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Title: Progress in the application of triboelectric nanogenerators (TENG) in medical and health monitoring


Summary:


Triboelectric nanogenerators (TENG), as a revolutionary energy harvesting technology, have attracted increasing attention from the scientific community because of their ability to efficiently convert mechanical energy into electrical energy. The purpose of this paper is to systematically review the application progress of TENG in the field of medical and health monitoring. Based on triboelectric and electrostatic induction effects, TENG generates electrical energy through contact separation or sliding mode, and its flexibility in structural design, diversity of material selection, cost-effectiveness, and high conversion efficiency make it a significant advantage in the healthcare field.


The article first outlines the four basic modes of operation of TENG: vertical contact separation mode, horizontal sliding mode, single electrode mode and independent layer mode, and elaborates on how they work. Subsequently, the article deeply discusses the application examples of TENG in wearable health monitoring devices, implantable medical devices and environmental health monitoring, and fully demonstrates the broad potential of TENG technology in medical and health monitoring. In addition, the advantages of TENG technology, including its self-power supply characteristics, high sensitivity, and good biocompatibility, are analyzed, and the challenges are also pointed out, such as improving long-term stability, improving energy conversion efficiency, and enabling system integration. Through the case study, this paper further illustrates the application effect of TENG in the actual medical and health monitoring system.


Finally, the paper looks forward to the future development direction of TENG technology, including the development of new materials, the application of intelligent algorithms, and the integration with other energy harvesting technologies. The purpose of this paper is to provide researchers and developers with in-depth insights into the application of TENG technology in the field of healthcare monitoring, and to guide future research directions, with a view to promoting the development and innovation of related technologies.


Keywords: Triboelectric Nanogenerator (TENG), Medical Health Monitoring, Self-Powered Sensors, Energy Harvesting


1. Introduction


With the advent of wearable technology and the Internet of Things (IoT)
IoT
The demand for health monitoring equipment is growing. These devices are able to monitor the user's physiological parameters such as heart rate, blood pressure, and body temperature in real time, which is of great significance for disease prevention, early diagnosis, and treatment. However, traditional health monitoring devices often rely on an external power source, which limits their portability and long-term applicability.


As a new type of energy harvesting technology, triboelectric nanogenerators (TENG) have attracted extensive attention because they can efficiently convert mechanical energy generated by human movement or natural waves and wind into electrical energy. TENG technology provides a self-powered solution for healthcare monitoring devices and is expected to drive the development of wearables and implantable medical devices.


TENG technology is based on the principles of triboelectric and electrostatic induction, capable of harvesting energy from human movement, breathing, and even bloodstream. This type of energy harvesting provides a continuous supply of energy for medical and health monitoring devices, reducing reliance on traditional batteries. In addition, TENG has also expanded its application direction in water quality monitoring and microbial disinfection. In addition, TENG devices often have the advantages of low cost, ease of fabrication, and good biocompatibility, making them show great potential for application in the healthcare field.


The purpose of this review is to discuss the application progress of TENG technology in medical and health monitoring, analyze its advantages and challenges, and look forward to the future development direction. Through a systematic analysis of the existing literature, this paper will provide researchers and developers with in-depth insights to guide future research and product development.


2. TENG Technology Principle


2.1 Triboelectric and electrostatic induction principle


The phenomenon of triboelectric initiation describes the transfer of charge between two different materials during contact and separation. This pass is due to the difference in the affinity of the atoms of the two materials for electrons. When two materials come into contact, the material with a stronger electron affinity attracts electrons from the material with a weaker affinity, causing the former to be negatively charged and the latter to be positively charged, resulting in static electricity.


Electrostatic induction occurs when a charged object approaches an uncharged conductor. The charges inside the conductor are redistributed so that the end of the conductor close to the charged object has the opposite charge to the charged object, and the end away from the charged object has the opposite charge. This phenomenon is caused by the interaction forces between the charges.


