通用的技术，用于从有机大分子和聚合物基复合材料中制造纤维。有几个参数会影响所制造纤维的直径，例如施加的电场、温度、粘度和样品收集，仅举几例。（15） 在静电纺丝过程中，施加在聚合物液滴上的高电场机械地将溶剂和聚合物链吸引到射流内部，迫使偶极子沿施加电场的方向排列。（15−17） 静电纺丝是一种很有前途的技术，可以直接处理电极化材料，而无需额外的极化步骤，从而简化了材料制造。(4,6,17)
In this work, PCL was electrospun at room temperature and the fibers were collected on top of a static metallic plate. The sample presented a random distribution of smooth fibers, with an average diameter of 117 ± 17 nm (Figure 1a). The FTIR spectra of the PCL electrospun fiber mats present the characteristic stretching absorption band of the C–H between 2800–3000 cm–1. The carbonyl stretching (ν(C═O)) mode is easily detected at 1727 cm–1 (Figure 1b). Moreover, PCL presents an absorption band at 1293 and 1157 cm–1, assigned to C–O and C–C stretching in the crystalline and amorphous phase, (18,19) respectively.
在这项工作中，PCL在室温下静电纺丝，并将纤维收集在静态金属板的顶部。样品呈现出光滑纤维的随机分布，平均直径为117±17nm（图1a）。PCL静电纺丝纤维毡的FTIR光谱呈现出C-H在2800–3000 cm –1 之间的特征拉伸吸收带。羰基拉伸（ν（C═O））模式在1727厘米 –1 处很容易检测到（图1b）。此外，PCL 在 1293 和 1157 cm –1 处呈现吸收带，分别分配给结晶相和无定形相中的 C-O 和 C-C 拉伸 （18,19）。
Figure 1 图1
Figure 1. (a) Morphology of the PCL electrospun fiber mat, (b) FTIR spectroscopy recorded for the PCL membrane, (c) differential scanning calorimetry (DSC) behavior of the PCL electrospun membrane, and (d) WAXD patterns of solvent cast PCL film and electrospun membrane.
图 1.（a）PCL静电纺丝纤维毡的形态，（b）PCL膜的FTIR光谱记录，（c）PCL静电纺丝膜的差示扫描量热法（DSC）行为，以及（d）溶剂浇铸PCL薄膜和静电纺丝膜的蜡模。
It was observed that the melting transition of the PCL membrane presents a double shoulder with maxima at 63 °C (Figure 1c), suggesting a distribution of the size of the crystalline unit or the presence of fragmented crystallites. (20) This phenomenon is probably due to the fast solvent evaporation that occurs during electrospinning that prevents the polymer chains from reorganizing in a more stable fashion. Furthermore, the PCL membrane presented an overall crystallinity degree of 63% (see Figure S2).
观察到PCL膜的熔化转变在63°C时呈现出最大值的双肩（图1c），表明晶体单元大小的分布或碎片微晶的存在。（20）这种现象可能是由于静电纺丝过程中发生的快速溶剂蒸发，阻止了聚合物链以更稳定的方式重组。此外，PCL膜的整体结晶度为63%（见图S2）。
PCL film obtained from solvent casting from the same solution used to electrospun the fiber mats presented two strongest diffraction peaks with 2θ at 21.7° (100) and 24°, which results from the overlapping of the (200), (013), (112), and (104) crystalline planes. (13) Moreover, the diffraction peaks recorded for the electrospun membrane are broader and shifted to higher 2θ (Figure 1d), showing that the crystallites inside the polymeric electrospun fibers present residual microstrains, (21) and are in accordance with those observed in the thermal analysis (Figure 1c).
从用于静电纺丝纤维毡的相同溶液中通过溶剂浇铸获得的PCL薄膜在21.7°（100）和24°处呈现出两个最强的衍射峰，分别为2θ，这是由于（200）、（013）、（112）和（104）晶平面重叠的结果。（13）此外，静电纺丝膜记录的衍射峰更宽，并移向更高的2θ（图1d），表明聚合物静电纺丝纤维内部的微晶存在残留的微应变，（21）并且与热分析中观察到的一致（图1c）。
During electrospinning, the PCL crystallizes in a noncentrosymmetric orthorhombic crystalline unit cell with the potential to present electroactive properties. In this work, the nanoscale electroactive properties of the PCL nanofibers were investigated by depositing a single polymer fiber on top of a gold substrate. The atomic force microscopy (AFM) topography analysis shows a smooth PCL fiber (Figure 2a) with a 200 nm diameter and a height of 150 nm (Figure 2b).
在静电纺丝过程中，PCL在非中心对称的正交晶体晶胞中结晶，具有呈现电活性特性的潜力。在这项工作中，通过在金基板上沉积单根聚合物纤维来研究PCL纳米纤维的纳米级电活性性能。原子力显微镜（AFM）形貌分析显示了直径为200nm，高度为150nm的光滑PCL光纤（图2a）（图2b）。
Figure 2 图2
Figure 2. (a) AFM height image of the PCL electrospun fiber, (b) height profile of the PCL electrospun fiber, (c) PFM phase-voltage, and (d) amplitude–voltage hysteresis loop recorded for the PCL electrospun fiber.
图2.（a） PCL 静电纺丝光纤的 AFM 高度图像，（b） PCL 静电纺丝光纤的高度剖面，（c） PFM 相电压，以及 （d） PCL 静电纺丝光纤的幅压滞回线。
The investigation of the polarization switching features of the PCL fiber was investigated by the piezoresponse phase-voltage hysteresis loop (Figure 2c). The piezoforce microscopy (PFM) measurement showed that is possible to switch the C═O dipole by 180° at both polarities of the tip voltage (±5 V). Furthermore, the presence of butterfly shaped hysteresis loops recorded during the applied dc bias voltage suggests the presence of an electric field-induced strain amplitude behavior (Figure 2d).
通过压电响应相电压磁滞环路研究了PCL光纤的极化开关特性（图2c）。压力显微镜 （PFM） 测量表明，在尖端电压 （±5 V） 的两个极性下，可以将 C═O 偶极子切换 180°。此外，在施加直流偏置电压期间记录的蝶形磁滞回路的存在表明存在电场感应变幅度行为（图2d）。
At +5 V, the dipoles under the AFM conductive cantilever are parallel to the applied electric field. By changing the dc bias voltage polarity, the observed decrease in the amplitude suggests that the fiber started to contract. By decreasing the applied dc bias voltage down to −5 V, the dipoles underneath the AFM cantilever tip switch to the opposite direction (i.e., 180°phase change). At this point, the dipoles and electrical fields are parallel to each other. Therefore, the increase in the dc bias voltage leads to an increase in amplitude due to dipole expansion (Figure 2c and d). From the slope of the amplitude – dc bias voltage hysteresis loop, an apparent piezoelectric constant (di, j) of 5 ± 2 pm·V–1 was calculated.
