3D Orthogonal Woven Triboelectric Nanogenerator for Effective Biomechanical Energy Harvesting and as Self‐Powered Active Motion Sensors

The development of wearable and large‐area energy‐harvesting textiles has received intensive attention due to their promising applications in next‐generation wearable functional electronics. However, the limited power outputs of conventional textiles have largely hindered their development. Here, in combination with the stainless steel/polyester fiber blended yarn, the polydimethylsiloxane‐coated energy‐harvesting yarn, and nonconductive binding yarn, a high‐power‐output textile triboelectric nanogenerator (TENG) with 3D orthogonal woven structure is developed for effective biomechanical energy harvesting and active motion signal tracking. Based on the advanced 3D structural design, the maximum peak power density of 3D textile can reach 263.36 mW m^?2 under the tapping frequency of 3 Hz, which is several times more than that of conventional 2D textile TENGs. Besides, its collected power is capable of lighting up a warning indicator, sustainably charging a commercial capacitor, and powering a smart watch. The 3D textile TENG can also be used as a self‐powered active motion sensor to constantly monitor the movement signals of human body. Furthermore, a smart dancing blanket is designed to simultaneously convert biomechanical energy and perceive body movement. This work provides a new direction for multifunctional self‐powered textiles with potential applications in wearable electronics, home security, and personalized healthcare.     

A Bistable Triboelectric Nanogenerator for Low-Grade Thermal Energy Harvesting and Solar Thermal Energy Conversion

Converting ubiquitous ambient low-grade thermal energy into electricity is of great significance for tackling the fossil energy shortage and environmental crisis but poses a considerable challenge. Here, a novel thermal-driven triboelectric nanogenerator (TD-TENG) is developed, which utilizes a bimetallic beam with a bi-stable dynamic feature to induce continuous mechanical oscillations, and the mechanical motion is then converted into electric power using a contact-separation TENG. The thermal process inside the device is systematically investigated and effective thermal management is conducted accordingly. After optimization, the TD-TENG can produce a power density of 323.9 mW m⁻² at 59.5 °C, obtaining the highest record of TENG-based thermal energy harvesters. Besides, the first prototype of TENG-based solar thermal harvester is successfully demonstrated, with a power density of 364.4 mW m⁻². Moreover, the TD-TENG can harvest and dissipate the heat at the same time, exhibiting great potential in over-heated electronics protection as well as architectural energy conservation. Most importantly, the operation temperature range of the TD-TENG is tunable by adjusting the bimetal parameters, allowing the device a wide and flexible working thermal gradient. These unique properties validate the TD-TENG is a simple, feasible, cost-effective, and high-efficient low-grade thermal energy harvester.     

Interfacial Roughness Enhanced Gel/Elastomer Interfacial Bonding Enables Robust and Stretchable Triboelectric Nanogenerator for Reliable Energy Harvesting

Gel-based triboelectric nanogenerator (TENG) has demonstrated promising potentials in stretchable electronics owing to gel electrodes’ intrinsic softness, stretchability, and conductivity. However, delamination between gel and elastomer layers in deformations remains a considerable challenge for gel-based TENG, which most often induces structure failure. Herein, gels are regarded as adhesives and further effectively enhances interfacial bonding strength by a rough interface in adhesives’ view, which exploits gels’ liquid-to-solid transformation. This method just needs surface roughness of elastomer, which avoids chemical modification. Moreover, this method is effective to both organogel with good stickiness and hydrogel with weak stickiness, demonstrating wide applicability to different gels. Owing to the tough gel/elastomer interfacial bonding, TENG-Rough largely solves delamination problem under various deformations and the corresponding output performances of TENG-Rough are also maintained, implying a robust stretchable TENG device for reliable energy harvesting. This work demonstrates a general and facile method to enhance interfacial bonding in an adhesives’ way, which provides a view for addressing delamination problem in gel-based TENGs and other kinds of gel-based devices.     