Triboelectric nanogenerators (TENG) are based on these two physical phenomena to convert mechanical energy into electrical energy. When two materials with different electron affinities come into contact with each other, electrons are transferred from the weaker affinity material to the stronger material, resulting in one material being negatively charged on the surface and the other positively charged. As these two charged surfaces separate, a potential difference forms between them, triggering electrostatic induction. The potential difference induces the formation of opposite charges on nearby electrodes, creating an electric field that prompts the redistribution of electrons between the electrodes and the charged surface.


As the two charged surfaces continue to separate, the potential difference increases, resulting in charge accumulation on the electrode. If an external circuit is connected, electrons will flow from the high-potential region to the low-potential region through the circuit, forming an electric current and realizing the conversion of mechanical energy to electrical energy. TENG continuously generates electrical energy through periodic contact and separation or other forms of mechanical movement. This energy conversion process is reversible, and when the circuit is disconnected, the electric field disappears and the charge returns to the original charged surface in preparation for the next energy conversion cycle.


2.2 The basic structure and working mode of TENG


Triboelectric nanogenerators (
TENG2012
years after the launch

Tremendous progress has been made in the field of energy harvesting and self-driving sensing.
TENG
Using triboelectric and electrostatic induction to effectively convert mechanical energy into electrical energy, it captures ubiquitous mechanical energy and brings innovative solutions to tomorrow's energy challenges. Next, we'll dive in
TENG
of the five modes of work and their applications


(I.) Vertical Contact-Separation Mode: When two materials and materials with different electron affinities come into contact, electrons are transferred from M1 with a weaker affinity to a stronger oneM2, causing M1 to be positively charged and M2 to be negatively charged. When separated, the contact surface charge is separated, and M1 and M2 remain unchanged. The electrodes E1 and E2 on the back of each friction layer collect their respective charges when the friction layer touches againThe external circuit is connected, and electrons flow from E1 to E2 to balance the potential difference, resulting in alternating current. This periodic contact and separation drives a continuous charge recombination that converts mechanical energy into electrical energy. The generated electrical energy can be used to supply power to the device by an external circuit load L connected between E1 and E2. During contact and separation, the direction of the current changes accordingly. This mode of TENG is particularly suitable for periodic movements such as keystrokes or vibrational energy harvesting. (Figure a).


(II.) Horizontal Slip Mode: When two friction layers with different electron affinities come into contact, electrons are transferred from M1 with a weaker affinity to a stronger M2, resulting in M1 being positively charged and M2 negatively charged. As the two layers slide relative to each other in parallel directions, the triboelectric charge separates on the surface and is located at the electrodes E1 and E2 of the two tribographic layers, respectivelyto produce a potential difference. This potential difference drives electrons to flow from E1 to E2 through an external circuit load L, forming an electric current that converts mechanical energy into alternating current (AC) through periodic sliding and separation. L is connected between E1 and E2 to collect and utilize the generated electrical energy. This mode of TENG is suitable for energy harvesting in long-distance reciprocating movements, such as the friction of sliding parts of a machine or the sole of a shoe against the ground. By optimizing the design, such as adding mechanical components such as springs, the output performance of the TENG can be improved to better capture and convert mechanical energy. The TENG in horizontal sliding mode is suitable for energy harvesting in plane reciprocating motion.


(III.) Single-electrode mode: In this mode, material M1 acts as a substrate and comes into contact with the friction layer F, and when F comes into contact with M1, charge transfer occurs due to their different electron affinities, so that F has a negative charge and M1 has a positive charge. Usually only one electrode E is connected to F, and this electrode is connected to the external circuit load L. When F is in contact with E, the free electrons on E will be repelled or attracted by the charge on F due to electrostatic induction, thus repelling or attracting E and Lbetween the formation of electric currents. As the friction layer periodically comes into contact with and separates from the electrodes, e.g. by pressing, vibrating, or sliding, TENG generates alternating current (AC). External circuit loads can be LED lights, sensors, or other electronic devices that can directly use the electrical energy generated by TENG. This mode of TENG is suitable for self-propelled systems, such as powering wearables using the friction between the ground and shoes while walking. The single-electrode mode TENG is suitable for situations where one of the friction layers can be used as an electrode, such as the surface of a floor, tabletop, or other large object.