在+5 V时，AFM导电悬臂下方的偶极子平行于施加的电场。通过改变直流偏置电压极性，观察到的幅度降低表明光纤开始收缩。通过将施加的直流偏置电压降低到−5 V，悬臂尖端下方的偶极子切换到相反的方向（即180°相变）。此时，偶极子和电场彼此平行。因此，由于偶极子膨胀，直流偏置电压的增加导致幅度增加（图2c和d）。从振幅-直流偏置电压磁滞回路的斜率来看，视压电常数（d i, j ）为5±2 pm·计算了 V –1 。
The obtained apparent longitudinal piezoelectric voltage coefficient (
, where ε0 and εr are the vacuum and sample permittivity (Figure S3), respectively) for the electrospun samples had a value of 0.25 Vm·N1–, which is higher than the values reported for lead zirconate titanate (PZT, g33 = 0.02 to 0.026 Vm·N1–) and barium titanate (BaTiO3, g33 = 0.013 Vm·N1–) (22) and is similar to the value reported for β-PVDF (g33 = 0.2787 Vm·N1–). (23)
得到的表观纵向压电电压系数（ 其中ε 0 和ε分别 r 是静电纺丝样品的真空度和样品介电常数（图S3），其值为0.25 Vm·N 1– ，高于锆钛酸铅（PZT，g 33 = 0.02至0.026 Vm·N 1– ）和钛酸钡（BaTiO，g 3 33 = 0.013 Vm·N 1– ） （22），与报告的 β-PVDF 值 （g 33 = 0.2787 Vm·N 1– ） 相似。(23)
The presence of an electroactive response by the PCL electrospun fiber is due to the crystalline orthorhombic unit with a space group P212121 (Figure 2d), which lacks a center of symmetry and is a necessary condition for the presence of piezoelectricity in a crystal. (24,25) The piezoelectric coefficient matrix for crystals with orthorhombic symmetry (P212121) is presented in the Supporting Information (Figure S4). Furthermore, the high electrical field used to process the polymer fibers leads to a dipolar preferential alignment normal to the longitudinal direction of the fiber axis, creating an electrical poled membrane with remarkable electroactive properties. (16,17) It was demonstrated in other polymer systems that the electrical field used during electrospinning was enough to produce and electrical poling of synthetic PVDF, (26) PLA, (17) or natural polymers like fish gelatin (4) and silk, (6) among other examples.
PCL静电纺丝纤维的电活性响应是由于具有空间群P2 1 2 1 2的晶体斜方单元 1 （图2d），该单元缺乏对称中心，是晶体中存在压电性的必要条件。（24,25）具有正交对称性的晶体的压电系数矩阵（ 1 1 P2,2,2 1 ）在支持信息（图S4）中给出。此外，用于加工聚合物纤维的高电场导致垂直于纤维轴纵向的偶极优先排列，从而产生具有显着电活性特性的电极膜。（16,17）在其他聚合物体系中证明，静电纺丝过程中使用的电场足以产生合成PVDF，（26）PLA，（17）或天然聚合物，如鱼明胶（4）和丝绸（6）等。
The energy scavenging of PCL electrospun membranes was assessed at macroscale by applying a dynamic oscillatory pressure to the electronic skin (e-skin) device (Figure 3a). The nanoharvester device showed a dependence of the output voltage with the increase of the frequency (Figure 3b). For the same applied mechanical stress, the output voltage increased with increasing the oscillatory load frequency, reaching a maximum output of 6 V for an applied frequency above 10 Hz, and the voltage output decreased to 4 V for frequencies above 20 Hz (Figure 3b). This behavior showed that at higher frequencies, the dipoles inside the polymer chains do not have enough time to recover to the relaxed state position before the next mechanical impact, reducing the dipolar movement amplitude and consequently the voltage output performance. An overall response time (τr) of 14 ms (Figure S5) was determined for the PCL e-skin device, which is in the same range of gelatin electrospun membranes. (4)
通过对电子皮肤（e-skin）设备施加动态振荡压力，在宏观尺度上评估了PCL静电纺丝膜的能量清除（图3a）。纳米收割器装置显示出输出电压随频率增加而产生的依赖性（图3b）。对于相同的施加机械应力，输出电压随着振荡负载频率的增加而增加，当施加频率高于10 Hz时，最大输出为6 V，而当频率高于20 Hz时，电压输出降低到4 V（图3b）。这种行为表明，在较高频率下，聚合物链内的偶极子没有足够的时间在下一次机械冲击之前恢复到松弛状态位置，从而降低了偶极运动幅度，从而降低了电压输出性能。PCL e-skin设备的总响应时间（τ r ）为14 ms（图S5），该设备位于明胶静电纺丝膜的相同范围内。(4)
Figure 3 图3
Figure 3. (a) Schematic of the mechanical setup for sample oscillatory stimulation. (b) Energy harvesting performance under different frequency conditions (applied force of 10 N). (c) Energy harvesting performance under different applied pressures (4 Hz). (d) Generated voltage and instantaneous power generated by the PCL electrospun harvester under an applied force of 10 N at a frequency of 4 Hz. (e) Calculation of the open-circuit voltage of the electrospun PCL energy harvester. (f) Stability and repeatability test of the energy harvester device under a 10 N force at a frequency of 16 Hz. (g) Walking monitoring. (h) Running monitoring. (i) Output voltage response with different external pressures.
图3.（a） 样品振荡刺激的机械装置示意图。（b） 不同频率条件下的能量收集性能（施加的力为10 N）。（c） 不同施加压力（4 Hz）下的能量收集性能。（d） PCL静电纺丝收割机在10 N的施加力下，频率为4 Hz的产生的电压和瞬时功率。 （e） 静电纺丝PCL能量收集器的开路电压的计算。（f） 能量收集器装置在16赫兹频率下在10 N力下的稳定性和重复性试验。 （g） 行走监测。（h） 运行监测。（i） 不同外部压力下的输出电压响应。
The energy harvesting device shows a linear relationship between the applied stress (Δσ) and the generated output voltage (ΔVoc) for an applied stress up to 63 kPa (Figure 3c). The nanoharvester sensitivity (
) of 0.098 V·kPa–1 is in the same range of other biological nanoharvester systems like silk fibroin (6) or synthetic PLA. (16)
能量收集装置显示了施加的应力（Δσ）和产生的输出电压（ΔV oc ）之间的线性关系，施加的应力高达63 kPa（图3c）。0.098 V·kPa –1 的纳米收获器灵敏度 （ ） 与其他生物纳米收获器系统（如丝素蛋白 （6） 或合成 PLA）处于同一范围。(16)
The generated electric power (
where A is the effective area of contact and V is the voltage generated by the energy harvesting device) was determined by placing loads of different resistances directly connected to the harvesting device (Figure 3d). A maximum instantaneous power density of 13 μW/cm2 at a 30 MΩ was achieved, as shown in Figure 3d. The instantaneous power generated by the PCL nanogenerator is similar to other energy harvesting devices manufactured by mixing a piezoceramic nanofiller with a polymer matrix. (27) However, it shows better performance when compared to PLA (16) (P = 0.07 μW/cm2), PVDF (P = 0.02 μW), or PVDF-TrFE (28) (P = 0.012 μW) polymers.