Thermal-Driven Soft-Contact Triboelectric Nanogenerator for Energy Harvesting and Industrial Cooling Water Monitoring

In this paper, a quaternary dielectric soft-contact rotary triboelectric nanogenerator (QDSR-TENG) of low frictional resistance is fabricated for combining TENG with a shape memory alloy (SMA) engine. The introduction of rabbit fur brush and FEP brush results in charge pumps with a partially soft contact structure. Benefiting from the low friction loss of the structure, the QDSR-TENG can operate stably and continually for 100k cycles without significant output degradation. The SMA engine exhibits thermally induced phase transformation and super-elasticity and can be utilized for harnessing waste heat energy. The thermal-driven QDSR-TENG can operate with a water source of 43 °C with a distinguishable response to the variation of temperatures. Such a low starting temperature not only promotes the harvesting of low-grade thermal energy, but also results in a self-monitoring industrial cooling water system. The coupled elastocaloric power and cooling cycle proposed in the thermal-driven QDSR-TENG opens a new paradigm for the application in energy harvesting and smart sensing.     

A Self-Powered Dielectrophoretic Microparticle Manipulation Platform Based on a Triboelectric Nanogenerator

Lab-on-a-chip systems aim to integrate laboratory operations on a miniaturized device with broad application prospects in the field of point-of-care testing. However, bulky peripheral power resources, such as high-voltage supplies, function generators, and amplifiers, hamper the commercialization of the system. In this work, a portable, self-powered microparticle manipulation platform based on triboelectrically driven dielectrophoresis (DEP) is reported. A rotary freestanding triboelectric nanogenerator (RF-TENG) and rectifier/filter circuit supply a high-voltage direct-current signal to form a non-uniform electric field within the microchannel, realizing controllable actuation of the microparticles through DEP. The operating mechanism of this platform and the control performance of the moving particles are systematically studied and analyzed. Randomly distributed particles converge in a row after passing through the serpentine channel and various particles are separated owing to the different DEP forces. Ultimately, the high-efficiency separation of live and dead yeast cells is achieved using this platform. RF-TENG as the power source for lab-on-a-chip exhibits better safety and portability than traditional high-voltage power sources. This study presents a promising solution for the commercialization of lab-on-a-chip.     

Energy Harvesting Using Wastepaper-Based Triboelectric Nanogenerators

Inks and toners used for printing contain materials, such as polyester, with strong triboelectric properties to enhance the binding effects, making wastepaper, such as magazines and newspapers, good candidates for triboelectric materials. Herein, high-output power triboelectric nanogenerators (TENGs) that utilize wastepaper as triboelectric layers (wastepaper-based triboelectric nanogenerators (WP–TENGs)) are reported. Journal paper and office copy paper wastes are investigated. The results show that the maximum power densities of the WP–TENGs reach 43.5 W m⁻², which is approximately 250 times the previously reported output of the TENG with a recycled triboelectric layer made from wastepaper. The maximum open circuit voltage (V _OC) and short circuit current (I _SC) are 774 V and 3.92 mA (784 mA m⁻²), respectively. These findings can be applied to extend the life cycle of printed papers for energy harvesting, and they can later be applied for materials recycling to enhance the sustainable development of our society.     

Highly Transparent,Stretchable, and Self‐Healing Ionic‐Skin Triboelectric Nanogenerators for Energy Harvesting and Touch Applications