(IV.) Independent Layer Mode: A triboelectric nanogenerator (TENG) in independent triboelectric layer mode passes through two independent triboelectric layers F1 and F2 and an electrode Eto convert mechanical energy into electrical energy. When F1 and F2 come into contact, charge transfer occurs due to their difference in electronic affinity, resulting in F1 being positively charged and F2 negatively charged. With the separation of the two layers, the charge remains on their respective surfaces. This separation can be caused by external mechanical forces such as vibration, pressure, or wind. When F1 is far away from E, F1 and F2 will induce opposite charges on E. E collects these induced charges, which accumulate on E as the relative position between F1 and F2 and E changes. The outer circuit load L is connected to electrode E and is used to utilize the generated electrical energy. Through periodic contact and separation, TENG continuously converts mechanical energy into alternating current (AC). This mode enables energy harvesting in a non-contact state, making it suitable for applications where remote energy transmission devices or direct contact needs to be avoided.


(V.) Free rotation mode: The free rotation mode consists of a rotating disc D made of triboelectric material and a set of stationary electrodes E. When disc D rotates, the triboelectric effect causes opposite charges on the surfaces of D and electrode E. As D continues to rotate, these charges separate, creating a potential difference between D and E, which in turn drives electrons to flow through an external circuit, generating an electric current. The current is passed through an external load L, which supplies power to small electronic devices or charges batteries. The periodic rotation of D causes this energy conversion process to be repeated over and over again, continuously generating electrical energy. This mode of TENG effectively collects energy from rotational motion, and is suitable for a variety of scenarios that require rotational energy conversion.


3. Application of TENG in medical and health monitoring


3.1 Wearable health monitoring devices


TENG technology has shown great potential in wearable health monitoring devices, especially in the areas of pulse monitoring, blood pressure monitoring, and body temperature monitoring. By integrating TENG into wearable devices, the mechanical energy generated by human movement can be used to power the device for self-powered health monitoring.


3.1.1 Pulse monitoring


Pulse monitoring is an important branch of the healthcare field that measures the pulse of the body's arteries to assess the heart's working status and blood circulation. With the development of wearables and flexible electronics, based on
TENG
Technological pulse monitoring devices have received a lot of attention for their comfort and portability.


Figure 3(a) Schematic diagram of the preparation process of silk nanoparticles (SNRs). (b) Cell viability of Schwann cells (SCs) after 2, 4, and 6 days of culture on different matrices. (c) Dependence of the output voltage and PD on different external resistors. (d-i) Cellular response and post-treatment (RSFF-p) on SNRF and regenerated silk fibroin membranes. (j) The output voltage of TENG at a frequency of 3 Hz. (k) Output current. (l) At a frequency of about 5 Hz, the output voltage of the TENG is tapped by hand.


Niu et al. developed a pulse-driven biotriboelectric nanogenerator based on silk nanoribbons, and silk fibroin nanoribbons (SNRs) were used in the study, which consists of SNRFs, RSFF and Mg composition, Figure 3a is its preparation process, first DS, TEMPO, NaBr and NaClO were mixed in deionized water and stirred. Next, NaOH is added to adjust the pH to 10 to 10.5 so that DS is converted to silk microfibers, and againRinse with deionized water to remove residual solvent and silk fibroin. The serine hydroxyl group is oxidized in two steps, first converted to aldehyde, and then oxidized to carboxylate group, which enhances the electrostatic repulsion on the surface of the silk and promotes the delamination of the material, and the weak interface of DS is broken due to solvent oxidation. Finally, the aqueous solution containing silk microfiber was sonicated to obtain a single SNR that was uniformly dispersed to form a stable aqueous suspension. Figure 3d-i shows Schwann cells cultured on different matrices (SNRF, RSFF, and coverslips)2Cell viability after 4 and 6 days, as assessed by MTT experiments, showed that cell viability on SNRF was significantly higher than that on RSFF and coverslips, indicating SNRFHas a better ability to support cell proliferation. Figure 3j shows that the output voltage of the TENG is about 13 V at 3 Hz; Figure 3k shows an output current of approximately 0.46μA measured with a multimeter at the same 3 Hz frequency; Figure 3l shows the output voltage of the TENG up to approx. 41.64 V under manual tapping (approx. 5 Hz frequency); Figure 3b shows the variation of the output voltage and power density (PD) of the TENG at different external resistances, where the instantaneous maximum output power density is approximately at a load resistance of 100 M Ω86.7 mW/m²。 Together, these graphs illustrate the excellent performance of the bio-TENG in terms of voltage, current, and power density.