产生的电力（ 其中A是有效接触面积，V是能量收集装置产生的电压）是通过将不同电阻的负载直接连接到收集装置来确定的（图3d）。在30 MΩ下，最大瞬时功率密度为13 μW/cm 2 ，如图3d所示。PCL纳米发电机产生的瞬时功率类似于通过将压电陶瓷纳米填料与聚合物基质混合制造的其他能量收集装置。（27） 然而，与 PLA （16） （P = 0.07 μW/cm 2 ）、PVDF （P = 0.02 μW） 或 PVDF-TrFE （28） （P = 0.012 μW） 聚合物相比，它显示出更好的性能。
The PCL energy harvester, as a power source, follows the linear circuit theory (29) with a theoretical output voltage of 11.5 V (Figure 3e, see Supporting Information). Further, the stability and repeatability of the e-skin device were assessed by applying a force of 10 N with a frequency of 16 Hz (Figure 3f) over an extended cycling time (16 000 cycles). The amplitude of the output voltage exhibits negligible variations, and the overall performance of the developed PCL energy harvester showed remarkable stability and repeatability, without noticeable electrical degradation, even after being stored at room conditions for one month (Figure S5).
PCL能量收集器作为电源，遵循线性电路理论（29），理论输出电压为11.5 V（图3e，参见支持信息）。此外，通过在延长的循环时间（16 000次循环）内施加频率为10 N的力（图3f），评估了e-skin设备的稳定性和可重复性。输出电压的幅度变化可以忽略不计，开发的PCL能量收集器的整体性能显示出显着的稳定性和可重复性，即使在室温下储存一个月后也没有明显的电气退化（图S5）。
The energy efficiency η of the nanoharvester can be determined by the ratio between electrical energy output (Eout) and the mechanical energy input (Ein) during the oscillatory mechanical pressure (see Supporting Information). The PCL nanoharvester showed an efficiency of energy conversion of 10% (see Supporting Information). In the literature, a broad range of efficiency values are reported; however, one should acknowledge that the calculation of the individual fiber strain under the applied oscillatory mechanical pressure is difficult to determine with accuracy, and this is one of the reasons for the discrepancies found in the literature.
纳米收割机的能效η可以通过振荡机械压力期间电能输出（E out ）和机械能输入（E in ）之间的比率来确定（见支持信息）。PCL纳米收割机的能量转换效率为10%（见支持信息）。在文献中，报告了广泛的效率值;然而，人们应该承认，在施加的振荡机械压力下计算单个纤维应变很难准确确定，这也是文献中发现差异的原因之一。
To demonstrate the sensing and energy harvesting capabilities of the PCL fiber membranes, the device was placed on top of an insole of a sports shoe, and the biomechanical energy generated during walking (Figure 3g) and running (Figure 3h) was recorded. The output voltage generated by the energy harvester followed the imparted mechanical pressure applied during the different sport activities, which demonstrates that these devices can be used to accurately monitor the human gait but also generate valuable electrical energy that could be used to drive portable electronic gadgets. Furthermore, when small weights (100 and 400 mg) were dropped from a height of 50 mm on top of the e-skin, a clear output voltage was observed from the device (Figure 3h–i). This result shows that the e-skin has promising pressure sensing features, covering the low detection range of metallic strain gauges. (30,31)
为了演示PCL纤维膜的传感和能量收集能力，将该装置放置在运动鞋的鞋垫顶部，并记录了步行（图3g）和跑步（图3h）期间产生的生物力学能量。能量收集器产生的输出电压跟随在不同体育活动中施加的机械压力，这表明这些设备可用于准确监测人体步态，但也会产生宝贵的电能，可用于驱动便携式电子产品。此外，当小砝码（100 和 400 mg）从 50 mm 的高度掉落到电子皮肤顶部时，从设备观察到清晰的输出电压（图 3h-i）。结果表明，e-skin具有很有前途的压力传感功能，覆盖了金属应变片的低检测范围。(30,31)
In summary, this work reports the presence of electroactivity in the PCL that is due to its semicrystalline nature, especially the orthorhombic crystalline unit with a space group P212121. The unique combination of a fast-drying polymer solution under a high electric field during electrospinning promotes the preferential alignment of the polymer chains in the longitudinal direction of the electrospun fiber, and the orientation of the C═O dipoles along the polymer chain lead to a permanent dipolar moment.
总之，这项工作报告了由于其半结晶性质而导致的PCL中存在电活性，特别是具有空间群P2 1 2 1 2的斜方晶体单元 1 。静电纺丝过程中高电场下快干聚合物溶液的独特组合促进了聚合物链在静电纺丝纤维纵向上的优先排列，并且C═O偶极子沿聚合物链的取向导致永久偶极矩。
The PCL electroactive properties and remarkable sensing performance open new opportunities in the development of environmentally friendly and low-cost energy harvester devices, in vitro and in vivo diagnostics and early detection of health conditions, epidermal electronic devices, artificial skins, and intelligent systems for soft robotics.
PCL的电活性特性和卓越的传感性能为开发环保和低成本的能量收集器设备、体外和体内诊断以及健康状况的早期检测、表皮电子设备、人造皮肤和软机器人智能系统开辟了新的机会。
Supporting Information 支持信息
The Supporting Information is available free of charge at https://pubs.acs.org/doi/10.1021/acsapm.0c00209.
支持信息可在 https://pubs.acs.org/doi/10.1021/acsapm.0c00209 免费获得。
Figure S1, mechanical behavior recorded for the PCL fiber mat; Figure S2, DSC thermogram for the solvent casted PCL film; Figure S3, dielectric permittivity of PCL electrospun membrane; Figure S4, piezoelectric matrix for the orthorhombic crystal unit (point group 212121); Figure S5, (a) electrical output voltage recorded for the empty PDMS cage, (b) forward and reverse electrical output voltage for the PCL as-spun mat, (c) response time recorded for the PCL nanoharvester, and (d) electrical output voltage collected for the PCL nanoharvester after stored for one month at room conditions; Figure S6, (a) measure the output voltage at an external load of 30 MΩ, (b) the square of the output voltage for integration to obtain the instantaneous electric power output, and (c) the integration part of the time-dependent output voltage (PDF)
图S1，PCL纤维毡的机械性能记录;图S2，溶剂浇注PCL薄膜的DSC热图;图S3，PCL静电纺丝膜的介电常数;图S4，正交晶体单元的压电矩阵（点组 1 1 1 2,2,2）;图S5，（a）记录的空PDMS笼的电输出电压，（b）PCL纺丝垫的正向和反向电输出电压，（c）PCL纳米收割机的响应时间记录，以及（d）在室温下储存一个月后为PCL纳米收割机收集的电输出电压;图S6，（a）测量30MΩ外部负载下的输出电压，（b）输出电压的平方，用于积分以获得瞬时电功率输出，以及（c）瞬态输出电压的积分部分（PDF）Movie S1: PCL nanoharvester performance (MP4)
电影 S1：PCL 纳米收割机性能 （ MP4）
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Author Information 作者信息
- Vitor Sencadas - School of Mechanical, Materials, Mechatronic and Biomedical Engineering, University of Wollongong, Wollongong, New South Wales 2522, Australia; ARC Center of Excellence for Electromaterials Science, University of Wollongong, Wollongong, New South Wales 2522, Australia; Illawarra Health and Medical Research Institute, University of Wollongong, Wollongong, New South Wales 2522, Australia;
http://orcid.org/0000-0003-1986-1348;
Vitor Sencadas - 卧龙岗大学机械、材料、机电一体化和生物医学工程学院，澳大利亚新南威尔士州卧龙岗 2522;ARC电材料科学卓越中心，卧龙岗大学，卧龙岗，新南威尔士州，2522，澳大利亚;伊拉瓦拉健康与医学研究所，卧龙岗大学，卧龙岗，新南威尔士州，2522，澳大利亚; http://orcid.org/0000-0003-1986-1348;电子邮件： victors@uow.edu.auvsencadas@gmail.com
Acknowledgments 确认
The author acknowledges the University of Wollongong for the Major Equipment Grant 2018.