Recently developed triboelectric nanogenerators (TENGs) act as a promising power source for self‐powered electronic devices. However, the majority of TENGs are fabricated using metallic electrodes and cannot achieve high stretchability and transparency, simultaneously. Here, slime‐based ionic conductors are used as transparent current‐collecting layers of TENG, thus significantly enhancing their energy generation, stretchability, transparency, and instilling self‐healing characteristics. This is the first demonstration of using an ionic conductor as the current collector in a mechanical energy harvester. The resulting ionic‐skin TENG (IS‐TENG) has a transparency of 92% transmittance, and its energy‐harvesting performance is 12 times higher than that of the silver‐based electronic current collectors. In addition, they are capable of enduring a uniaxial strain up to 700%, giving the highest performance compared to all other transparent and stretchable mechanical‐energy harvesters. Additionally, this is the first demonstration of an autonomously self‐healing TENG that can recover its performance even after 300 times of complete bifurcation. The IS‐TENG represents the first prototype of a highly deformable and transparent power source that is able to autonomously self‐heal quickly and repeatedly at room temperature, and thus can be used as a power supply for digital watches, touch sensors, artificial intelligence, and biointegrated electronics.     

Hierarchical Honeycomb-Structured Electret/Triboelectric Nanogenerator for Biomechanical and Morphing Wing Energy Harvesting

Flexible, compact, lightweight and sustainable power sources are indispensable for modern wearable and personal electron-ics and small-unmanned aerial vehicles ...     

Inductor‐Free Wireless Energy Delivery via Maxwell's Displacement Current from an Electrodeless Triboelectric Nanogenerator

Wireless power delivery has been a dream technology for applications in medical science, security, radio frequency identification (RFID), and the internet of things, and is usually based on induction coils and/or antenna. Here, a new approach is demonstrated for wireless power delivery by using the Maxwell's displacement current generated by an electrodeless triboelectric nanogenerator (TENG) that directly harvests ambient mechanical energy. A rotary electrodeless TENG is fabricated using the contact and sliding mode with a segmented structure. Due to the leakage of electric field between the segments during relative rotation, the generated Maxwell's displacement current in free space is collected by metal collectors. At a gap distance of 3 cm, the output wireless current density and voltage can reach 7 µA cm⁻² and 65 V, respectively. A larger rotary electrodeless TENG and flexible wearable electrodeless TENG are demonstrated to power light‐emitting diodes (LEDs) through wireless energy delivery. This innovative discovery opens a new avenue for noncontact, wireless energy transmission for applications in portable and wearable electronics.     

Fiber/Fabric-Based Piezoelectric and Triboelectric Nanogenerators for Flexible/Stretchable and Wearable Electronics and Artificial Intelligence

Integration of advanced nanogenerator technology with conventional textile processes fosters the emergence of textile-based nanogenerators (NGs), which will inevitably promote the rapid development and widespread applications of next-generation wearable electronics and multifaceted artificial intelligence systems. NGs endow smart textiles with mechanical energy harvesting and multifunctional self-powered sensing capabilities, while textiles provide a versatile flexible design carrier and extensive wearable application platform for their development. However, due to the lack of an effective interactive platform and communication channel between researchers specializing in NGs and those good at textiles, it is rather difficult to achieve fiber/fabric-based NGs with both excellent electrical output properties and outstanding textile-related performances. To this end, a critical review is presented on the current state of the arts of wearable fiber/fabric-based piezoelectric nanogenerators and triboelectric nanogenerators with respect to basic classifications, material selections, fabrication techniques, structural designs, and working principles, as well as potential applications. Furthermore, the potential difficulties and tough challenges that can impede their large-scale commercial applications are summarized and discussed. It is hoped that this review will not only deepen the ties between smart textiles and wearable NGs, but also push forward further research and applications of future wearable fiber/fabric-based NGs.     

