Tunable Optical Modulator by Coupling a Triboelectric Nanogenerator and a Dielectric Elastomer

A conjunction system based on triboelectric nanogenerator (TENG) and dielectric elastomer actuator (DEA) is a promising demonstration for the application of TENG in the field of electronic skin and soft robotics. In this paper, a triboelectric tunable smart optical modulator (SOM) has been proposed based on this TENG‐DEA system. The SOM has a very simple structure of an elastomer film and electrodes made of dispersed silver nanowires. Owing to the voltage induced rippling of the elastomer, the output of the TENG for a contact‐separation motion at a velocity ranging from 0.5 to 10 cm s^?1 can decrease the SOM's transmittance from 72% to 40%, which is enough for realizing the function of privacy protection. Meanwhile, an effective operation method is also proposed for this SOM. By serially connecting an accessory DEA to the SOM, an external bias voltage can be applied on the SOM to tune its “threshold” voltage and the output from TENG can smoothly regulate the transmittance on the basis of the bias. The proposed operation method has excellent applicability for all DEA‐based devices, which can promote the practical study of TENG‐DEA system in the field of micro‐electro‐mechanical system and human–robots interaction.     

A Self‐Powered Angle Measurement Sensor Based on Triboelectric Nanogenerator

A self‐powered, sliding electrification based quasi‐static triboelectric sensor (QS‐TES) for detecting angle from rotating motion is reported. This innovative, cost‐effective, simply‐designed QS‐TES has a two‐dimensional planar structure, which consists of a rotator coated with four channel coded Cu foil material and a stator with a fluorinated ethylenepropylene film. On the basis of coupling effect between triboelectrification and electrostatic induction, the sensor generates electric output signals in response to mechanical rotating motion of an object mounted with the sensor. The sensor can read and remember the absolute angular position, angular velocity, and acceleration regardless being continuously monitored or segmented monitored. Under the rotation speed of 100 r min^?1, the output voltage of the sensor reaches as high as 60 V. Given a relatively low threshold voltage of ±0.5 V for data processing, the robustness of the device is guaranteed. The resolution of the sensor is 22.5° and can be further improved by increasing the number of channels. Triggered by the output voltage signal, the rotating characteristics of the steering wheel can be real‐time monitored and mapped by being mounted to QS‐TES. This work not only demonstrates a new principle in the field of angular measurement but also greatly expands the applicability of triboelectric nanogenerator as self‐powered sensors.     

Stretchable‐Rubber‐Based Triboelectric Nanogenerator and Its Application as Self‐Powered Body Motion Sensors

A stretchable‐rubber‐based (SR‐based) triboelectric nanogenerator (TENG) is developed that can not only harvest energy but also serve as self‐powered multifunctional sensors. It consists of a layer of elastic rubber and a layer of aluminum film that acts as the electrode. By stretching and releasing the rubber, the changes of triboelectric charge distribution/density on the rubber surface relative to the aluminum surface induce alterations to the electrical potential of the aluminum electrode, leading to an alternating charge flow between the aluminum electrode and the ground. The unique working principle of the SR‐based TENG is verified by the coupling of numerical calculations and experimental measurements. A comprehensive study is carried out to investigate the factors that may influence the output performance of the SR‐based TENG. By integrating the devices into a sensor system, it is capable of detecting movements in different directions. Moreover, the SR‐based TENG can be attached to a human body to detect diaphragm breathing and joint motion. This work largely expands the applications of TENG not only as effective power sources but also as active sensors; and opens up a new prospect in future electronics.     

Flexible Drug Release Device Powered by Triboelectric Nanogenerator

Drug release devices of small molecules are widely used in cell stimulation, drug delivery, and microenvironment regulation. Herein, a flexible drug release device (FDRD) powered by a triboelectric nanogenerator (TENG) is demonstrated, that has the superiority of low power consumption, flexible structure, and controllable release. In the self‐powered FDRD, the TENG can effectively harvest and transfer biomechanical energy into electricity. With a power management module, the TENG can provide a steady voltage supply for sustainable drug release, and the unique switchable wettability of poly(3‐hexylthiophene) films in Na₂SO₄ aqueous solutions can be regulated. The UV–vis absorption spectra of small molecules including methylene blue, fluorescein sodium, and rhodamine 6G released from the FDRD can be observed and recorded in real time. Furthermore, the releasing rate of conventional salicylic acid with the effect of removing cutin, sterilizing, and diminishing inflammation is also recorded in Na₂SO₄ aqueous solution. With the advantages of flexible structure, and controllable and sustainable release, the self‐powered FDRD is expected to find great potential in wearable medical devices, drug controllable release, and self‐powered therapy.     