作者感谢卧龙岗大学提供 2018 年主要设备补助金。
References 引用
This article references 31 other publications.
本文参考了其他 31 篇出版物。
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1Kim， H.-M.用于海洋动能收集的电活性聚合物：文献综述和研究需求。海洋工程与海洋能源学报 2018， 4 （4）， 343– 365， DOI： 10.1007/s40722-018-0121-2 - 2Feng, Y.; Zhang, L.; Zheng, Y.; Wang, D.; Zhou, F.; Liu, W. Leaves based triboelectric nanogenerator (TENG) and TENG tree for wind energy harvesting. Nano Energy 2019, 55, 260– 268, DOI: 10.1016/j.nanoen.2018.10.075Google Scholar Google 学术搜索2https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC1cXitFKmurrL&md5=9621d391f307b21b253c934bd6326839Leaves based triboelectric nanogenerator (TENG) and TENG tree for wind energy harvestingFeng, Yange; Zhang, Liqiang; Zheng, Youbin; Wang, Daoai; Zhou, Feng; Liu, WeiminNano Energy (2019), 55 (), 260-268CODEN: NEANCA; ISSN:2211-2855. (Elsevier Ltd.)Triboelec. nanogenerators based on biodegradable plant leaf and leaf powder is fabricated through a simple and cost effective method. The short-circuit current (Isc) and output voltage (Vo) of fresh leaf can reach 15 μA and 430 V. Dry leaf is grinded into powder to make solve problem of frangibility when contact and make full use of the leaf. Poly-L-Lysine is used to modify leaf powder and enhance the output performance of leaf powder based TENG. After surface modification, the Isc and Vo can reach high as 60 μA and 1000 V, resp., which can easily power a com. elec. watch and 868 LEDs. To extend the drive mode, wind driven TENG (WTENG) based on PLL modified leaf powder is designed for harvesting wind energy and the max. Isc can reach 150 μA under 7 m/s wind speed. The WTENG is designed to power an "EXIT" LED light for exit passageway in windy weather. Furthermore, TENG tree is designed basing on the live leaves and artificial leaves, which have promising potential use in the remote regions, such as in the mountains or islands, for early warning and indicator light.
2冯，Y.;张，L.;郑彦;王，D.;周，F.;Liu， W.Leaves 基摩擦电纳米发电机 （TENG） 和 TENG 树用于风能收集.纳米能源 2019， 55， 260– 268， DOI： 10.1016/j.nanoen.2018.10.075 - 3Mariello, M.; Guido, F.; Mastronardi, V. M.; Todaro, M. T.; Desmaële, D.; De Vittorio, M. Nanogenerators for harvesting mechanical energy conveyed by liquids. Nano Energy 2019, 57, 141– 156, DOI: 10.1016/j.nanoen.2018.12.027Google Scholar Google 学术搜索3https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC1cXisFynsrbN&md5=f5bf689513cdcfde1afde2c8161f5150Nanogenerators for harvesting mechanical energy conveyed by liquidsMariello, M.; Guido, F.; Mastronardi, V. M.; Todaro, M. T.; Desmaele, D.; De Vittorio, M.Nano Energy (2019), 57 (), 141-156CODEN: NEANCA; ISSN:2211-2855. (Elsevier Ltd.)A review. The huge mech. energy available in the environment, mostly in form of kinetic energy of fluids such as wind, ocean and river currents or waves, is currently harvested by cumbersome, low efficiency and high environmental impact technologies. New approaches are needed for producing more compact and distributed mech. energy converters. Nanogenerators and related micro and nanotechnologies can help in developing new environmentally friendly and biocompatible technologies. To face this challenge, new conversion phys. principle, device structures and system architectures are currently being studied and developed. This work reviews the most recent advances on nanogenerators for harvesting energy transported by liqs. in the environment such as water motion in rivers and marine environments and kinetic energy in rain. It discusses the most common phys. transduction mechanisms, with a focus on piezoelec. and triboelec. nanogenerators (PENG/TENG), the requirements for producing flexible devices for effective conversion and the system architectures for optimizing the fluid-device interaction for producing large and fast oscillations, such as flapping, fluttering or galloping, from quasi-static or quasi-laminar fluid motion. Addnl., the work encompasses challenges such as waterproofing and antibiofouling, important issues in sub-marine and underwater environment.
3玛丽埃洛，M.;圭多，F.;马斯特罗纳迪，V.M.;托达罗，MT;德斯梅尔，D.;De Vittorio， M.用于收集液体输送的机械能的纳米发电机。纳米能源 2019， 57， 141– 156， DOI： 10.1016/j.nanoen.2018.12.027 - 4Ghosh, S. K.; Adhikary, P.; Jana, S.; Biswas, A.; Sencadas, V.; Gupta, S. D.; Tudu, B.; Mandal, D. Electrospun gelatin nanofiber based self-powered bio-e-skin for health care monitoring. Nano Energy 2017, 36, 166– 175, DOI: 10.1016/j.nanoen.2017.04.028Google Scholar Google 学术搜索4https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2sXms1Wmsbc%253D&md5=dbed650bf0563db7d30fe98613bed844Electrospun gelatin nanofiber based self-powered bio-e-skin for health care monitoringGhosh, Sujoy Kumar; Adhikary, Prakriti; Jana, Santanu; Biswas, Anirban; Sencadas, Vitor; Gupta, Sudipto Dutta; Tudu, Bipan; Mandal, DipankarNano Energy (2017), 36 (), 166-175CODEN: NEANCA; ISSN:2211-2855. (Elsevier Ltd.)Progress on smart self-powered electronic skin (e-skin) presents unique opportunities to detect and discriminate static human physiol. signals and dynamic tactile stimuli. Nevertheless, development of piezoelec. materials possessing adequate flexibility, light wt., ease of large-area processing, low cost and environmental safety are attractive but remains a challenging choice for next-generation pressure/force sensors and mech. energy harvesters. Here, we design a wearable bio-inspired piezoelec. pressure sensor (i.e., bio-e-skin) from structurally stable fish gelatin nanofibers (GNFs) using large area compatible electrospining technol. Owing to superior mechanosensitivity (∼0.8 V kPa-1), the bio-e-skin can mimic spatiotemporal human perception and monitors real-time human physiol. signals in non-invasive rational strategy. More importantly, nanoscale ferro- and piezo-electricity (d33∼-20 pm/V) in GNFs, realized by piezoresponse force microscopy allow the bio-e-skin to be self-powered with excellent operational stability (over 108,000 cycles) and anti-fatigue (over 6 mo) properties which solve the complication of external power supply for pressure sensing applications.
