Search

As wearable devices continue to be updated and iterated, there is an increasing demand for energy supplies that are small, portable and capable of working continuously for extended periods of time. Here, a hybrid triboelectric-electromagnetic nanogenerator (HNG) based on a biomechanical energy harvester is demonstrated. The HNG is designed to be worn on the wrist according to the curve of the wearer’s arm swing. During the swinging of the arm, the magnet covered by the PTFE film will move relative to the curved cavity of the HNG and take on a negative charge by rubbing against the inner wall of the Cu coated cavity, resulting in a change in the potential difference between the two copper electrodes on the inner wall of the curved cavity. The movement of the magnet causes the magnetic flux of the three pairs of coils on both sides of the arc track to change to produce the induced electric potential, which converts the mechanical energy generated by the arm swing into electrical energy. After the rational design, the HNG is integrated into a small size device to achieve the collection of biomechanical energy. Several experiments were conducted to verify the HNG’s usability. Experiments show that the HNG takes 90 s to charge from 0 V to 1.2 V for a 1000 μF capacitor. In addition, the HNG can light up 23 LEDs simultaneously and provide a continuous supply of energy to portable electronic devices, such as temperature sensors and electronic watches after the capacitor has stored the energy. Furthermore, the HNG is experimentally verified by volunteers wearing the HNG to achieve continuous and stable output in all three states of slow swing, fast swing and running swing. This work not only provides a useful reference for human biomechanical energy harvesting, but can also provide a continuous, clean source of energy for wearable devices.

Self-powered technology is a novel power supply technology. In recent years, self-powered intelligent products have attracted much interests. Triboelectric nanogenerators (TENGs) can convert mechanical energy into electrical energy by contact and relative motion, thus providing the possibility of self-powering for electronic equipments. However, TENG-based self-powered technologies are limited by low power output and poor conversion efficiency. In this review, we present the development of TENG-based self-powered systems, with the emphasis on the output power of TENG and how to improve it. Based on the above applications, we propose the idea of TENG-driven self-powered remote robots, providing promising scenarios of small remote robots for land rescue or underwater detection. Due to the limited power output of the current TENGs, there are still some difficulties in driving the robot. Aiming at the problems of low power supply and poor conversion efficiency, we introduce the current attempts to improve the power generation efficiency from the perspectives of mechanical structure, electrode materials and auxiliary tools. We also outline the applications of TENGs as power supply systems in various fields such as sensing, wearable devices, and collecting Marine energy. Finally, we forecast the development prospect of TENG.

An intelligent monitoring lubricant is essential for the development of smart machines because unexpected and fatal failures of critical dynamic components in the machines happen every day, threatening the life and health of humans. Inspired by the triboelectric nanogenerators (TENGs) work on water, we present a feasible way to prepare a self-powered triboelectric sensor for real-time monitoring of lubricating oils via the contact electrification process of oil–solid contact (O–S TENG). Typical intruding contaminants in pure base oils can be successfully monitored. The O–S TENG has very good sensitivity, which even can respectively detect at least 1 mg mL–1 debris and 0.01 wt % water contaminants. Furthermore, the real-time monitoring of formulated engine lubricating oil in a real engine oil tank is achieved. Our results show that electron transfer is possible from an oil to solid surface during contact electrification. The electrical output characteristic depends on the screen effect from such as wear debris, deposited carbons, and age-induced organic molecules in oils. Previous work only qualitatively identified that the output ability of liquid can be improved by leaving less liquid adsorbed on the TENG surface, but the adsorption mass and adsorption speed of liquid and its consequences for the output performance were not studied. We quantitatively study the internal relationship between output ability and adsorbing behavior of lubricating oils by quartz crystal microbalance with dissipation (QCM-D) for liquid–solid contact interfaces. This study provides a real-time, online, self-powered strategy for intelligent diagnosis of lubricating oils.

The growing demand for energy and environmental concern are crucial driving forces for the development of green and sustainable energy. The triboelectric nanogenerator (TENG) has emerged as a promising solution for harvesting mechanical energy from the environment. In this research, a natural rubber (NR)-based TENG has been developed with an enhanced power output from the incorporation of cellulose nanofibers (CNF) and activated carbon (AC) nanoparticles. The highest voltage output of 137 V, a current of 12.1 µA, and power density of 2.74 W/m2 were achieved from the fabricated NR–CNF–AC TENG. This is attributed to the synergistic effect of the electron-donating properties of cellulose material and the large specific surface area of AC materials. The enhancement of TENG performance paves the way for the application of natural-based materials to convert mechanical energy into electricity, as a clean and sustainable energy source.

The hydroxyl groups on the cellulose macromolecular chain cause the cellulose surface to have strong reactivity. In this study, 1H, 1H, 2H, 2H-perfluorodecyltriethoxysilane (PDOTES) was used to modify cellulose to improve its triboelectric properties, and a triboelectric nanogenerator (TENG) was assembled. The introduction of fluorine groups reduced the surface potential of cellulose and turned it into a negative phase, which enhanced the ability to capture electrons. The electrical properties increased by 30% compared with unmodified cellulose. According to the principles of TENGs, a self-powered human-wearable device was designed using PDOTES-paper, which could detect movements of the human body, such as walking and running, and facilitated a practical method for the preparation of efficient wearable sensors.

Triboelectric nanogenerators (TENGs) have attracted many researchers’ attention with their remarkable potential despite the fact that the practical implementation requires further improvement in their electric performance. In this work, a novel graphene phase two-dimension material, graphitic carbon nitride (g-C3N4), was employed for the development of a TENG material with enhanced features. An electrospun nanofibrous PA66 membrane doped with g-C3N4 was fabricated as a multifunctional TENG for harvesting different kinds of mechanical energy and detecting human motions. By utilizing the innovative 2D material in PA66 solution for electrospinning, the as-made TENG showed a two times enhancement in electrical performance as compared to the control device, and also had the advantages of lightweight, softness, high porosity, and rugged interface properties. The assembled TENG with 4 cm2 could light up 40 light-emitting diodes by gentle hand clapping and power electronic watches or calculators with charging capacitors. At a given impact force of 40 N and 3 Hz, the as-made TENG can generate an open-circuit voltage of 80 V, short current of ±3 µA, charge transfer of 50 nC, and a maximum power density of 45 mW/m2 at a load resistance of 500 MΩ. The UV light sensitivity of TENG was also improved via g-C3N4 doping, showing that charge transfer is very sensitive with a two times enhancement with dopant. For the demonstration of applications, the g-C3N4 doped TENG was fabricated into an energy flag to scavenge wind energy and sensor devices for detecting human motions.