Triboelectric Nanogenerator for Harvesting Vibration Energy in Full Space and as Self‐Powered Acceleration Sensor

A spherical three‐dimensional triboelectric nanogenerator (3D‐TENG) with a single electrode is designed, consisting of an outer transparent shell and an inner polyfluoroalkoxy (PFA) ball. Based on the coupling of triboelectric effect and electrostatic effect, the rationally developed 3D‐TENG can effectively scavenge ambient vibration energy in full space by working at a hybridization of both the contact‐separation mode and the sliding mode, resulting in the electron transfer between the Al electrode and the ground. By systematically investigating the output performance of the device vibrating under different frequencies and along different directions, the TENG can deliver a maximal output voltage of 57 V, a maximal output current of 2.3 μA, and a corresponding output power of 128 μW on a load of 100 MΩ, which can be used to directly drive tens of green light‐emitting diodes. Moreover, the TENG is utilized to design the self‐powered acceleration sensor with detection sensitivity of 15.56 V g^‐1. This work opens up many potential applications of single‐electrode based TENGs for ambient vibration energy harvesting techniques in full space and the self‐powered vibration sensor systems.     

Microplasma‐Discharge‐Based Nitrogen Fixation Driven by Triboelectric Nanogenerator toward Self‐Powered Mechano‐Nitrogenous Fertilizer Supplier

Development of novel nitrogen fixation technology is realistically significant for the fertilizer industry and agriculture. Traditional plasma‐induced nitrogen fixation technology is severely limited in some instances because this route generally requires a continuous power input with the features of complicated apparatus fabrication, high cost, nonportability, etc. Herein, a triboelectric nanogenerator (TENG)‐driven microplasma discharge–based nitrogen fixation system is conceived by integrating a high‐voltage output TENG and a discharge reactor. The novel TENG has the capability to generate a high voltage of about 1300 V without additional auxiliary. The generated voltage can induce microplasma discharge under atmospheric environment in the discharge reactor, where nitrogen gas is successfully converted into nitrogen dioxide and nitric acid, and atmospheric nitrogen fixation is therefore realized. The TENG‐driven microplasma discharge‐based nitrogen fixation system can serve as a nitrogenous fertilizer supplier, and correspondingly, NaNO₃ fertilizer is produced via driving the system by human walking stimuli for crop cultivation. A promising and energy‐saving atmospheric nitrogen fixation strategy with environmental friendliness, flexible operation, and high safety is offered.     

Auxetic Foam‐Based Contact‐Mode Triboelectric Nanogenerator with Highly Sensitive Self‐Powered Strain Sensing Capabilities to Monitor Human Body Movement

The first contact‐mode triboelectric self‐powered strain sensor using an auxetic polyurethane foam, conductive fabric, and polytetrafluroethylene (PTFE) is fabricated. Utilizing the auxetic properties of the polyurethane foam, the auxetic polyurethane foam would expand into the PTFE when the foam is stretched, causing contact electrification. Due to a larger contact area between the PTFE and the foam as the foam is stretched, this device can serve effectively as a strain sensor. The sensitivity of this method is explored, and this sensor has the highest sensitivity in all triboelectric nanogenerator devices that are used previously as a strain sensor. Different applications of this strain sensor are shown, and this sensor can be used as a human body monitoring system, self‐powered scale to measure weight, and a seat belt to measure body movements inside a car seat.     

Triboelectric Nanogenerators as a Self‐Powered Motion Tracking System

Motion tracking is a key area of sensor systems for security, transportation, and high‐tech industry. In this work, a self‐powered motion tracking system is developed to monitor moving speed, direction, acceleration, starting and ending positions, and even the moving path of a moving object. Such a system is based on a set of triboelectric nanogenerators (TENGs) that are composed of two friction layers with opposite triboelectric polarities (Kapton and Aluminum) and operates in the sliding mode. Velocities of a moving object are monitored from ?0.1 m s^‐1 to +0.1 m s^‐1 at a step of 0.01 m s^‐1, and accelerations from ?0.1 m s^‐2 to +0.1 m s^‐2 at a step of 0.02 m s^‐2. Furthermore, an 8 × 8 two‐dimensional coordinates system with 16 groups of TENGs is created, and the moving path of an object is obtained. This study opens up a new area of TENGs as active sensors with great potential in self‐powered systems, positioning detecting, motion tracking, environmental and infrastructure monitoring, and security.     