4戈什，SK;阿迪卡里，P.;贾娜，S.;比斯瓦斯，A.;森卡达斯，V.;古普塔，S.D.;图杜，B.;Mandal， D.基于静电纺丝明胶纳米纤维的自供电生物电子皮肤，用于医疗保健监测。纳米能源 2017， 36， 166– 175， DOI： 10.1016/j.nanoen.2017.04.028 - 5Guerin, S.; Tofail, S. A. M.; Thompson, D. Longitudinal Piezoelectricity in Orthorhombic Amino Acid Crystal Films. Cryst. Growth Des. 2018, 18 (9), 4844– 4848, DOI: 10.1021/acs.cgd.8b00835Google Scholar5https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC1cXhsVWitLnE&md5=4955a76f454c6e8d8d8f0c76c1ab07cdLongitudinal Piezoelectricity in Orthorhombic Amino Acid Crystal FilmsGuerin, Sarah; Tofail, Syed A. M.; Thompson, DamienCrystal Growth & Design (2018), 18 (9), 4844-4848CODEN: CGDEFU; ISSN:1528-7483. (American Chemical Society)The symmetry of orthorhombic amino acid single crystals precludes the existence of a longitudinal piezoelec. response. Here the authors report the growth of amino acid crystal films on conductive substrates that demonstrate measurable longitudinal piezoelectricity of the same order of magnitude as large piezoelec. biopolymers. Crystal films of the nonproteinogenic amino acid hydroxyproline show a response of the same magnitude as quartz single crystals. This response is deconstructed using d. functional theory single crystal predictions and cross-sectional electron microscopy. These results verify that amino acid films can serve as simple piezoelec. transducers, which could be used for a variety of energy harvesting applications.
5盖林，S.;托法尔，S.A.M.;Thompson， D.斜方氨基酸晶体薄膜中的纵向压电性。Cryst. 增长 Des. 2018， 18 （9）， 4844– 4848， DOI： 10.1021/acs.cgd.8b00835 - 6Sencadas, V.; Garvey, C.; Mudie, S.; Kirkensgaard, J. J. K.; Gouadec, G.; Hauser, S. Electroactive properties of electrospun silk fibroin for energy harvesting applications. Nano Energy 2019, 66, 104106, DOI: 10.1016/j.nanoen.2019.104106Google Scholar6https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC1MXhvVKktbnK&md5=b1f2f912da94aa27339a9500fe9ef914Electroactive properties of electrospun silk fibroin for energy harvesting applicationsSencadas, Vitor; Garvey, Christopher; Mudie, Stephen; Kirkensgaard, Jacob J. K.; Gouadec, Gwenael; Hauser, SamuelNano Energy (2019), 66 (), 104106CODEN: NEANCA; ISSN:2211-2855. (Elsevier Ltd.)Silk fibroin (SF) is a sustainable material explored with success in the textile and biomedical industries. This protein has outstanding mech. and elec. properties that could be used for advanced technol. applications. In this work, silk fibroin fibrous membranes were processed by electrospinning, with conditions obtained through orthogonal exptl. design. Due to their high-water affinity, the membranes were stabilized against aq. environments by exposure to methanol (MeOH) in vapor phase. Individual SF fibers present an apparent piezoelec. const. (d33) of 38 ± 2 pm/V for the as-spun ones and 28 ± 3 pm/V for those submitted to MeOH in vapor phase, a piezoelec. voltage coeff. (g33) of 1.05 and 0.53 Vm. N-1, resp., a mechano-sensibility of 0.15 V kPa-1, an energy storage capacity of 85 μJ, and an efficiency up to 21%. When the SF is submitted to MeOH in vapor phase, no effect was obsd. in the protein secondary structures. This work represents a new insight into the origin of the piezoelec. properties of SF and opens new opportunities for applications in microelectronics engineering for self-powered epidermal electronics, implantable medical devices, and personalized health care systems.
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- 10Dwivedi, R.; Kumar, S.; Pandey, R.; Mahajan, A.; Nandana, D.; Katti, D. S.; Mehrotra, D. Polycaprolactone as biomaterial for bone scaffolds: Review of literature. Journal of Oral Biology and Craniofacial Research 2020, 10, 381, DOI: 10.1016/j.jobcr.2019.10.003Google Scholar10https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A280%3ADC%252BB3MfhvV2ksw%253D%253D&md5=0f248ff87af9772048a2785c481213fbPolycaprolactone as biomaterial for bone scaffolds: Review of literatureDwivedi Ruby; Nandana Deepti; Mehrotra Divya; Kumar Sumit; Pandey Rahul; Mahajan Aman; Katti Dhirendra SJournal of oral biology and craniofacial research (2020), 10 (1), 381-388 ISSN:2212-4268.Bone tissue engineering using polymer based scaffolds have been studied a lot in last decades. Considering the qualities of all the polymers desired to be used as scaffolds, Polycaprolactone (PCL) polyester apart from being biocompatible and biodegradable qualifies to an appreciable level due its easy availability, cost efficacy and suitability for modification. Its adjustable physio-chemical state, biological properties and mechanical strength renders it to withstand physical, chemical and mechanical, insults without significant loss of its properties. This review aims to critically analyse the efficacy of PCL as a biomaterial for bone scaffolds.
- 11Chang, S. H.; Lee, H. J.; Park, S.; Kim, Y.; Jeong, B. Fast Degradable Polycaprolactone for Drug Delivery. Biomacromolecules 2018, 19 (6), 2302– 2307, DOI: 10.1021/acs.biomac.8b00266Google Scholar11https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC1cXptV2msbw%253D&md5=de2c35a57e6905b01d004ea032c8bd65Fast Degradable Polycaprolactone for Drug DeliveryChang, Seo Hee; Lee, Hyun Jung; Park, Sohee; Kim, Yelin; Jeong, ByeongmoonBiomacromolecules (2018), 19 (6), 2302-2307CODEN: BOMAF6; ISSN:1525-7797. (American Chemical Society)Polycaprolactone (PCL) was reported a long time ago; however, its biomedical applications has not been extensively investigated in comparison with poly(lactide-co-glycolide) (PLGA) due to its too slow degrdn. profile. Here, we are reporting an oxalate-connected oligocaprolactone multiblock copolymer (PCL-OX) as a fast degradable PCL while maintaining its cryst. properties and low m.p. of PCL. The in vivo application of the paclitaxel-loaded PCL-OX microspheres provided a steady plasma drug concn. of 6-9 μg/mL over 28 days, similar to that of the PLGA microspheres. Both PCL and PLGA microspheres were completely cleared two months after in vivo implantation. The PCL-OX microspheres showed a similar tissue compatibility to that of PLGA microspheres in the s.c. layer of rats. These findings suggest that PCL-OX is a useful biomaterial that solves the slow degrdn. problems of PCL and, thus, may find uses in other biomedical applications as an alternative to PLGA.