3.1.2 Blood pressure monitoring


Blood pressure monitoring is one of the key means to assess cardiovascular health status, for the diagnosis and treatment of hypertension

and prevention play an important role. With the development of technology, blood pressure monitoring technology has developed from traditional occasional blood pressure measurement to ambulatory blood pressure monitoring (
ABPM
), which provides more continuous and comprehensive blood pressure information.


Figure 4(a) Schematic diagram of sensor array structure and carbide filament image. (b) Relative change in sensor resistance versus applied strain. (c) and (d) the relative change in resistance of the sensor array when suppressed at different positions. (e) and (f) comparison charts of radial pulse waves collected before and after 30 days were used.


Li et al. developed an intelligent blood pressure and cardiac function monitoring system based on a highly sensitive strain sensor array and a deep learning neural network. This sensor is based on the carbide silk fabric CSG, as shown in Figure 4a, the carbide silk georgette CSG with twisted warp and twisted weft is used as the active layer,Laser-cut nickel fabric with high conductivity is used as the electrode, and the ultra-thin Ecoflex layer is used for encapsulation. The entire sensor array exhibits excellent flexibility, good biocompatibility, and high structural and chemical stability. Figure 4b shows the change in resistance of the strain sensor relative to the applied strain, demonstrating high linearity, demonstrating the high sensitivity and good linear response of the sensor over a strain range of 0 to 200%. Figures 4c and d show that at least one sensor is able to produce a distinct electrical response when pressed against the sensor array at different positions, demonstrating high isotropy. Figure 4d shows the resistance of the sensor over time when a small strain of 0.5% is applied, and it can be observed that the sensor has a fast response (40 ms) and recovery time (). 80 ms). By comparing the pulse waveforms in Figure 4e and f, it can be seen that the sensor has maintained stable performance in long-term applications with no significant signal attenuation or distortion, indicating that the sensor has good long-term stability and durability. Based on the above performance, the system can provide continuous and reliable monitoring of cardiovascular status, which is helpful for the early diagnosis and treatment of cardiovascular diseases.


3.1.3 Body temperature monitoring


Body temperature monitoring is an important branch of the medical and health field, which involves the continuous measurement of human body temperature, which is of great significance for early detection and prevention of diseases. With the development of technology, body temperature monitoring technology has evolved from traditional contact thermometers to wireless body temperature monitoring systems, which can provide more continuous and comprehensive body temperature information.

5.aTIF
Schematic diagram of manufacturing. (
bTIF
Optical photographs. (
c
) use
TIF
Schematic diagram of the temperature sensing mechanism


Li et al. developed a multifunctional sensor based on ionic gels for body temperature monitoring and joint motion detection, which is based on ionic liquids (ILs) and ionic gels of commercial thermoplastic polyurethane (TPU) fibers, prepared by impregnation method. The EMIM+ and TFSI content in T IF can be adjusted by controlling the heating temperature, as shown in FigTIF at different temperatures was prepared as shown in 5a. As shown in Figure 5b, the obtained TIF retains good flexibility and elasticity, and also maintains the transparency of the TPU fibers. Figure 5c illustrates that when a smart fiber (TIF) is stimulated by temperature, the degree of dissociation and mobility of ion pairs in the ionic gel increases with increasing temperature, which means that at higher temperatures, the ions in the ionic gel are able to move more quickly, changing the conductivity of the material. Figures 5d and e show TIFS prepared at 90 °C at 20 to 40 ◦CThe impedance change and temperature response over the temperature range demonstrate the sensitivity of the sensor to temperature changes, reflecting the sensor's high temperature sensitivity (2.73%°C⁻¹) and sufficient resolution (0.1 °C).