Wave energy has the potential to become a large source of renewable energy, but there is no consensus on the most efficient mode of extracting power. One major component of all wave energy converters (WECs) is the power take off (PTO) mechanism, which converts the absorbed energy of the system to useful power. Triboelectric nanogenerators (TENGs) generate electricity through friction of two dissimilar materials, and previous studies have shown potential for this technology to be used as a PTO mechanism. This study tested different models of a horizontal-axis hydro turbine in order to evaluate the performance of a rotational TENG in the ocean environment. The hydro turbine models were tested in the tow tank to observe how much rotation can be produced by incoming waves and how each model parameter impacted the performance or rotational speed. The conclusions drawn from the experiment were used to determine how a similar model could be realistically implemented on unmanned undersea vehicles (UUVs). The number of blades on the hydro turbine most significantly impacted performance, and single blade models had the highest average angular speed compared to any other model. Outstanding Thesis Ensign, United States Navy Approved for public release. Distribution is unlimited.

Vibration sensing is of great significance in offshore engineering monitoring and safety detection. This paper presented a low-frequency vibration sensor (LV-TENG) based on a cantilever-beam-structured triboelectric nanogenerator, which can perform high-precision vibration sensing while conducting vibration energy collection effectively. The LV-TENG was composed of two aluminum electrode layers, a spring steel sheet covered with polytetrafluoroethylene (PTFE) and a first-order vibration mode structured frame. Under the excitation of external vibration, the spring steel sheet undergoes first-order modal vibrations between the aluminum electrodes and generates a periodically fluctuating electrical signal in the external circuit. The vibration profile of the cantilever beam was first analyzed theoretically to provide guidance for structural design. On this basis, the influence of the main structural parameters, including the structure of the Al electrode, the thickness of the steel plate, and the electronegative materials, on the output performance of LV-TENG was experimentally investigated and the structure was optimized to enhance electrical output. The results showed that the LV-TENG can accurately sense structure vibration with a frequency of 0.1 Hz to 5.0 Hz and an amplitude of 2.0 mm to 10.0 mm. The measured output voltage followed a positive linear relationship with frequency and the fitted correlation coefficient reached 0.994. The demonstration experiment indicated that the LV-TENG is expected to provide a new avenue for low-frequency vibration monitoring and can be used for structural health monitoring analysis in marine engineering.

openaire: EC/H2020/788489/EU//BioELCell Funding Information: This work was supported by the National Key Research and Development Program of China ( 2019YFC1905900 ), the National Natural Science Foundation of China ( 31870566 ), the Jinan Innovation Team ( 2021GXRC023 ), and Taishan Scholars Program . OJR and ZD are grateful for the support received from the Canada Excellence Research Chair Program ( CERC-2018-00006 ), the Canada Foundation for Innovation (Project number 38623 ) and the European Research Council (ERC) under the European Union's Horizon 2020 Research and Innovation Program (grant agreement No 788489 ). Publisher Copyright: © 2022 Water waves are viable low-carbon and renewable sources of power that can be optionally combined with triboelectric nanogeneration (TENG). Herein, we report on the synthesis of a TENG device based on green wrinkled paper tribolayers (W-TENG) assembled in grids (G-TENG) with channels that enable contact-separation modes involving metal balls that roll in phase with the waves. The paper's wrinkle wavelength and amplitude were adjusted by using a crepe blade at a given angle with respect to a drying cylinder, as well as the speed and torque. Polar hierarchical superhydrophobic cellulose micro/nanostructures, proposed as positive tribolayers with enhanced contact area and triboelectric density. The negative (biodegradable) tribolayers were prepared by electrospinning aqueous suspensions of polyvinyl alcohol and poly (ethylene oxide) reinforced with cellulose nanofibers. The charge transfer by the W-TENG reached up to 40 nC in air and retained 27 nC under 85 % relative humidity, ~5 and 7 times higher than those measured in planar TENG counterparts. A G-TENG array charging time (100-μF capacitor) of ~188 s was measured when the voltage of the capacitor raised to ~1.5 V. Overall, we introduce a new, scalable TENG system that is demonstrated for its remarkable ability to harvest blue energy.

Here, we introduce a 2D metal-organic framework (MOF) into the poly(vinylidene fluoride) (PVDF) matrix, which has been comparatively less explored in this field. Highly 2D Ni-MOF has been synthesized in this regard via hydrothermal route and has been incorporated into PVDF matrix via solvent casting technique with ultralow filler (0.5 wt%) loading. The polar phase percentage of 0.5 wt% Ni-MOF loaded PVDF film (NPVDF) has been found to be increased to ~85% from a value of ~55% for neat PVDF. The ultralow filler loading has inhibited the easy breakdown path along with increased dielectric permittivity and hence has enhanced the energy storage performance. On the other hand, significantly enriched polarity and Young’s Modulus has helped in improving its mechanical energy harvesting performance, thereby enhancing the human motion interactive sensing activities. The piezoelectric and piezo-tribo hybrid devices made up of NPVDF film have shown improved output power density of ~3.26 and 31 μW/cm2 compared to those of the piezoelectric and piezo-tribo hybrid devices comprising of neat PVDF (output power density ~0.6 and 17 μW/cm2, respectively). The developed composite can thus be considered an excellent candidate for multifunctional applications.

Triboelectric nanogenerators have attracted extensive attention in energy harvesting due to its light weight, low cost, high flexibility, and diversity of function. However, deterioration in terms of mechanical durability and electrical stability of the triboelectric interface during operation, which are the results of material abrasion, severely limits their practical applications. In this paper, a durable triboelectric nanogenerator inspired by a ball mill was designed by using metal balls in hollow drums as carriers for charge generation and transfer. Composite nanofibers were deposited onto the balls, increasing the triboelectrification with the interdigital electrodes in the inner surface of the drum for higher output and electrostatic repulsion to each other for lower wear. Such a rolling design cannot only increase mechanical durability and maintenance convenience, where the filler can be easily replaced and recycled but also collect wind power with the decreased wearing of materials and sound efficiency in comparison with the typical rotation TENG. In addition, the short circuit current shows a strong linear relationship with the rotation speed in a wide range, which can be used to detect wind speed, thus showing potential applications in distributed energy conversion and self-powered environmental monitoring systems.

The triboelectric nanogenerator (TENG) is a newly developed energy harvesting technology that can convert mechanical energy into electricity. The TENG has received extensive attention due to its potential applications in diverse fields. In this work, a natural based triboelectric material has been developed from a natural rubber (NR) filled with cellulose fiber (CF) and Ag nanoparticles. Ag nanoparticles are incorporated into cellulose fiber (CF@Ag) and are used as a hybrid filler material for the NR composite to enhance the energy conversion efficiency of TENG. The presence of Ag nanoparticles in the NR-CF@Ag composite is found to improve the electrical power output of the TENG by promoting the electron donating ability of the cellulose filler, resulting in the higher positive tribo-polarity of NR. The NR-CF@Ag TENG shows significant improvement in the output power up to five folds compared to the pristine NR TENG. The findings of this work show a great potential for the development of a biodegradable and sustainable power source by converting mechanical energy into electricity.