- 12Cesur, S.; Köroğlu, C.; Yalçın, H. T. Antimicrobial and biodegradable food packaging applications of polycaprolactone/organo nanoclay/chitosan polymeric composite films. J. Vinyl Addit. Technol. 2018, 24 (4), 376– 387, DOI: 10.1002/vnl.21607Google Scholar12https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2sXhsV2itL7K&md5=30d0f5dfceec7303c6b10203d1f6349cAntimicrobial and biodegradable food packaging applications of polycaprolactone/organo nanoclay/chitosan polymeric composite filmsCesur, Serap; Koeroglu, Cansu; Yalcin, Huesniye TanselJournal of Vinyl and Additive Technology (2018), 24 (4), 376-387CODEN: JVATF4; ISSN:1083-5601. (John Wiley & Sons, Inc.)Biodegradable and antimicrobial polymeric food packaging materials are very important because of environmental problems, for quality, and the shelf life of the product. The aim of this paper is to produce antimicrobial and biodegradable food packaging films with polycaprolactone (PCL). Using the amt. of PCL (wt./wt.) as the basis and to control the degrdn. time and to give antimicrobial properties, 0.4 wt% of organo nano clay (C) and 25, 50, and 75 wt% chitosan (K), and the use of glycerol monooleate (GMO) or oleic acid (OA) as a plastifier (5, 10, 20, and 30 wt%) are added and 12 polymeric composite films were prepd. The samples were coded as PCL (P), organo nanoclay (C), oleic acid (O), and glycerol monooleate (G). For example, P_C0.4_G5 refers to the PCL composite film contg. 0.4 wt% clay and 5 wt% glycerol monooleate (G). The disk diffusion procedure with Escherichia coli, Pseudomonas aeruginosa, Bacillus cereus, and Candida albicans test microorganisms were used to evaluate the antimicrobial properties of the films. PCL_C0.4_O5, PCL_C0.4_G5, PCL_C0.4_G10_K25, PCL_C0.4_O10_K25, and PCL_C0.4_O20_K50 and neat chitosan films have antimicrobial properties. A small amt. of organo nano clay, 0.4 wt%, has an antimicrobial effect on C. albicans. The PCL_C0.4_G10_K25 composite film has an antimicrobial effect on E. coli, P. aeruginosa, and C. albicans. Mech. tests were performed, and it was obsd. that the mech. properties of PCL composite films decrease with the addn. of chitosan. J. VINYL ADDIT. TECHNOL., 2017. © 2017 Society of Plastics Engineers.
- 13Bittiger, H.; Marchessault, R. H.; Niegisch, W. D. Crystal structure of poly-[epsilon]-caprolactone. Acta Crystallogr., Sect. B: Struct. Crystallogr. Cryst. Chem. 1970, 26 (12), 1923– 1927, DOI: 10.1107/S0567740870005198Google Scholar13https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADyaE3MXks1Oiug%253D%253D&md5=977eb5f8ea713d68e8de1e559ef7825fCrystal structure of poly-ε-caprolactoneBittiger, H.; Marchessault, R. H.; Niegisch, W. D.Acta Crystallographica, Section B: Structural Crystallography and Crystal Chemistry (1970), 26 (12), 1923-7CODEN: ACBCAR; ISSN:0567-7408.The unit cell of poly-ε-caprolactone is orthorhombic with dimensions a = 7.496 ± 0.002, b = 4.974 ± 0.001, c = 17.297 ± 0.023 Å (fiber axis). The space group is P212121. This unit cell is only compatible with an extended planar chain conformation of the mol. involving 2 monomer residues related by a twofold screw axis in the chain direction. The P212121 space group and the d. of 1.146 indicate that the unit cell contains 2 chains with opposite orientation ("up" and "down"). Intensity measurements and structure factor calcns. require the rotation of the plane of the chains about their axis to an angle of 28° with respect to the a axis; longitudinal chain shift places the ester groups in planes perpendicular to the c axis. Folded chain single crystals with a lancet-like structure were obsd. by electron microscopy.
- 14Labet, M.; Thielemans, W. Synthesis of polycaprolactone: a review. Chem. Soc. Rev. 2009, 38 (12), 3484– 3504, DOI: 10.1039/b820162pGoogle Scholar14https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD1MXhsVanurrJ&md5=37be671578dc2e20e673df08d3e454cbSynthesis of polycaprolactone: a reviewLabet, Marianne; Thielemans, WimChemical Society Reviews (2009), 38 (12), 3484-3504CODEN: CSRVBR; ISSN:0306-0012. (Royal Society of Chemistry)A review. Polycaprolactone (PCL) is an important polymer due to its mech. properties, miscibility with a large range of other polymers and biodegradability. Two main pathways to produce polycaprolactone have been described in the literature: the polycondensation of a hydroxycarboxylic acid: 6-hydroxyhexanoic acid, and the ring-opening polymn. (ROP) of a lactone: ε-caprolactone (ε-CL). This crit. review summarises the different conditions which have been described to synthesize PCL, and gives a broad overview of the different catalytic systems that were used (enzymic, org. and metal catalyst systems). A surprising variety of catalytic systems have been studied, touching on virtually every section of the periodic table. A detailed list of reaction conditions and catalysts/initiators is given and reaction mechanisms are presented where known. Emphasis is put on the ROP pathway due to its prevalence in the literature and the superior polymer that is obtained. In addn., ineffective systems that have been tried to catalyze the prodn. of PCL are included in the electronic supplementary information for completeness (141 refs.).
- 15Seeram, R.; Teik-cheng, L.; Kazutoshi, F. An Introduction To Electrospinning and Nanofibers; World Scientific Publishing Company: 2005.Google ScholarThere is no corresponding record for this reference.
- 16Sultana, A.; Ghosh, S. K.; Sencadas, V.; Zheng, T.; Higgins, M. J.; Middya, T. R.; Mandal, D. Human skin interactive self-powered wearable piezoelectric bio-e-skin by electrospun poly-l-lactic acid nanofibers for non-invasive physiological signal monitoring. J. Mater. Chem. B 2017, 5 (35), 7352– 7359, DOI: 10.1039/C7TB01439BGoogle Scholar16https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2sXht1yrt7jL&md5=682d0662be3df792f6c356d2bd304abbHuman skin interactive self-powered wearable piezoelectric bio-e-skin by electrospun poly-L-lactic acid nanofibers for non-invasive physiological signal monitoringSultana, Ayesha; Ghosh, Sujoy Kumar; Sencadas, Vitor; Zheng, Tian; Higgins, Michael J.; Middya, Tapas Ranjan; Mandal, DipankarJournal of Materials Chemistry B: Materials for Biology and Medicine (2017), 5 (35), 7352-7359CODEN: JMCBDV; ISSN:2050-7518. (Royal Society of Chemistry)Flexible and wearable piezoelec. bio e-skin (PBio-e-skin) based on electrospun poly(L-lactic acid) PLLA nanofiber membrane is demonstrated for non-invasive human physiol. signal monitoring and detecting dynamic tactile stimuli. The mol. orientations of the C=O dipoles by electrospinning technique result in a longitudinal piezoelec. charge co-efficient (d33) value of ∼(3 ± 1) pm V-1 realized by piezoresponse force microscopy, allowing the PBio-e-skin for pressure sensing applications. The robust mech. strength (Young's modulus ∼50 MPa) of nanofiber membrane ensures PBio-e-skin's superior operational stability over 375 000 cycles. Owing to the superior mechanosensitivity of ∼22 V N-1, PBio-e-skin has the ability to measure subtle movement of muscle in the internal organs such as esophagus, trachea, motion of joints and arterial pressure by recognition of strains on human skin. This flexible and light wt. PBio-e-skin precisely detects vital signs and provides important clin. insights without using any external power source. Eventually, the low cost, environmental friendly PBio-e-skin will have a huge impact in a broad range of applications including self-powered wearable health care systems, human-machine interfacing devices, artificial intelligence and prosthetic skin.