Electrochemical Cathodic Protection Powered by Triboelectric Nanogenerator

Metal corrosion is universal in the nature and the corrosion prevention for metals plays an important role everywhere in national economic development and daily life. Here a disk triboelectric nanogenerator (TENG) with segmental structures is introduced as power source to achieve a special cathodic protection effect for steels. The output transferred charges and short‐circuit current density of the TENG achieve 1.41 mC/min and 10.1 mA/m², respectively, when the rotating speed is 1000 revolutions per minute (rpm). The cathodic protection potential, Tafel polarization curves and electrochemical impedance spectra (EIS) measurements are measured to evaluate the corrosion protection effect for the 403 stainless steel (403SS). The cathodic protection potential range from –320 mV to –5320 mV is achieved by changing rotation speeds and external resistance when the steel is coupled in a 0.5 m NaCl solution to the negative pole of the disk TENG. The corrosion tests results indicate that the TENG can produce 59.1% degree of protection for Q235 steels in 0.5 m NaCl solution. Furthermore, an application of marine corrosion prevention is presented by mounting the TENG onto a buoy. This work demonstrates a versatile, cost‐effect and self‐powered system to scavenging mechanical energy from environment, leading to effectively protect the metal corrosion without additional power sources.     

Self‐Recovering Triboelectric Nanogenerator as Active Multifunctional Sensors

A novel self‐recovering triboelectric nanogenerator (STENG) driven by airflow is designed as active multifunctional sensors. A spring is assembled into the STENG and enables the nanogenerator to have self‐recovering characteristic. The maximum output voltage and current of the STENG is about 251 V and 56 μA, respectively, corresponding to an output power of 3.1 mW. The STENG can act as an active multifunctional sensors that includes a humidity sensor, airflow rate sensor, and motion sensor. The STENG‐based humidity sensor has a wide detection range of 20%–100%, rapid response time of 18 ms, and recovery time of 80 ms. Besides, the STENG could be utilized in the application of security monitoring. This work expands practical applications of triboelectric nanogenerators as active sensors with advantages of simple fabrication and low cost.     

Rolling Friction Enhanced Free‐Standing Triboelectric Nanogenerators and their Applications in Self‐Powered Electrochemical Recovery Systems

Heavy metals contained in wastewater are one of the most serious pollutions in natural resources. A self‐powered electrochemical recovery system for collecting Cu ions in wastewater by incorporating a rolling friction enhanced freestanding triboelectric nanogenerator (RF‐TENG) is developed here. The RF‐TENG utilizes integrated cylindrical surfaces using the conjunction of rolling electrification and freestanding electrostatic induction, which shows outstanding output performance and ultrarobust stability. By using the kinetic energy of flowing water, a collection efficiency of up to 80% for Cu²⁺ ions in wastewater has been achieved. Self‐powered electrochemical systems are one of the most promising applications of TENGs for independent and sustainable driving of electrochemical reactions without the need for any additional power supply. This research is a substantial advancement towards the practical applications of triboelectric nanogenerators and self‐powered electrochemical systems.     

Self‐Healing,Flexible, and Tailorable Triboelectric Nanogenerators for Self‐Powered Sensors based on Thermal Effect of Infrared Radiation

Self‐healing triboelectric nanogenerators (TENGs) with flexibility, robustness, and conformability are highly desirable for promising flexible and wearable devices, which can serve as a durable, stable, and renewable power supply, as well as a self‐powered sensor. Herein, an entirely self‐healing, flexible, and tailorable TENG is designed as a wearable sensor to monitor human motion, with infrared radiation from skin to promote self‐healing after being broken based on thermal effect of infrared radiation. Human skin is a natural infrared radiation emitter, providing favorable conditions for the device to function efficiently. The reversible imine bonds and quadruple hydrogen bonding (UPy) moieties are introduced into polymer networks to construct self‐healable electrification layer. UPy‐functionalized multiwalled carbon nanotubes are further incorporated into healable polymer to obtain conductive nanocomposite. Driven by the dynamic bonds, the designed and synthesized materials show excellent intrinsic self‐healing and shape‐tailorable features. Moreover, there is a robust interface bonding in the TENG devices due to the similar healable networks between electrification layer and electrode. The output electric performances of the self‐healable TENG devices can almost restore their original state when the damage of the devices occurs. This work presents a novel strategy for flexible devices, contributing to future sustainable energy and wearable electronics.     