The development of industry and of the Internet of Things (IoTs) have brought energy issues and huge challenges to the environment. The emergence of triboelectric nanogenerators (TENGs) has attracted wide attention due to their advantages, such as self-powering, lightweight, and facile fabrication. Similarly to paper and other fiber-based materials, which are biocompatible, biodegradable, environmentally friendly, and are everywhere in daily life, paper-based TENGs (P-TENGs) have shown great potential for various energy harvesting and interactive applications. Here, a detailed summary of P-TENGs with two-dimensional patterns and three-dimensional structures is reported. P-TENGs have the potential to be used in many practical applications, including self-powered sensing devices, human–machine interaction, electrochemistry, and highly efficient energy harvesting devices. This leads to a simple yet effective way for the next generation of energy devices and paper electronics.

Acceleration sensors have a wide variety of applications for industrial engineering, biology and navigation. However, passive sensing, narrow detection range, large size, and high manufacturing cost curb their further development. Here, we present a miniaturized acceleration sensor (MAS) with rationally patterned electrodes, based on the single electrode triboelectric mechanism, featuring small size, high accuracy, large detection scale, and environmental friendliness. A stainless-steel ball, as the moving part of the MAS, experiences physical movement that is converted into an electrical signal. Equipped with rationally patterned electrodes, the MAS retains the smallest size and lowest weight compared with the currently reported self-powered acceleration sensors. Benefiting from the voltage-relationship-based direction detection mechanism, eight directions can be identified by one TENG module. Consequently, rotated 22.5° relatively, two TENG modules enable the MAS to detect 16 directions. Moreover, accelerations ranging from 0.1 m/s2 to 50 m/s2 can be identified according to the relationship of response time and accelerations in the horizontal direction. The relationship is obtained through the measurements of the sum of output voltages (VSOC) for the four bottom electrodes with varying accelerations. In addition, no distinct decrease of VSOC is observed after continuously operating for 2000 circles, presenting excellent robustness. Hence, this cost-effective and rationally patterned MAS reveals great potential for human machine interaction, VR/AR (virtual/augmented reality), sports training, and smart city.

Produced by magnetic material dispersed in a viscous environment for the purpose of collecting and converting energy, magnetic rheological compounds greatly strengthen the development of skin-attachable and wearable electrical equipment. Given that magnetic nanomaterial anisotropy has a substantial influence on the interface polarizing of polyvinylidene fluoride (PVDF), it is critical to explore the function of magnetic polymer compounds in the triboelectric layer of triboelectric nanogenerator (TENG) output power. In this study, ferromagnetic cobalt ferrite, CoFe2O4 (CFO), nanoparticles, and PVDF were employed to create a triboelectric composite membrane to improve TENG energy output. The content of β phase in PVDF increased significantly from 51.2% of pure PVDF membrane to 77.7% of 5 wt% CFO nanoparticles in the PVDF matrix, which further increase the dielectric constant and negative charge of the membrane. As a consequence, the energy output of CFO/PVDF-5 TENG increased significantly with a voltage of 17.2 V, a current of 2.27 μA, and a power density of 90.3 mW/m2, which is 2.4 times the performance of pure PVDF TENG. Finally, the proposal for TENG hopes that its extraordinary stability and durability will provide additional views on hydrodynamic power generation in the future.

Triboelectric nanogenerators (TENGs) have proven to be a robust power source for efficiently converting environmental mechanical energy into electricity. Triboelectric technology experienced substantial growth in the past few years, especially in the field of green wearable power sources as the Internet of Things develops. However, it is still difficult to overcome some remaining bottlenecks for wearable TENGs, such as limited choice of materials, unsafe metal electrodes, complex structures, and finally an insufficient electrical output. In this work, we present a simply structured wearable TENG that delivers usable electric power based on human motion. The form of TENG, which combines a friction material of silk and an electrode material of carbon nanotube (CNT) in liquid phase to achieve a biodegradable conductive mixing friction layer is new and unique. A series of delicate investigative experiments were conducted to clarify the impacts of various parameters and their optimal values in the fabrication. Then the special mixing layer was attached to a glove and tested with various daily actions, showing high potential as a power source for wearable electronics and as a motion sensor itself. This new form of CNT-silk TENG will push the field's development toward actual use, with lower cost and less burden for both of production and usage, with the advanced features of high softness, high sensibility, light weight, and simple structure.

Electron propagation in a trapped state between an insulator and a metal during very close contact in a triboelectric nanogenerator (TENG) system was considered in this study. A single energy level (E0) was assumed for the trap and wave function inside the trap, which is related to the ground state energy. The phase of the waveform in the metal (neglecting the rebound effect at the wall) was assumed very small (δ′ ≪ 1) because of the large size of the metal. The contact distance between the trap and metal is very small, which allows us to ignore the vacuum potential. Based on our results, the probability of finding an electron inside the trap as a function of time was found to be in oscillation (i.e., back-and-forth propagation of the electron between the trap and metal leads to an equilibrium state). These results can be used to understand the quantum mechanisms of continuous contact, particularly in sliding-mode TENG systems.

The monitoring data of climbing trajectory and climbing time in rock climbing training are the basis for coaches to select athletes and formulate the next training plans. This article proposes a folding spring triboelectric nanogenerator that can be used for trajectory training and time training in rock climbing training. The folding spring triboelectric nanogenerator, made of PMMA (polymethyl methacrylate), Kapton, PTFE (Polytetrafluoroethylene), Cu (copper) and PLA (polylactic acid), realizes the detection functions based on the voltage pulse generated by the vertical friction between each two adjacent friction layers, and then the width of the output voltage pulse is the training time and the envelope of the space area formed by all the contacted folding spring triboelectric nanogenerator is the climbing trajectory. Test results show that the output voltage amplitude are between 7.5 V and 10.8 V, the output current will drop sharply from 24.5 × 10-7 A when the load resistance exceeds 47k ohms, the time interval between two consecutive uses should be greater than 0.2 s, and the maximum output power is 163.6 × 10-8 W when a 4.7 × 106 ohm load resistance is connected in series, which shows a strong signal-to-noise ratio and anti-interference ability. In addition, the trajectory training and the time training tests results show that the folding spring triboelectric nanogenerator can be used for real-time monitoring in rock climbing training, but it needs to be pressed twice in succession when used for time training limited by the structural and principle.