- 17Sencadas, V.; Ribeiro, C.; Heredia, A.; Bdikin, I. K.; Kholkin, A. L.; Lanceros-Mendez, S. Local piezoelectric activity of single poly(L-lactic acid) (PLLA) microfibers. Appl. Phys. A: Mater. Sci. Process. 2012, 109 (1), 51– 55, DOI: 10.1007/s00339-012-7095-zGoogle Scholar17https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC38Xhtl2qsb3M&md5=e82ed72af70e600afbf08b693e68b52aLocal piezoelectric activity of single poly(L-lactic acid) (PLLA) microfibersSencadas, V.; Ribeiro, C.; Heredia, A.; Bdikin, I. K.; Kholkin, A. L.; Lanceros-Mendez, S.Applied Physics A: Materials Science & Processing (2012), 109 (1), 51-55CODEN: APAMFC; ISSN:0947-8396. (Springer)Local piezoelec. properties of the poly(L-lactic acid) individual electrospun fibers were studied by Piezoresponse Force Microscopy. Piezoelec. response, polarization switching, and nanoscale patterning of the fibers were demonstrated in this important biomaterial, thus opening interesting possibilities for tissue engineering and sensing/actuating applications.
- 18Elzein, T.; Nasser-Eddine, M.; Delaite, C.; Bistac, S.; Dumas, P. FTIR study of polycaprolactone chain organization at interfaces. J. Colloid Interface Sci. 2004, 273 (2), 381– 387, DOI: 10.1016/j.jcis.2004.02.001Google Scholar18https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD2cXivFGns7c%253D&md5=8a089df4f0732146b5987314cbef4ccfFTIR study of polycaprolactone chain organization at interfacesElzein, Tamara; Nasser-Eddine, Mohamad; Delaite, Christelle; Bistac, Sophie; Dumas, PhilippeJournal of Colloid and Interface Science (2004), 273 (2), 381-387CODEN: JCISA5; ISSN:0021-9797. (Elsevier Science)Polycaprolactone (PCL), extensively known as a biomaterial, is the subject of this paper. Knowing well that some biomaterial applications exhibit specific chain organization, we focused our study on the orientation of PCL chains when this polymer is adsorbed (spin-coated) on inert substrates such as gold-coated glass slides. The main technique allowing adsorbed thin films anal. that we chose is polarization-modulation IR reflection-absorption spectroscopy (PM-IRRAS), which permits qual. and quant. detn. of chain anisotropy in the confined layers at the interface. Based on our spectroscopic results, we achieved an adsorption model of PCL chains and we calcd. orientation angles with respect to the substrate normal. Calcd. values show a quasi-perpendicular deposition of PCL chains on the gold substrate. Moreover, PCL thin films remain highly cryst., a fact which could be the basis of the important anisotropy of PCL chains.
- 19Kossack, W.; Seidlitz, A.; Thurn-Albrecht, T.; Kremer, F. Molecular Order in Cold Drawn, Strain-Recrystallized Poly(ε-caprolactone). Macromolecules 2017, 50 (3), 1056– 1065, DOI: 10.1021/acs.macromol.6b02714Google Scholar19https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2sXhvFeqsL4%253D&md5=aa755f31723bb79b71f08501931666ebMolecular Order in Cold Drawn, Strain-Recrystallized Poly(ε-caprolactone)Kossack, Wilhelm; Seidlitz, Anne; Thurn-Albrecht, Thomas; Kremer, FriedrichMacromolecules (Washington, DC, United States) (2017), 50 (3), 1056-1065CODEN: MAMOBX; ISSN:0024-9297. (American Chemical Society)Biaxial order in free-standing films of Poly-ε-caprolactone (PCL), induced by plastic deformation and fibrillation, is studied by IR transition moment orientational anal. (IR-TMOA) and x-ray diffraction (pole figures). This enables one to det. the order parameter tensor for the different mol. moieties with respect to the sample coordinate system. The main chains of the polymers are aligned with the stretching direction (x), leading to a strong order of the crystallites (Hermans orientation function, Sxx= 0.9 ± 0.1), and less ordered, amorphous regions (Sxx= 0.34 ± 0.1). The microscopic biaxiality of the system, |Syy-Szz| ≈ 0.1, is caused by the macroscopically asym. deformation perpendicular to the stretching direction. Cold-drawing leads to a redn. in crystallinity and distorted crystallites in the fibrils, indicating the absence of 'melting and recrystn.' or "fine slip" processes.
- 20Sencadas, V.; Costa, C. M.; Botelho, G.; Caparrós, C.; Ribeiro, C.; Gómez-Ribelles, J. L.; Lanceros-Mendez, S. Thermal Properties of Electrospun Poly(Lactic Acid) Membranes. J. Macromol. Sci., Part B: Phys. 2012, 51 (3), 411– 424, DOI: 10.1080/00222348.2011.597325Google Scholar20https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC38XktVagsrg%253D&md5=05d6d8c3d3551cbdd7fa5058203d159aThermal Properties of Electrospun Poly(Lactic Acid) MembranesSencadas, V.; Costa, C. M.; Botelho, G.; Caparros, C.; Ribeiro, C.; Gomez-Ribelles, J. L.; Lanceros-Mendez, S.Journal of Macromolecular Science, Part B: Physics (2012), 51 (3), 411-424CODEN: JMAPBR; ISSN:0022-2348. (Taylor & Francis, Inc.)Poly(lactic acid) (PLA) electrospun membranes were obtained by electrospinning and characterized by SEM and thermal anal. The polymer membranes showed a random fiber distribution with a mean diam. of 1 μm (±300 nm). Differential scanning calorimetry (DSC) expts. showed that the membranes had a glass transition, cold crystn., and melting temps. of 54, 90, and 151°, resp. The kinetic study of thermal degrdn. of PLA under a nitrogen atm. was performed by means of thermogravimetry (TGA). It was found that the thermal decompn. kinetics of PLA could be interpreted in terms of a multi-step degrdn. mechanism. Several theor. models were applied to the TGA data. The activation energies obtained by the Broido and Ozawa-Flynn-Wall (OFW) models were in good agreement with the value of the activation energy calcd. by the Kissinger method.
- 21Jenkins, R.; Snyder, R. L. Introduction to X-ray powder diffractometry; Wiley: 1996.Google ScholarThere is no corresponding record for this reference.
- 22Uchino, K. Ferroelectric Devices, 2nd ed.; CRC Press: 2009.Google ScholarThere is no corresponding record for this reference.