Cellulose II Aerogel‐Based Triboelectric Nanogenerator

Cellulose‐based triboelectric nanogenerators (TENGs) have gained increasing attention. In this study, a novel method is demonstrated to synthesize cellulose‐based aerogels and such aerogels are used to fabricate TENGs that can serve as mechanical energy harvesters and self‐powered sensors. The cellulose II aerogel is fabricated via a dissolution–regeneration process in a green inorganic molten salt hydrate solvent (lithium bromide trihydrate), where. The as‐fabricated cellulose II aerogel exhibits an interconnected open‐pore 3D network structure, higher degree of flexibility, high porosity, and a high surface area of 221.3 m² g^?1. Given its architectural merits, the cellulose II aerogel‐based TENG presents an excellent mechanical response sensitivity and high electrical output performance. By blending with other natural polysaccharides, i.e., chitosan and alginic acid, electron‐donating and electron‐withdrawing groups are introduced into the composite cellulose II aerogels, which significantly improves the triboelectric performance of the TENG. The cellulose II aerogel‐based TENG is demonstrated to light up light‐emitting diodes, charge commercial capacitors, power a calculator, and monitor human motions. This study demonstrates the facile fabrication of cellulose II aerogel and its application in TENG, which leads to a high‐performance and eco‐friendly energy harvesting and self‐powered system.     

Bioinspired Triboelectric Nanogenerators as Self‐Powered Electronic Skin for Robotic Tactile Sensing

Electronic skin (e‐skin) has been under the spotlight due to great potential for applications in robotics, human–machine interfaces, and healthcare. Meanwhile, triboelectric nanogenerators (TENGs) have been emerging as an effective approach to realize self‐powered e‐skin sensors. In this work, bioinspired TENGs as self‐powered e‐skin sensors are developed and their applications for robotic tactile sensing are also demonstrated. Through the facile replication of the surface morphology of natural plants, the interlocking microstructures are generated on tribo‐layers to enhance triboelectric effects. Along with the adoption of polytetrafluoroethylene (PTFE) tinny burrs on the microstructured tribo‐surface, the sensitivity for pressure measurement is boosted with a 14‐fold increase. The tactile sensing capability of the TENG e‐skin sensors are demonstrated through the characterizations of handshaking pressure and bending angles of each finger of a bionic hand during handshaking with human. The TENG e‐skin sensors can also be utilized for tactile object recognition to measure surface roughness and discern hardness. The facile fabrication scheme of the self‐powered TENG e‐skin sensors enables their great potential for applications in robotic dexterous manipulation, prosthetics, human–machine interfaces, etc.     

Single‐Thread‐Based Wearable and Highly Stretchable Triboelectric Nanogenerators and Their Applications in Cloth‐Based Self‐Powered Human‐Interactive and Biomedical Sensing

The development of wearable and large‐area fabric energy harvester and sensor has received great attention due to their promising applications in next‐generation autonomous and wearable healthcare technologies. Here, a new type of “single” thread‐based triboelectric nanogenerator (TENG) and its uses in elastically textile‐based energy harvesting and sensing have been demonstrated. The energy‐harvesting thread composed by one silicone‐rubber‐coated stainless‐steel thread can extract energy during contact with skin. With sewing the energy‐harvesting thread into a serpentine shape on an elastic textile, a highly stretchable and scalable TENG textile is realized to scavenge various kinds of human‐motion energy. The collected energy is capable to sustainably power a commercial smart watch. Moreover, the simplified single triboelectric thread can be applied in a wide range of thread‐based self‐powered and active sensing uses, including gesture sensing, human‐interactive interfaces, and human physiological signal monitoring. After integration with microcontrollers, more complicated systems, such as wireless wearable keyboards and smart beds, are demonstrated. These results show that the newly designed single‐thread‐based TENG, with the advantage of interactive, responsive, sewable, and conformal features, can meet application needs of a vast variety of fields, ranging from wearable and stretchable energy harvesters to smart cloth‐based articles.     

A Highly Stretchable Fiber‐Based Triboelectric Nanogenerator for Self‐Powered Wearable Electronics

The development of flexible and stretchable electronics has attracted intensive attention for their promising applications in next‐generation wearable functional devices. However, these stretchable devices that are made in a conventional planar format have largely hindered their development, especially in highly stretchable conditions. Herein, a novel type of highly stretchable, fiber‐based triboelectric nanogenerator (fiber‐like TENG) for power generation is developed. Owing to the advanced structural designs, including the fiber‐convolving fiber and the stretchable electrodes on elastic silicone rubber fiber, the fiber‐like TENG can be operated at stretching mode with high strains up to 70% and is demonstrated for a broad range of applications such as powering a commercial capacitor, LCD screen, digital watch/calculator, and self‐powered acceleration sensor. This work verifies the promising potential of a novel fiber‐based structure for both power generation and self‐powered sensing.     