Owing to its abundance, mechanical energy is a promising ambient energy source. Triboelectric nanogenerators (TENGs) represent an effective mechanical energy harvesting method based on the use of contact electrification. The existing liquid-based TENGs can operate robustly without surface damage; however, the output of these TENGs is considerably smaller than that of solid-based TENGs. Notably, liquid-based TENGs in which the liquid directly contacts the conductive material can produce an electrical current of more than few mA. However, the liquid reservoir must have an adequate volume, and sufficient space must be provided for the liquid to move for generating the electrical output. To ensure a compact and lightweight design and produce electrical output in the low input frequency range, we introduce a mobile stick-type water-based TENG (MSW-TENG). The proposed MSW-TENG can generate an open-circuit voltage and closed-circuit current of up to 710 V and 2.9 mA, respectively, and be utilized as self-powered safety device. The findings of this study can promote the implementation of TENGs in everyday applications.

Recently, tremendous research on small energy supply devices is gaining popularity with the immerging Internet of Things (IoT) technologies. Especially, energy conversion and storage devices can provide opportunities for small electronics. In this research, a micro-nano structured design of electrodes is newly developed for high performing hybrid energy systems with the improved effective surface area. Further, it could be simply fabricated through two-steps synthesis of electrospinning and glass transition of a novel polystyrene (PS) substrate. Herein, the electro-spun nanofiber of polyacrylonitrile (PAN) and Nylon 66 (Nylon) are applied to the dielectric layer of a triboelectric generator (TENG), while the PAN and polyaniline (PANI) composites is utilized as an electroactive material of supercapacitor (SC). As a result, the self-charging power system is successfully integrated with the wrinkled PAN/PS (W-PAN/PS@PANI)-SC and W-TENG by using a rectifier. According to the fabricated hybrid energy systems, the electrical energy produced by W-TENG can be successfully stored into as-fabricated W-PAN/PS@PANI-SC and can also turn on a commercial green LED with the stored energy. Therefore, the micro-nano structured electrode designed for hybrid energy systems can contribute to improve the energy conversion and storage performance of various electronic devices.

The triboelectric nanogenerator (TENG) has emerged as a novel energy technology that converts mechanical energy from surrounding environments to electricity. The TENG fabricated from environmentally friendly materials would encourage the development of next-generation energy technologies that are green and sustainable. In the present work, a green triboelectric material has been fabricated from natural rubber (NR) filled with activated carbon (AC) derived from human hair. It is found that the TENG fabricated from an NR-AC composite as a tribopositive material and a poly-tetrafluoroethylene (PTFE) sheet as a tribonegative one generates the highest peak-to-peak output voltage of 89.6 V, highest peak-to-peak output current of 6.9 µA, and can deliver the maximum power density of 242 mW/m2. The finding of this work presents a potential solution for the development of a green and sustainable energy source.

Marine distributed devices are essential infrastructure for exploring and utilizing the ocean. As the most common carrier of these devices, floating and submerged buoys are subject to a bottleneck of power supply. Recent progress in nanogenerators could convert the high-entropy marine kinetic energy (e.g., wave) robustly, which may form an in-situ power solution to marine distributed devices. This study is devoted to develop a stackable triboelectric nanogenerator (S-TENG), while each layer of it is made into multiple channels carrying PTFE balls in between Aluminum electrodes. In the experiments based on forced motion, the peak power density of the S-TENG reaches 49 W/m3, about 29% promotion from our previous benchmark. The S-TENG has also become less vulnerable to directional variation of the excitation, making its integration on various platforms more flexible in real conditions. In practice, the S-TENG has demonstrated its capability of powering LEDs as well as various sensors measuring salinity, temperature and acidity, which means the S-TENG could self-power many compact marine buoys.

To improve the output power of the polydimethylsiloxane (PDMS)-based triboelectric nanogenerators (TENGs), we fabricated an asymmetric TiO2/PDMS composite film in which a pure PDMS thin film was deposited as a capping layer on a TiO2 nanoparticles (NPs)-embedded PDMS composite film. Although in the absence of the capping layer, the output power decreased when the content of TiO2 NPs exceeded a certain value, the asymmetric TiO2/PDMS composite films showed that the output power increased with increasing content. The maximum output power density was approximately 0.28 W/m2 at a TiO2 content of 20 vol.%. The capping layer could be responsible not only for maintaining the high dielectric constant of the composite film but also for suppressing interfacial recombination. To further improve the output power, we applied a corona discharge treatment to the asymmetric film and measured the output power at a measurement frequency of 5 Hz. The maximum output power density was approximately 78 W/m2. The idea of the asymmetric geometry of the composite film should be applicable to various combinations of materials for TENGs.

Triboelectric nanogenerators (TENGs) are devices that can harvest energy from mechanical motions; such devices can be used to power wearable sensors and various low-power electronics. To increase the lifetime of the device, scientists mainly use the method of making TENG in a hard skeleton to simplify the complex possible relative movements between two triboelectric parts. However, the hard skeletons cannot be embedded in soft and lightweight clothing. To make matters worse, the materials used in the garments must be able to withstand high mechanical forces when worn, such as the pressure of more than 100 KPa exerted by body pressure or everyday knocks. Notably, the TENGs are usually made of fragile materials, such as vacuum-evaporated metal electrodes and nano-sized coatings, on the contact interface; these electrodes and coatings often chip or wear off under the action of external loads. In this work, we succeeded in creating a thin, light-weight, but extremely robust garment-integrated triboelectric nanogenerator (G-TENG) that can be embedded in clothing and pass the water wash test. First, we chemically deposited a durable electrode with flexible properties for G-TENG using a novel technique called polymer-assisted metal deposition (PAMD). The as-formed metal electrodes are firmly bonded to the plastic substrate by a sub-10 nm adhesive polymer brush and can withstand a pressure of 22.5 MPa and a tear force of 0.7 MPa. We then removed the traditionally used fragile nanoparticle materials and the non-durable poly-dimethylsiloxane (PDMS) layer at the triboelectric interface, and then used a cost-effective, durable and slightly flowable pressure-sensitive adhesive to form a plastic contact interface. Such a soft plastic interface can ensure full contact of the triboelectric materials, which is excellent in complex environments and ultimately improves the power generation efficiency of the devices. The as-formed low-cost energy harvesting device could become an industry standard for future smart clothing.

Wind energy as a renewable energy source is easily available and widely distributed in cities. However, current wind-energy harvesters are inadequate at capturing energy from low-speed winds in urban areas, thereby limiting their application in distributed self-powered sensor networks. A triboelectric–electromagnetic hybrid harvester with a low startup wind speed (LSWS-TEH) is proposed that also provides output power within a wide range of wind speeds. An engineering-implementable propeller design method is developed to reduce the startup wind speed of the harvester. A mechanical analysis of the aerodynamics of the rotating propeller is performed, and optimal propeller parameter settings are found that greatly improved its aerodynamic torque. By combining the high-voltage output of the triboelectric nanogenerator under low-speed winds with the high-power output of the electromagnetic generator under high-speed winds, the harvester can maintain direct current output over a wide wind-speed range after rectification. Experiments show that the harvester activates at wind speeds as low as 1.2 m/s, powers a sensor with multiple integrated components in 1.7 m/s wind speeds, and drives a Bluetooth temperature and humidity sensor in 2.7 m/s wind speeds. The proposed small, effective, inexpensive hybrid energy harvester provides a promising way for self-powered requirements in smart city settings.