In summary, the ionic gel-based multifunctional sensor proposed in this paper provides a high-sensitivity and high-resolution monitoring method for body temperature monitoring, which is helpful to improve the quality and convenience of personal health monitoring, demonstrating TENGPotential for wide range of applications in personal health management and medical monitoring.


3.2 Implantable Medical Devices


The application of TENG technology in the field of implantable medical devices, especially in cardiac pacemakers and drug delivery systems, shows great potential and innovation.


3.2.1 Cardiac pacemakers

TENG
The application of technology in pacemakers is an area of innovation that aims to provide a self-powered solution for pacemakers. A pacemaker is an implanted medical device used to treat arrhythmias, usually powered by batteries.
TENG
Technology is able to convert mechanical energy, such as a beating heart, into electrical energy to provide a continuous source of energy for pacemakers, reducing or eliminating the need to replace batteries.


Figure 6(a-c) The open-circuit voltage, transfer charge, and short-circuit current of the I-TENG driven by a linear motor. (d) Peak power density at different load resistances. (e) I-TENG stability test. (f) Statistical analysis of minimum voltage, maximum voltage and voltage difference. (g) Statistical analysis of the difference between the minimum transfer charge, the maximum transfer charge, and the transfer charge.


In one study, Ouyang et al. developed a symbiotic pacemaker (SPM) that is able to obtain energy from the heart's beating to provide electrical energy to the pacemaker itself. The energy-harvesting part of this pacemaker is an implantable triboelectric nanogenerator (I-TENG), which consists of two triboelectric layers, a support structure, and a shell with two encapsulation layers, which is extremely flexible and biocompatible. Figure 6a-c illustrates the performance of the I-TENG in vitro testing, reflecting the high output performance of the device. Figure 6d illustrates the high power density of the I-TENG. Figure e shows the stability test results of I-TENG after 100 million mechanical stimulation cycles, demonstrating its good durability. Excellent stability and high power output performance in living organisms. Figure f-g illustrates the energy harvesting and electrical properties of I-TENG in vivo, and it can be concluded that the energy produced by each cardiac exercise cycle is 0.495 microjoules, Energy above the threshold for cardiac pacing.


In another study, the scientists demonstrated an inertia-driven, in-vivo triboelectric nanogenerator (ITENG) capable of using body motion and gravity to generate electrical energy. This ITENG used amine-functionalized polyvinyl alcohol (PVANH2) and perfluoroalkoxy (PFA) as triboelectric materials, successfully operated in animals, and collected real-time output voltage data. The results of the study showed that the device was able to harvest enough energy to charge the pacemaker's battery.


These studies show that the application of TENG technology in cardiac pacemakers has great potential to provide a self-propelled energy solution for pacemakers, reducing the risk and inconvenience of patients needing to surgically replace batteries due to battery depletion. With the further development of technology, more self-powered implantable medical devices may be developed in the future to provide more guarantees for people's healthy life.


3.2.2 Drug delivery systems


The application of TENG technology in drug delivery systems is an area of innovation that powers drug delivery systems by converting biomechanical energy into electrical energy. The following are the applications of TENG technology in drug delivery systems:


1. Targeted therapy:


exploit
TENG
technology, researchers have developed advanced drug delivery systems that enable self-regulating, on-demand, and controlled-release drug delivery, especially for targeted therapies such as cancer treatment, wound healing of infections, and tissue regeneration


Figure 7(a) Schematic diagram of the mechanism of drug loading and release by electrical stimulation. (b) Electroporation-mediated gene delivery strategies. (c) TENG-mediated electroporation drug delivery system. (d) Stability of Voc over 30,000 cycles.


Muhammad Ikram has developed an advanced triboelectric nanogenerator-driven drug delivery system for targeted therapy, and Figure 7a shows how the TENG system can be precise and on-demand through the use of human heatThe drug is released to the target cells. Figure 7b-c illustrates the self-powered TENG-mediated drug delivery system, including the electroporation-mediated gene delivery strategy and the TENG-mediated electroporation drug delivery system, both of which are indicatedDrug release can be automatically adjusted in response to electrical stimulation. Figure 7d shows the stability of the Voc over 30,000 cycles, demonstrating the stability of the TENG system.