A Motion Vector Sensor via Direct‐Current Triboelectric Nanogenerator

Motion vector sensors play an important role in artificial intelligence and internet of things. Here, a triboelectric vector sensor (TVS) based on a direct‐current triboelectric nanogenerator is reported, for self‐powered measuring various motion parameters, including displacement, velocity, acceleration, angular, and angular velocity. Based on the working mechanism of the contact‐electrification effect and electrostatic breakdown, a continuous DC signal can be collected to directly monitor moving objects free from environmental electromagnetic signal interference existing in conventional self‐powered TVSs with an alternative‐current signal output, which not only enhances the sensitivity of sensors, but also provides a simple solution to miniaturize the sensors. Its sensitivity is demonstrated to be equivalent to state‐of‐the‐art photoelectric technology by a comparative experiment in an intelligent mouse. Notably, an intelligent pen based on the miniaturized TVS is designed to realize motion trajectory tracing, mapping, and writing on the curved surface. This work provides a new paradigm shift to design motion vector sensors and self‐powered sensors in artificial intelligent and internet of things.     

Waterproof,Breathable, and Antibacterial Self‐Powered e‐Textiles Based on Omniphobic Triboelectric Nanogenerators

Multifunctional electronic textiles (e‐textiles) incorporating miniaturized electronic devices will pave the way toward a new generation of wearable devices and human–machine interfaces. Unfortunately, the development of e‐textiles is subject to critical challenges, such as battery dependence, breathability, satisfactory washability, and compatibility with mass production techniques. This work describes a simple and cost‐effective method to transform conventional garments and textiles into waterproof, breathable, and antibacterial e‐textiles for self‐powered human–machine interfacing. Combining embroidery with the spray‐based deposition of fluoroalkylated organosilanes and highly networked nanoflakes, omniphobic triboelectric nanogenerators (R^F‐TENGs) can be incorporated into any fiber‐based textile to power wearable devices using energy harvested from human motion. R^F‐TENGs are thin, flexible, breathable (air permeability 90.5 mm s^?1), inexpensive to fabricate (<0.04$ cm^?2), and capable of producing a high power density (600 µW cm^?2). E‐textiles based on R^F‐TENGs repel water, stains, and bacterial growth, and show excellent stability under mechanical deformations and remarkable washing durability under standard machine‐washing tests. Moreover, e‐textiles based on R^F‐TENGs are compatible with large‐scale production processes and exhibit high sensitivity to touch, enabling the cost‐effective manufacturing of wearable human–machine interfaces.     

Self‐Powered Electrochemical Synthesis of Polypyrrole from the Pulsed Output of a Triboelectric Nanogenerator as a Sustainable Energy System

Triboelectric nanogenerators (TENG) are able to convert mechanical energy into electricity. In this work, a self‐powered electrochemical synthesis circle is designed, in which the electrode material of the TENG, polypyrrole (PPy), is prepared by the pulse output of the PPy‐based TENG itself. The TENG based on PPy from self‐powered synthesis (SPSPPy) presents a competitive performance compared to those made from commercial pulse sources. A supercapacitor that is fabricated from SPSPPy has a far superior performance than that synthesized by the conventional galvanostatic method. Furthermore, a self‐charging power system that integrates a TENG and a supercapacitor is demonstrated to drive an electronic device sustainably. Moreover, the polymerization efficiency is optimized in TENG‐based electrochemical synthesis because its high voltage can sustain multiple reactors simultaneously. Its upper limit is theoretically analyzed for optimal energy utility, and a maximum number of 39 reactors can be powered experimentally. Hence, TENG is validated as an effective pulse generator for the synthesis of PPy as well as other electrochemical technology, and this work greatly improves the understandings of TENG‐based self‐powered electrochemical systems.     

Self‐Powered Trajectory,Velocity, and Acceleration Tracking of a Moving Object/Body using a Triboelectric Sensor

Motion tracking is of great importance in a wide range of fields such as automation, robotics, security, sports and entertainment. Here, a self‐powered, single‐electrode‐based triboelectric sensor (TES) is reported to accurately detect the movement of a moving object/body in two dimensions. Based on the coupling of triboelectric effect and electrostatic induction, the movement of an object on the top surface of a polytetrafluoroethylene (PTFE) layer induces changes in the electrical potential of the patterned aluminum electrodes underneath. From the measurements of the output performance (open‐circuit voltage and short‐circuit current), the motion information about the object, such as trajectory, velocity, and acceleration is derived in conformity with the preset values. Moreover, the TES can detect motions of more than one objects moving at the same time. In addition, applications of the TES are demonstrated by using LED illuminations as real‐time indicators to visualize the movement of a sliding object and the walking steps of a person.