A smart sensing platform based on a triboelectric nanogenerator (TENG) possesses various advantages such as self-powering, convenience, real-time and biocompatibility. However, the detection limit of the TENG-based sensor is required to be improved. In this study, a high performance TENG-based glucose sensor was proposed by using the Ti3C2Tx (MXene)/graphene oxide (GO) composite electrode. The MXene and GO nanosheets are popular 2D materials which possessed high conductivity and a rich surface functional group. The MXene/GO thin films were prepared through electrostatic self-assembly technology, which can effectively impede the agglomeration of two nanoflakes. The as-prepared MXene/GO film presented outstanding mechanical property. To figure out the relationship between the nanostructure of MXene/GO film and the TENG, a series of MXene/GO-based TENG with different GO sizes was characterized. As a result, the TENG with 400 nm GO demonstrated the highest output performance. Subsequently, the optimized TENG was used in glucose detection application without the assistance of a glucose enzyme. This simple and flexible TENG shows promising potential in biosensors and non-invasive health monitoring.

In the process of geo-energy drilling, the real-time vibration measurement of drill pipes is of significance for an understanding of the downhole conditions and the properties of rock. However, the vibration sensors used in downhole areas at present require additional power sources, such as batteries, and replacing the batteries would significantly reduce production efficiency and increase costs. In our work, a new vibration measurement method using a triboelectric nanogenerator is proposed which will synchronously achieve axial and lateral vibration, and also simultaneously be self-powered. The triboelectric nanogenerator is mainly made of nanomaterials, such as polyimide film and polytetrafluoroethylene (PTFE), and depends on the pulse signal generated by the contact of the two friction layers to measure the vibration frequency. Axial vibration tests show that the output voltage signal amplitude is approximately 3 V, the measurement range is from 0 to 9 Hz, the measurement error is less than 4%, and the maximum output power is 5.63 uW. Additionally, the lateral vibration tests show that the output voltage signal amplitude is approximately 2.5 V, the measurement range is from 0 to 6.8 Hz, the measurement error is less than 6%, and the maximum output power is 4.01 uW. The nanogenerator can typically work in an environment where the temperature is less than 145 °C and the relative humidity is less than 90%.

Triboelectric nanogenerator (TENG) can convert tiny mechanical energy into precious electrical energy. Constant improvements to the output performance of TENG is not only the driving force for its sustainable development, but also the key to expand its practical applicability in modern smart devices. However, most previous studies were conducted at room temperature, ignoring the influence of temperature on the output performance of TENG. Additionally, due to thermionic emission effect, the electrons transferred to a dielectric surface can be released into a vacuum after contact electrification. Therefore, TENG cannot maintain an effective electrical output under high-temperature conditions. Here, a series of high-temperature operatable flexible TENGs (HO-TENGs) based on nanofiber/microsphere hybrid membranes (FSHMs) was fabricated by electrospinning and electrospraying. The Voc of HO-TENG is 212 V, which is 2.33 times higher than that of control TENG. After 10,000 cycle stability tests, the HO-TENG shows excellent durability. Especially, this HO-TENG can maintain 77% electrical output at 70 °C compared to room temperature, showing excellent high-temperature operability. This study can not only provide a reference for the construction of advanced high-performance TENG, but also provide a certain experimental basis for efficient collection of mechanical energy in high-temperature environment and promote the application of TENG devices in harsh environments.

Wind, as a ubiquitous energy, is an important power source for intelligent monitoring systems in smart agriculture applications, and its efficient collection can greatly improve the long-term performance of monitoring systems. However, it is difficult to achieve the broadband and efficient harvesting of wind energy using the existing energy collection technology. Herein, a broadband energy conversion device (ECD), consisting of a triboelectric nanogenerator (TENG) and an electromagnetic generator (EMG), is proposed for wind energy collection under different wind speeds. The introduction of an optimized Scotch yoke mechanism greatly improves the utilization of wind energy by the TENG, thus reducing energy dissipation. Moreover, the addition of a deflector into the fan greatly reduces the start-up wind speed and improves the ability of the device to capture breeze energy. By doping multi-walled carbon nanotubes, the output voltage and current of the TENG can be improved by 108.89% and 116.61%, respectively. Furthermore, the adopted all-directional conductive foam can greatly prolong the service life of the ECD. The peak power of the ECD is 68.49 mW at 9.6 m/s, with the EMG and TENG producing approximately 64.80 mW and 3.69 mW, respectively. The proposed ECD provides a new technical strategy for the practical application of wind energy harvesters.

Harvesting acoustic energy in the environment and converting it into electricity can provide essential ideas for self-powering the widely distributed sensor devices in the age of the Internet of Things. In this study, we propose a low-cost, easily fabricated and high-performance coniform Helmholtz resonator-based Triboelectric Nanogenerator (CHR-TENG) with the purpose of acoustic energy harvesting. Output performances of the CHR-TENG with varied geometrical sizes were systematically investigated under different acoustic energy conditions. Remarkably, the CHR-TENG could achieve a 58.2% higher power density per unit of sound pressure of acoustic energy harvesting compared with the ever-reported best result. In addition, the reported CHR-TENG was demonstrated by charging a 1000 μF capacitor up to 3 V in 165 s, powering a sensor for continuous temperature and humidity monitoring and lighting up as many as five 0.5 W commercial LED bulbs for acoustic energy harvesting. With a collection features of high output performance, lightweight, wide frequency response band and environmental friendliness, the cleverly designed CHR-TENG represents a practicable acoustic energy harvesting approach for powering sensor devices in the age of the Internet of Things.