Electrospinning Triboelectric Laminates: A Pathway for Scaling Energy Harvesters

Herein, a new paradigm of triboelectric polymers—the triboelectric laminate—a volumetric material with electromechanical response comparable to the benchmark soft piezoelectric material polyvinylidene difluoride is reported. The electromechanical response in the triboelectric laminate arises from aligned dipoles, generated from the orientation of contact electrification in the laminates bulk volume. The dipoles form between sequential bilayers consisting of two different electrospun polymer fibers of different diameter. The loose interface between the fiber bilayers ensures friction and triboelectric charging between two polymers. The electric output from the electrospun triboelectric laminate increases with increasing density of the bilayers. This system design has clear benefits over other flexible devices for mechanical energy harvesting as it does not require any poling procedures, and the electromechanical response is stable over 24 h of continuous operation. Moreover, the electromechanically responsive electrospun laminate can be made from all types of polymers, thus providing ample room for further improvements or functionalities such as stretchability, biodegradability, or biocompatibility. The concept of a triboelectric laminate can be introduced into existing triboelectric nanogenerator form factors, to dramatically increase charge harvesting of a variety of devices.     

Natural and Eco-Friendly Materials for Triboelectric Energy Harvesting

Triboelectric nanogenerators(TENGs)are promising electric energy harvesting devices as they can produce renewable clean energy using mechanical excitations from the environment.Several designs of triboelectric energy harvesters relying on biocompatible and eco-friendly natural materials have been introduced in recent years.Their ability to provide customizable self-powering for a wide range of applications,including biomedical devices,pressure and chemical sensors,and battery charging appliances,has been demonstrated.This review summarizes major advances already achieved in the field of triboelectric energy harvesting using biocompatible and eco-friendly natural materials.A rigorous,comparative,and critical analysis of preparation and testing methods is also presented.Electric power up to 14 mW was already achieved for the dry leaf/polyvinylidene fluoride-based TENG devices.These findings highlight the potential of eco-friendly self-powering systems and demonstrate the unique properties of the plants to generate electric energy for multiple applications.     

Signal Output of Triboelectric Nanogenerator at Oil–Water–Solid Multiphase Interfaces and its Application for Dual‐Signal Chemical Sensing

A liquid–solid contact triboelectric nanogenerator (TENG) based on poly(tetrafluoroethylene) (PTFE) film, a copper electrode, and a glass substrate for harvesting energy in oil/water multiphases is reported. There are two distinctive signals being generated, one is from the contact electrification and electrostatic induction between the liquid (water/oil) and the PTFE film (V_TENG and I_TENG); and the other is from the electrostatic induction in the copper electrode by the oil/water interfacial charges (ΔV_interface and I_interface), which is generated only when the liquid–solid contact TENG is inserted across the oil/water interface. The two signals show interesting opposite changing trends that the V_TENG and I_TENG decrease while the oil/water interfacial signals of ΔV_interface and I_interface increase after coating a layer of polydopamine on the surfaces of PTFE and glass via self‐polymerization. As an application of the observed phenomena, both the values of I_TENG and I_interface have a good linear relationship versus the natural logarithm of the concentration of the dopamine. Based on this, the first self‐powered dual‐signal detection of dopamine using TENG is demonstrated.     

On‐Skin Triboelectric Nanogenerator and Self‐Powered Sensor with Ultrathin Thickness and High Stretchability

Researchers have devoted a lot of efforts on pursuing light weight and high flexibility for the wearable electronics, which also requires the related energy harvesting devices to have ultrathin thickness and high stretchability. Hence, an elastic triboelectric nanogenerator (TENG) is proposed that can serve as the second skin on human body. The total thickness of this TENG is about 102 µm and the device can work durably under a strain of 100%. The carbon grease is painted on the surface of elastomer film to work as stretchable electrode and thus the fine geometry control of the electrode can be achieved. This elastic TENG can even work on the human fingers without disturbing body movement. The open‐circuit voltage and short‐circuit current from the device with a contact area of 9 cm² can reach 115 V and 3 µA, respectively. Two kinds of self‐powered sensor systems with optimized identification strategies are also designed to demonstrate the application possibility of this elastic TENG. The superior characteristics of ultrathin thickness, high stretchability, and fine geometry control of this TENG can promote many potential applications in the field of wearable self‐powered sensory system, electronics skin, artificial muscles, and soft robotics.