- 23Li, M.; Wondergem, H. J.; Spijkman, M.-J.; Asadi, K.; Katsouras, I.; Blom, P. W. M.; de Leeuw, D. M. Revisiting the δ-phase of poly(vinylidene fluoride) for solution-processed ferroelectric thin films. Nat. Mater. 2013, 12, 433, DOI: 10.1038/nmat3577Google Scholar23https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC3sXktVKhu7o%253D&md5=386d699071734ea63d122a6e869ade3eRevisiting the δ-phase of poly(vinylidene fluoride) for solution-processed ferroelectric thin filmsLi, Mengyuan; Wondergem, Harry J.; Spijkman, Mark-Jan; Asadi, Kamal; Katsouras, Ilias; Blom, Paul W. M.; de Leeuw, Dago M.Nature Materials (2013), 12 (5), 433-438CODEN: NMAACR; ISSN:1476-1122. (Nature Publishing Group)Ferroelec. poly(vinylidene-fluoride) (PVDF) has, in the past, been proposed as an ideal candidate for data storage applications as it exhibits a bistable, remanent, polarization that can repeatedly be switched by an elec. field. However, fabrication of smooth ferroelec. PVDF thin films, as required for microelectronic applications, is a long-standing problem. At present, the copolymer of PVDF with trifluoroethylene P(VDF-TrFE) is used, but the stack integrity and the limited thermal stability of its remanent polarization hamper large-scale integration. Here we show that smooth neat PVDF films can be made at elevated substrate temp. On applying a short elec. pulse the ferroelec. polarδ-phase is formed, an overlooked polymorph of PVDF proposed 30 years ago, but never exptl. verified. The remanent polarization and coercive field are comparable to those of the copolymer. The enhanced thermal stability of the polarization is directly related to the high Curie temp., whereas the ferroelec. properties are related to the mol. packing as derived from the refined crystal structure. The replacement of P(VDF-TrFE) by the commodity polymer PVDF may boost large-scale industrial applications.
- 24Ballato, A. Piezoelectricity: Venerable Effect, Modern Thrusts; Defense Technical Information Center: 1994.Google ScholarThere is no corresponding record for this reference.
- 25Kholkin, A. L.; Pertsev, N. A.; Goltsev, A. V. Piezoelectricity and Crystal Symmetry. In Piezoelectric and Acoustic Materials for Transducer Applications; Safari, A.; Akdoğan, E. K., Eds.; Springer US: Boston, MA, 2008; pp 17– 38.Google ScholarThere is no corresponding record for this reference.
- 26Sencadas, V.; Ribeiro, C.; Bdikin, I. K.; Kholkin, A. L.; Lanceros-Mendez, S. Local piezoelectric response of single poly(vinylidene fluoride) electrospun fibers. Phys. Status Solidi A 2012, 209 (12), 2605, DOI: 10.1002/pssa.201228136Google Scholar26https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC38Xht1agsbzK&md5=dabef3ef11e39e1877bc60cac0ec1bf9Local piezoelectric response of single poly(vinylidene fluoride) electrospun fibersSencadas, V.; Ribeiro, C.; Bdikin, I. K.; Kholkin, A. L.; Lanceros-Mendez, S.Physica Status Solidi A: Applications and Materials Science (2012), 209 (12), 2605-2609CODEN: PSSABA; ISSN:1862-6300. (Wiley-VCH Verlag GmbH & Co. KGaA)It is shown that electrospun poly(vynilidene fluoride) nanofibers are fully poled right after prepn. and show β-phase contents of ∼70%, therefore being able to be implemented into electroactive devices without further processing steps. Further, the local piezoelec. properties of individual electrospun fibers have been studied by piezoresponse force microscopy. Piezoelec. response, polarization switching, and nanoscale patterning of the fibers have been demonstrated.
- 27Karan, S. K.; Bera, R.; Paria, S.; Das, A. K.; Maiti, S.; Maitra, A.; Khatua, B. B. An Approach to Design Highly Durable Piezoelectric Nanogenerator Based on Self-Poled PVDF/AlO-rGO Flexible Nanocomposite with High Power Density and Energy Conversion Efficiency. Adv. Energy Mater. 2016, 6 (20), 1601016, DOI: 10.1002/aenm.201601016Google ScholarThere is no corresponding record for this reference.
- 28Nunes-Pereira, J.; Sencadas, V.; Correia, V.; Rocha, J. G.; Lanceros-Méndez, S. Energy harvesting performance of piezoelectric electrospun polymer fibers and polymer/ceramic composites. Sens. Actuators, A 2013, 196, 55– 62, DOI: 10.1016/j.sna.2013.03.023Google Scholar28https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC3sXotl2qu7k%253D&md5=7d1b81caf182b2843dd0fb0d134a0444Energy harvesting performance of piezoelectric electrospun polymer fibers and polymer/ceramic compositesNunes-Pereira, J.; Sencadas, V.; Correia, V.; Rocha, J. G.; Lanceros-Mendez, S.Sensors and Actuators, A: Physical (2013), 196 (), 55-62CODEN: SAAPEB; ISSN:0924-4247. (Elsevier B.V.)The energy harvesting efficiency of electrospun poly(vinylidene fluoride), its copolymer vinylidene fluoride-trifluoroethylene and composites of the later with barium titanate ceramic fillers on interdigitated electrodes has been investigated. Ceramic fillers of 500 (tetragonal), 100 (cubic) and 10 nm (cubic) have been used. Further, a study of the influence of the electrospinning processing parameters on the av. size of the composites fibers has been performed. It is found that the best energy harvesting performance was obtained for pure poly(vinylidene fluoride) fibers, with power outputs up to 0.02 μW and 25 μW under low and high mech. deformation. The copolymer and the composites show reduced power output mainly due to increased mech. stiffness, the power output of the composites being better for the nonpiezoelectic smaller fillers. The obtained values, among the largest found in the literature, the easy processing and the low cost and robustness of the polymer, demonstrate the applicability of the developed system.
- 29Xu, S.; Qin, Y.; Xu, C.; Wei, Y.; Yang, R.; Wang, Z. L. Self-powered nanowire devices. Nat. Nanotechnol. 2010, 5 (5), 366– 373, DOI: 10.1038/nnano.2010.46Google Scholar29https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC3cXls12isLY%253D&md5=352accda31422d3148ee34c13f435afdSelf-powered nanowire devicesXu, Sheng; Qin, Yong; Xu, Chen; Wei, Yaguang; Yang, Rusen; Wang, Zhong LinNature Nanotechnology (2010), 5 (5), 366-373CODEN: NNAABX; ISSN:1748-3387. (Nature Publishing Group)The harvesting of mech. energy from ambient sources could power elec. devices without the need for batteries. However, although the efficiency and durability of harvesting materials such as piezoelec. nanowires have steadily improved, the voltage and power produced by a single nanowire are insufficient for real devices. The integration of large nos. of nanowire energy harvesters into a single power source is therefore necessary, requiring alignment of the nanowires as well as synchronization of their charging and discharging processes. Here, we demonstrate the vertical and lateral integration of ZnO nanowires into arrays that are capable of producing sufficient power to operate real devices. A lateral integration of 700 rows of ZnO nanowires produces a peak voltage of 1.26 V at a low strain of 0.19%, which is potentially sufficient to recharge an AA battery. In a sep. device, a vertical integration of three layers of ZnO nanowire arrays produces a peak power d. of 2.7 mW/cm3. We use the vertically integrated nanogenerator to power a nanowire pH sensor and a nanowire UV sensor, thus demonstrating a self-powered system composed entirely of nanowires.
- 30Stefanescu, D. M. Handbook of Force Transducers: Principles and Components; Springer: Berlin Heidelberg, 2011.Google ScholarThere is no corresponding record for this reference.
- 31Qiu, A.; Li, P.; Yang, Z.; Yao, Y.; Lee, I.; Ma, J. A Path Beyond Metal and Silicon:Polymer/Nanomaterial Composites for Stretchable Strain Sensors. Adv. Funct. Mater. 2019, 0 (0), 1806306, DOI: 10.1002/adfm.201806306Google ScholarThere is no corresponding record for this reference.
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