Highlights Flexible Ag microparticle/MXene-based energy-harvesting films were fabricated via simple spraying and hot-pressing.Optimal film shows high conductivity and effective electro/photo-thermal abilities.It can be easy assembled single-electrode TENG and the output voltage is enhanced by assembled two triboelectrification layers. Supplementary Information The online version contains supplementary material available at 10.1007/s40820-021-00729-w., Ultra-thin flexible films have attracted wide attention because of their excellent ductility and potential versatility. In particular, the energy-harvesting films (EHFs) have become a research hotspot because of the indispensability of power source in various devices. However, the design and fabrication of such films that can capture or transform different types of energy from environments for multiple usages remains a challenge. Herein, the multifunctional flexible EHFs with effective electro-/photo-thermal abilities are proposed by successive spraying Ag microparticles and MXene suspension between on waterborne polyurethane films, supplemented by a hot-pressing. The optimal coherent film exhibits a high electrical conductivity (1.17×104 S m−1), excellent Joule heating performance (121.3 °C) at 2 V, and outstanding photo-thermal performance (66.2 °C within 70 s under 100 mW cm−1). In addition, the EHFs-based single-electrode triboelectric nanogenerators (TENG) give short-circuit transferred charge of 38.9 nC, open circuit voltage of 114.7 V, and short circuit current of 0.82 μA. More interestingly, the output voltage of TENG can be further increased via constructing the double triboelectrification layers. The comprehensive ability for harvesting various energies of the EHFs promises their potential to satisfy the corresponding requirements. Supplementary Information The online version contains supplementary material available at 10.1007/s40820-021-00729-w.

The human–machine interface plays an important role in the diversified interactions between humans and machines, especially by swaping information exchange between human and machine operations. Considering the high wearable compatibility and self-powered capability, triboelectric-based interfaces have attracted increasing attention. Herein, this work developed a minimalist and stable interacting patch with the function of sensing and robot controlling based on triboelectric nanogenerator. This robust and wearable patch is composed of several flexible materials, namely polytetrafluoroethylene (PTFE), nylon, hydrogels electrode, and silicone rubber substrate. A signal-processing circuit was used in this patch to convert the sensor signal into a more stable signal (the deviation within 0.1 V), which provides a more effective method for sensing and robot control in a wireless way. Thus, the device can be used to control the movement of robots in real-time and exhibits a good stable performance. A specific algorithm was used in this patch to convert the 1D serial number into a 2D coordinate system, so that the click of the finger can be converted into a sliding track, so as to achieve the trajectory generation of a robot in a wireless way. It is believed that the device-based human–machine interaction with minimalist design has great potential in applications for contact perception, 2D control, robotics, and wearable electronics.

The components in traditional human–machine interaction (HMI) systems are relatively independent, distributed and low-integrated, and the wearing experience is poor when the system adopts wearable electronics for intelligent control. The continuous and stable operation of every part always poses challenges for energy supply. In this work, a triboelectric technology-based all-in-one self-powered HMI system for wireless remote telemetry and the control of intelligent cars is proposed. The dual-network crosslinking hydrogel was synthesized and wrapped with functional layers to fabricate a stretchable fibrous triboelectric nanogenerator (SF-TENG) and a supercapacitor (SF-SC), respectively. A self-charging power unit containing woven SF-TENGs, SF-SCs, and a power management circuit was exploited to harvest mechanical energy from the human body and provided power for the whole system. A smart glove designed with five SF-TENGs on the dorsum of five fingers acts as a gesture sensor to generate signal permutations. The signals were processed by the microcontroller and then wirelessly transmitted to the intelligent car for remote telemetry and control. This work is of paramount potential for the application of various terminal devices in self-powered HMI systems with high integration for wearable electronics.

In the current IoT era, the key to sports intelligence is the effective collection and analysis of sports data. Sports data can accurately reflect an athlete’s athletic status and help coaches to develop competitive tactics and training programs. Wearable electronic devices used to collect sports data currently have several drawbacks, including their large size, heavy weight, complex wiring, high cost, and need for frequent power replacement. In this work, transparent polyamide-66 (PA-66) and transparent polytetrafluoroethylene (PTFE) films were used as friction layers, polydimethylsiloxane (PDMS) was used as a support layer, and conductive hydrogels were used as electrodes, which were simply combined to create stable and durable triboelectric nanogenerators (SD-TENG) with good mechanical and triboelectric properties. In the test, the output power was 1mW under a load resistance of 10MΩ. In addition, the integrated intelligent speed skating land training assistance system monitors the changes in the joints and joint chains of skaters during land training in real time. The successful demonstration of the use of SD-TENG in speed skating land training will help to promote the development and application of TENG in the fields of intelligent sport monitoring, smart wearable devices, and big data analysis.

Because of their low flexibility, traditional vibration sensors cannot perform arbitrary bending adjustments when facing curved surfaces and other complex working conditions during the drilling process; therefore, this research proposes a ring-shaped vibration sensor (RSV−TENG) that can deform freely in the bending direction, and which can be used in working conditions where the inner bending angle of the drill pipe changes greatly. Test results show that the vibration frequency measurement range is from 4 Hz to 16 Hz, with a measurement error less than 4%, the vibration amplitude measurement range is less than 20 mm, with a measurement error less than 5%, the output voltage and current signal are 120 V and 60 nA, respectively, when three RSV−TENGs are connected in parallel, and the maximum output power is 6 × 10−7 W when the external resistance is 106 Ω. Compared with traditional downhole sensors, this sensor has self-powered and self-sensing functions, eliminating the shortcomings of battery and cable power supply; in addition, this sensor can be installed in the drill pipe space with different curvature radii, so it is more suited to complex and changeable downhole working conditions.

The rapid development of wearable electronic devices (such as in applications for health care monitoring, intelligent sports, and human–computer interaction) has led to a huge demand for sustainable energy. However, the existing equipment cannot meet the requirements of energy harvesting, wearable sensing, and environmental protection concurrently. Herein, by an environmentally friendly in situ gap-generation method and doping technology, we have manufactured an Ecoflex–PVDF composite material as a negative triboelectric layer and used gas as a support layer for the triboelectric nanogenerator (EPGS-TENG). The device has excellent electrical output performance and working stability (pressure sensitivity of 7.57 V/N, angle response capacity of 374%, output power of 121 μW, temperature adaptability from 20 °C to 40 °C, durability over 3 h, and stability of 10 days). EPGS-TENG can meet the requirements of biomechanical energy collection and wearable self-powered sensing simultaneously. EPGS-TENG shows great application potential for the new generation of wearable devices.

Vortex-induced vibration (VIV) is a process that wind energy converts to the mechanical energy of the bluff body. Enhancing VIV to harvest wind energy is a promising method to power wireless sensor nodes in the Internet of Things. In this work, a VIV-driven square cylinder triboelectric nanogenerator (SC-TENG) is proposed to harvest broadband wind energy. The vibration characteristic and output performance are studied experimentally to investigate the effect of the natural frequency by using five different springs in a wide range of stiffnesses (27N/m

Exhaust gas flow takes a vital position in the assessment of ship exhaust emissions, and it is essential to develop a self-powered and robust exhaust gas flow sensor in such a harsh working environment. In this work, a bearing type triboelectric nanogenerator (B-TENG) for exhaust gas flow sensing is proposed. The rolling of the steel balls on PTFE film leads to an alternative current generated, which realizes self-powered gas flow sensing. The influence of ball materials and numbers is systematically studied, and the B-TENG with six steel balls is confirmed according to the test result. After design optimization, it is successfully applied to monitor the gas flow with the linear correlation coefficient higher than 0.998 and high output voltage from 25 to 106 V within the gas flow of 2.5–14 m/s. Further, the output voltage keeps stable at 70 V under particulate matter concentration of 50–120 mg/m3. And the output performance of the B-TENG after heating at 180 °C for 10 min is also surveyed. Moreover, the mean error of the gas flow velocity by the B-TENG and a commercial gas flow sensor is about 0.73%. The test result shows its robustness and promising perspective in exhaust gas flow sensing. Therefore, the present B-TENG has a great potential to apply for self-powered and robust exhaust gas flow monitoring towards Green Ship.