2. Biomechanical Motion-Driven Drug Delivery:

TENG
Technology can convert the energy of human movement into electrical energy that can be used to drive drug delivery devices, such as transdermal drug delivery systems. This self-powered, transdermal drug delivery system enables continuous drug delivery, reducing the risk of peaks and valleys in drug concentrations in the body


Figure 8.( a) TENG structural design. (b) Open-circuit voltage stability test chart. (c) Nanoneedle array + TENG. (d) Plane + TENG. (e) Nanoneedle arrays only.


Liu et al. developed a TENG-based electroporation system for in vitro and in vivo drug delivery. The system successfully delivers exogenous materials such as large and small molecules and siRNAs into different cell types, including difficult-to-transfect primary cells, with delivery efficiency and cell viability exceeding 90%. In the study, the TENG disc consisted of a rotor with a radially arranged copper strip as a friction layer, a layer of polytetrafluoroethylene (PTFE) on the stator as another friction material, and a stator with a complementary radially arranged copper layer The strip acts as an electrode (Fig. 8a), a design that allows TENG to generate electrical energy through the triboelectric effect generated by the contact and separation between the copper strip and the PTFE as the rotor rotates. Figure 8b illustrates the stability of the open-circuit voltage of the TENG after 30,000 cycles. This demonstrates the ability of TENG to maintain a stable electrical output over long-term use, which is critical to ensure the continuous operation of the drug delivery system and the consistency of drug delivery. Figure 8c shows that the drug successfully penetrated into the dorsal skin of nude mice at a depth of 23μm after combining TENG and nanoneedle array electrode treatment. In contrast, Figures 8d and 8e show the drug penetration depths using planar electrodes alone plus TENG pulses and nanoneedle array electrodes alone, respectively11μm and 6μm. Comparison of these data shows that the combination of TENG and nanoneedle array electrodes significantly increases the depth of drug penetration by more than three times that of nanoneedle array electrodes alone, thus demonstrating the significant advantages of TENG-driven electroporation systems in improving the efficiency and depth of transdermal drug delivery.


3. Smart Drug Delivery:


The intelligent drug delivery system is a system that realizes the accurate, efficient and safe delivery of drugs through technological innovation, and its application in the medical field is promoting a revolutionary progress.

these systems

By precisely controlling the rate and location of drug release, the therapeutic effect is improved while reducing damage to normal cells and reducing side effects. It can also adjust the dosing strategy according to the patient's specific condition and physiological indicators, and achieve personalized treatment.


Figure 9(a) Formation and drug release processes of MXene-based hydrogel systems. (b) No material, MXene-based hydrogel, Hydrogel@AgNPs, Hydrogel@AgNPs+NIR and other different talentsPhotographs of wound healing processes in diabetic rats at different time points (0, 3, 6, 9, and 12 days) were processed. (c) Statistics of wound area. (d) Number of CD163 cells.


The researchers have developed a hydrogel system based on two-dimensional MXene materials that responds to light and magnetic fields and is able to control the release of drugs. Figure 9a illustrates the system consisting of MXene encapsulated magnetic nanoparticles (MNPs@MXene) and poly(N-isopropylacrylamide)- The hydrogel is composed of alginate (PNIPAM-alginate) double network, and the contraction of the hydrogel is controlled by external stimuli such as NIR radiation and alternating magnetic field, so as to precisely control the drug AgNPof release. The progression of wound healing, including the speed of wound closure and the inflammatory response, can be visually observed in Figure 9b, and Figure 9c shows the wound area statistics of diabetic rats in different treatment groups to quantify the progress of wound healing, Figure 9d shows the number of CD163 cells (a surface marker of macrophages) in different groups to infer an increase or decrease in inflammation, which together demonstrates MXeneThe base hydrogel system has demonstrated desirable therapeutic effects in chronic diabetic wound healing models, particularly in reducing inflammation, promoting tissue regeneration, and angiogenesis.


In summary, the application of TENG technology in drug delivery systems shows great potential and innovation, and provides new ideas and technical support for the development of new self-powered and intelligent drug delivery systems.


3.3 Environmental health monitoring


The application of TENG technology in environmental health monitoring, especially in air and water quality monitoring and microbial disinfection, shows great potential.

3.3.1
Water quality monitoring


Figure 10(a) Structure of the SOS system. (b) Self-powered water texture measurement test excited by the 3-DOF platform. (c-e) Voltage history of the capacitor during self-powered testing. (f, g) Random wave slots. (h.i) The real marine environment. (j, k) Photographs and voltage history of the self-powered sensing process.


TENG technology is used to develop self-powered water quality monitoring systems. For example, Wang et al. invented a multi-tunnel gate electrode for wave energy harvesting and a rolling-mode triboelectric nanogenerator with reverse charge enhancement to monitor water quality by using a self-powered ocean sensing system System, abbreviated as SOS system), the system architecture is shown in Figure 10a, including stacked MO-TENG units, power management modules (PMMs), charging capacitors, voltage regulators, low-power SoCs, long-range communication modules, water quality sensors, and receivers. Figure 10b-e illustrates the self-supplied water quality monitoring performance of the SOS system under external excitation, including the voltage history of the storage capacitor and the charging and discharging cycles of the capacitor during the self-energy sensing process. Figure f-k shows a MO-TENG buoy deployed in a real-world marine environment capable of harvesting wave energy and enabling self-powered water quality monitoring and data transmission through an SOS system. Together, the SOS system uses MO-TENG to collect energy from ocean waves, and uses this energy to drive water quality sensors and wireless communication modules for real-time monitoring and data transmission of water quality.

3.3.2
Microbial disinfection


Figure 11.( a) Schematic diagram of the S-TENG structure. (b) Schematic diagram of the periodic rotation of the S-TENG. (c) Schematic diagram of the rotation speed, output voltage and output current of the S-TENG under manual drive operation. (d) Use various probes powered by S-TENG (N2 gas for ·O2- and H2O2, benzoic acid; BA is used for ·OH and nitrobenzene; NB is used for ·OH and ·Cl) to conduct an oxidized species survey. (e) Schematic diagram of bacterial damage after S-TENG disinfection with Cu3P NW-Cu and Cu3P@SnO2 NW-Cu.


In the field of microbial disinfection, TENG technology is used to develop self-powered disinfection systems. Huo et al. developed a novel disinfection system using a self-powered supercoil-mediated rotational triboelectric nanogenerator (S-TENG) as a power source to drive a novel oxidation-assisted electroporation mechanism, shown in Figure 11aStructure and operating principle of the S-TENG, where 11c particularly demonstrates the ultra-fast rotational speed achieved by the S-TENG under manual drive operation (Fig. 11b) and output voltage and current for inactivation of bacteria and viruses in water. Figure 11d quantifies the type of oxidizing species produced by adding different radical probes to eliminate specific oxidizing species and comparing the disinfection efficiency with and without the addition of these probes. These results confirm that S-TENG is able to generate both enhanced local electric field and oxidizing substances during the disinfection process, achieving efficient disinfection performance. Figure 11d illustrates the in-situ dual staining method, which can be seen using SYTOX Green and PI to distinguish between repairable and fatal damage effects on bacterial membranes The majority of bacteria treated with Cu 3P@SnO2 NW-Cu at fast flow rates (20 mL/min) suffered fatal damage, demonstrating the ability of the S-TENG disinfection method to achieve effective microbial inactivation at fast flow rates through this design。 In summary, the S-TENG water treatment method provides a potential solution to the much-needed water disinfection needs.


4. Advantages and challenges


4.1 Advantages


TENG technology offers several significant advantages in the field of healthcare monitoring, which make it an ideal choice in this field.


(I.) Self-powered features: TENG is able to convert mechanical energy into electrical energy, providing a continuous energy supply for medical and health monitoring equipment, reducing the dependence on traditional batteries, thereby reducing the maintenance cost of equipment and the risk of environmental pollution.