As versatile energy harvesters, triboelectric nanogenerators (TENGs) have attracted considerable attention in developing portable and self-powered energy suppliers. The question of how to improve the output power of TENGs using cost-effective means is still under vigorous investigation. In this paper, high-output TENGs were successfully produced by using a simple and low-cost lotus-leaf-bionic (LLB) method. Well-distributed microstructures were fabricated via the LLB method on the surface of a polydimethylsiloxane (PDMS) negative triboelectric layer. 2D MXene (Ti3C2Tx) and graphene were doped into the structured PDMS to evaluate their effects on the performance of TENG. Owing to merits of the MXene doping and microstructures on the PDMS surface, the output power of MXene-doped LLB TENGs reached as high as 104.87 W/m2, which was about 10 times higher than that of graphene-doped devices. The MXene-doped LLB TENGs can be used as humidity sensors, with a sensitivity of 4.4 V per RH%. In addition, the MXene-doped LLB TENGs were also sensitive to human body motions; hence, a foot health monitoring system constructed by the MXene-doped LLB TENGs was successfully demonstrated. The results in this work introduce a way to produce cost-effective TENGs using bionic means and suggest the promising applications of TENGs in the smart monitoring system of human health.

The triboelectric nanogenerator (TENG) concept was used to build four contact separation TENG models to harvest mechanical vibration from an aircraft wing on an unmanned air and surface vehicle. The first three models used a hexagonal base structure with cylindrical pegs and solid rectangular bar on top. The last design used a rectangular box structure with a free moving bar to convert mechanical vibration output into electrical power. To simulate the vibrational motion of an unmanned aerial vehicle wing, a linear arm motor was used at various speeds to test each model for harvesting mechanical motion. The experimental results showed that the model that produced the maximum voltage was the attached solid bar design. The free bar structure design allowed the use of two electrodes in one structure. The ability to use two electrodes for one model enhanced the electrical power production. The finite element method analysis showed that the rectangular bar models would produce the best electrical output based on their contact frequency, matching with the experimental results. In conclusion, the results showed that the two rectangular bar TENG models can harvest mechanical vibrational energy and convert it into electrical power. Further research into using additional free bar TENG models together in series would demonstrate the ability to harvest additional voltage to store and use for sensor power. Lieutenant, United States Navy Approved for public release. Distribution is unlimited.

Tire pressure monitoring plays a pivotal role in vehicle safety system. However, as a conventional battery‐operated electronic system, regularly replacing battery remains a great inconvenience in wide‐distributed tire pressure sensing. Here, we introduce a self‐powered tire pressure monitor by using a rotary cylinder‐based hybrid nanogenerator as a sustainable power source. The designed energy harvester, by hybridizing a triboelectric nanogenerator (TENG) and electromagnetic generator (EMG), can scavenge rotational energy from rolling axles. Integrating with transformers, the hybrid nanogenerator can achieve an open‐circuit voltage of 16 V and short‐circuit current of 0.1 mA at the rotation rate of 150 rpm, respectively, with the maximal output power of about 1.8 mW at the loading of 20 kΩ. Via a programmable software, the hybrid device can operate as a self‐powered counter and timer for potential speed detecting. Further, it has been demonstrated that the hybrid nanogenerator is capable of triggering a transmitter‐integrated tire pressure sensor for self‐powered monitoring tire pressure in real time. This study expands applications based on TENGs in automobile engineering, which might promote the development of intelligent driving and traffic safety engineering.

Harvesting energy from human body in multiple ways is pivotal for achieving powering emergency electronics effectively. Herein, we report a hybrid nanogenerator that is based on the coupling of a triboelectric nanogenerator (TENG) and electromagnetic generator (EMG). By utilizing a copper coil in multiroles, the energy grabbing units can operate independently without interfering, revealing a superior performance in scavenging biomechanical energy from human motions. The hybrid device by encapsulation exhibits an excellent environmental stability. When wearing the fabricated device, the TENG and EMG can generate the output voltage about 4 and 1.5 V, respectively, which can be directly stored into a capacitor. By integrating with a battery, the established self‐powered device can actively provide a geographic coordinate in real time in the wild where there is no power supply or network connectivity. Our work paves a way for the further exploration based on hybrid nanogenerators in self‐powered wearable/portable emergency electronics that can be applied in exploration, travel, work, as well as rescue in the wild without power apply and Internet.

The study of triboelectric nanogenerators (TENGs) has focused widely on the issue of elevating triboelectrifying capacity. A new recently discovered phenomena of the use of polymers electrolytes for TENGs has been shown to be positive. However, this has not been studied yet in a wide range of materials. Renewable materials, such as biopolymer electrolytes, are still poorly understood regarding their relation to TENG performance. Herein, a polymer electrolyte starch-based bio-TENG was fabricated using a low-cost processing method. The films were electrically characterized at distinct loads, frequencies, thicknesses. Moreover, we complexed the starch polymer with CaCl2 to increase the triboelectrifying capacity and performance. Starch films at 0.5% of salt concentration reached the highest voltage output (1.2 V), exceeding by three-fold of the initial output of the non-complexed pristine biopolymer (0.4 V). Furthermore, the electrical output performance varies positively at both thinner film thicknesses and elevated loads while moisture of films has been proved to be a critical parameter in the electrical performance of TENGs, showing that well dried films performed a higher electrical output than moist samples. Furthermore, despite crack generation after fatigue, starch electrolyte films of TENGs showed an inalterable electrical performance suitable for a bunch of applications. To demonstrate one of these applications we achieved to turn on 100 LEDs using starch electrolyte and silicone ecoflex as opponents in a TENG.