(II.) HIGH SENSITIVITY: TENG'S HIGH SENSITIVITY TO MICRO-MECHANICAL MOVEMENTS ALLOWS IT TO DETECT THE BODY'S WEAK PHYSIOLOGICAL SIGNALS, SUCH AS SMALL CHANGES IN PULSE, BLOOD PRESSURE, AND BODY TEMPERATURE, WHICH ARE ESSENTIAL FOR EARLY DISEASE DIAGNOSIS AND HEALTH MONITORING.


(III.) GOOD BIOCOMPATIBILITY: TENG is typically made of biocompatible materials that can be safely in contact with human tissues, reducing the immune response and inflammation that implantable devices may cause.


(IV.) COST-EFFECTIVENESS: TENG'S RELATIVELY LOW MANUFACTURING COST AND LOW LONG-TERM COST OF USE DUE TO ITS SELF-POWERED NATURE MAKE TENG TECHNOLOGY HAVE A WIDE RANGE OF APPLICATION POTENTIAL IN THE FIELD OF MEDICAL AND HEALTH MONITORING.


(V.) Flexibility and customizability: TENG's structural design is flexible and can be customized according to different application needs, which allows TENG technology to adapt to the design requirements of various medical and health monitoring equipment.


4.2 Challenges


Although TENG technology has significant advantages in the field of healthcare monitoring, it also faces some challenges that require further research and development to overcome.


(I.) Long-term stability: The long-term stability of TENG is the key to its wide application in the field of medical and health monitoring. Material improvements and structural optimization are needed to improve the durability and long-term stability of TENG.


(II.) ENERGY CONVERSION EFFICIENCY: WHILE TENG IS ABLE TO EFFICIENTLY CONVERT MECHANICAL ENERGY INTO ELECTRICAL ENERGY, IN SOME APPLICATIONS, FURTHER ENERGY CONVERSION EFFICIENCY MAY NEED TO BE FURTHER IMPROVED TO MEET THE ENERGY NEEDS OF ENERGY-INTENSIVE MEDICAL DEVICES.


(III.) ENERGY STORAGE AND MANAGEMENT: DESPITE SIGNIFICANT PROGRESS IN ENERGY HARVESTING WITH TENG TECHNOLOGY, HOW TO EFFECTIVELY STORE AND MANAGE THIS ENERGY REMAINS A CHALLENGE. The electrical energy generated by TENG is often intermittent and unstable, which requires the development of efficient energy storage systems and advanced energy management strategies to ensure a continuous and stable power supply.


(IV.) ENVIRONMENTAL ADAPTABILITY: MEDICAL AND HEALTH MONITORING EQUIPMENT MAY BE USED UNDER VARIOUS ENVIRONMENTAL CONDITIONS, AND TENG TECHNOLOGY NEEDS TO HAVE GOOD ENVIRONMENTAL ADAPTABILITY TO ENSURE STABILITY AND PERFORMANCE UNDER DIFFERENT TEMPERATURE, HUMIDITY AND PRESSURE CONDITIONS.


5. Summary and outlook


Triboelectric nanogenerator (TENG) technology has shown great potential in the field of medical monitoring, and its energy harvesting and conversion capabilities have brought new ideas to medical device design. This article reviews the progress of TENG in wearable monitoring devices, implantable medical devices, and environmental monitoring, and discusses its advantages and challenges.


TENG's self-powered nature reduces reliance on conventional batteries, reducing maintenance costs and environmental risks. Its high sensitivity helps to detect weak physiological signals, which is essential for early diagnosis and health monitoring of diseases. TENG's biocompatible materials reduce the risk of immune response and inflammation induced by implantable devices, with low manufacturing and long-term use costs and flexible structural design to accommodate diverse medical needs.


Despite this, the application of TENG in the medical field faces challenges such as stability, energy conversion efficiency and power management. In the future, improvements in TENG technology may involve new materials, intelligent algorithms, and integration with other energy technologies to improve energy efficiency and stability. Combining flexible electronics and nanotechnology, TENG is expected to develop more advanced and versatile medical monitoring devices.


In summary, TENG technology has broad prospects in the field of medical and health monitoring, and it is expected that with the advancement of technology, it will play a more important role in medical monitoring in the future and provide stronger protection for human health.


6. References