Recently, as the use of wearable devices and the demand for eco-friendly energy have increased, many studies have been conducted on triboelectric nanogenerators (TENGs), which can economically harvest energy. Paper is considered a promising substrate and frame material that can be used to manufacture self-powered TENGs, owing to its flexibility, low cost, and accessibility. Herein, we present a sandwich-structured foldable paper-based TENG (FP-TENG) that comprises flexible materials and uses paper as a substrate. The FP-TENG can generate up to 572 mW/m2 of power via contact–separation of the triboelectric electrified body at the top and bottom. With more folds of the FP-TENG, the triboelectric cross-sectional area increases, and, thus, the electrical output increases. In addition, the proposed TENG exhibits excellent durability without signal degradation under 5000 cycles of repeated pushing motions. To demonstrate its practicality, the FP-TENG was manufactured in the form of a wristwatch Velcro and connected to an electronic watch panel to supply power. Various deformations are possible with origami, and they can drive wristwatches through external forces. Therefore, the FP-TENG is expected to be utilized as a sustainable and promising eco-friendly energy source for small electronic devices.

Developing clean and renewable ocean wave energy is a top priority and an effective way to achieve carbon neutrality. Triboelectric nanogenerators (TENGs) have emerged as promising green and clean energy-harvesting devices. To harvest low-frequency wave energy efficiently, much effort has been made on the modification of the contact surface, which leads to a higher fabrication cost. In this work, we designed a novel “Lucky-Bag” core (LBC) for spherical TENGs with a low-cost and easy fabricating process. The nanofiber/silicone hybrid porous outer layer of the LBC can switch freely from plane to surface and improve the output performance of both the plane and spherical TENGs. Several factors, such as the input frequency, direction, and resistive load, together with the thickness were systematically investigated; the unique porous soft-contact structure increased the triboelectric contact area, and the working mechanism was studied by using the COMSOL software. The experimental results showed that the peak-to-peak open-circuit voltage (Voc) and short-circuit current (Isc) could reach 580 V and 23.5 μA at 1.5 Hz, even under 2D linear motion. Besides, the maximum output power of the spherical TENGs reached 9.10 mW, which can fully power electronic devices such as capacitors and LEDs under water wave triggering. These findings provide useful guidance for optimizing the performance of spherical TENGs for practical applications in harvesting water wave energy.

High-performance triboelectric nanogenerators (TENGs) are usually made of expensive, unsustainable, and non-biodegradable materials, limiting their development for wearable applications and posing environmental problems for their disposal. Here, we mitigate this challenge by reporting a highly polarizable, low-cost, and biodegradable tribopositive material, made of poly-ε-caprolactone (PCL)/ethyl cellulose (EC) biocomposite. PCL (weakly polarizable, but mechanically robust) and EC (highly polarizable, but mechanically weak) learn from each other's strengths and complement each other's weaknesses. The obtained PCL/EC-based TENG reached a peak power density of 157.17 mW/m2 at optimized 6 wt % EC (at 40 MΩ load, 11 N), enhanced by 46 times. Thanks to the good flexibility, high tensile mechanical property, remarkable stability, and biodegradability, TENG can be comfortably attached on the human body as a wearable motion sensor, in addition to energy harvesting applications. Our work greatly contributes to the development of environmental sustainability, which results from reduction of electronic waste generation., Cell Reports, 3 (8), ISSN:2666-3864, ISSN:2211-1247

As one of the promising non-volatile memories (NVMs), resistive random access memory (RRAM) has attracted extensive attention. Conventional RRAM is deeply dependent on external power to induce resistance-switching, which restricts its applications. In this work, we have developed a self-powered RRAM that consists of a Pr0.7Ca0.3MnO3 (PCMO) film and a triboelectric nanogenerator (TENG). With a traditional power supply, the resistance switch ratio achieves the highest switching ratio reported so far, 9 × 107. By converting the mechanical energy harvested by a TENG into electrical energy to power the PCMO film, we demonstrate self-powered resistance-switching induced by mechanical movement. The prepared PCMO shows excellent performance of resistance switching driven by the TENG, and the resistance switch ratio is up to 2 × 105, which is higher than the ones ever reported. In addition, it can monitor real-time mechanical changes and has a good response to the electrical signals of different waveforms. This self-powered resistance switching can be induced by random movements based on the TENG. It has potential applications in the fields of self-powered sensors and human-machine interaction.

Funder: Priority Academic Program Development of Jiangsu Higher Education Institutions; Id: http://dx.doi.org/10.13039/501100012246, Funder: 111 Project; Id: http://dx.doi.org/10.13039/501100013314, Funder: Joint International Research Laboratory of Carbon‐Based Functional Materials and Devices, Funder: European Union; Id: http://dx.doi.org/10.13039/501100000780, The Internet of Things (IoT) provides everyday objects and environments with “intelligence” and data connectivity to improve quality of life and the efficiency of a wide range of human activities. However, the ongoing exponential growth of the IoT device ecosystem—up to tens of billions of units to date—poses a challenge regarding how to power such devices. This Progress Report discusses how energy harvesting can address this challenge. It then discusses how indoor photovoltaics (IPV) constitutes an attractive energy harvesting solution, given its deployability, reliability, and power density. For IPV to provide an eco‐friendly route to powering IoT devices, it is crucial that its underlying materials and fabrication processes are low‐toxicity and not harmful to the environment over the product life cycle. A range of IPV technologies—both incumbent and emerging—developed to date is discussed, with an emphasis on their environmental sustainability. Finally, IPV based on emerging lead‐free perovskite‐inspired absorbers are examined, highlighting their status and prospects for low‐cost, durable, and efficient energy harvesting that is not harmful to the end user and environment. By examining emerging avenues for eco‐friendly IPV, timely insight is provided into promising directions toward IPV that can sustainably power the IoT revolution.

Cellulose paper has been functionalized by nanoparticles such as Ag nanoparticles, TiO2, and BaTiO3 for versatile applications including supercapacitor, sensors, photoactivity, and packaging. Herein, zinc oxide (ZnO) nanosheet-modified paper (ZnO@paper) with excellent antibacterial properties was fabricated via a mild ZnCl2-urea eutectic solvent. In this proposed method, cellulose fibers as the raw material for ZnO@paper were treated by an aqueous solvent of ZnCl2-urea; the crystalline region was destroyed and [ZnCl]+-based cations were adsorbed on the surface of cellulose fibers, facilitating more ZnO growth on ZnO@paper. A flexible paper-based triboelectric nanogenerator (P-TENG) was made of ZnO@paper paired with a PTFE film. The P-TENG presents high triboelectric output performance and antibacterial activity. For instance, the output voltage and current of the P-TENG were 77 V and 0.17 μA, respectively. ZnO@paper showed excellent antibacterial activity against E. coli and S. aureus, suggesting that a P-TENG can restrain and kill the bacteria during the working process. The results also indicated that ZnO could improve the surface roughness of cellulose paper, enhancing the output performance of a flexible P-TENG. In addition, the potential application of a P-TENG-based pressure sensor for determining human motion information was also reported. This study not only produced a high-performance P-TENG for fabricating green and sustainable electronics, but also provides an effective and novel method for ZnO@paper preparation.