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Abstract Visible light‐based human–machine interactive media is capable of transmitting electrical readouts to machines and providing intuitive feedback to users simultaneously. Currently, many inorganic mechanoluminescent (ML) materials‐based interactive media, typically ZnS‐loaded phosphors (ZLPs), have been successfully demonstrated. However, organic ML materials‐based solutions were rarely exploited despite their huge merits of strong structural modification, abundant luminescence property, low cost, easy preparation, and so on. Here, we propose a novel interactive tactile display (ITD) based on organic ML materials (Cz‐A6‐dye) and triboelectric nanogenerator, with ultra‐brightness (130% enhancement) and ultra‐low threshold pressure (57% reduction) as compared to ZLPs. The proposed ITD achieves the conversion of weak mechanical stimuli into visible light and electrical signals simultaneously, without extra power supplies. Furthermore, the relationship between the luminous performance of organic ML materials and mechanical force is quantified, benefiting from the uniform ML layer prepared. Enabled by convolutional neural networks, the high‐accuracy recognition (97.1%) for handwriting and identity of users is realized at the same time. Thus, the ITD has great potential for intelligent wearable electronics and classified military applications.

Abstract Surveillance is an intricate challenge worldwide especially in those complicated environments such as nuclear plants, banks, crowded areas, barns, etc. Deploying self‐powered wireless sensor nodes can increase the system's event detection capabilities by collecting environmental changes, while the incompatibility among components (energy harvesters, sensors, and wireless modules) limits their application. Here, a broadly compatible self‐powered visualized platform (SPVP) is reported to construct a passive internet of events (IoE) network for surveillance systems. By encoding electric signals into reference and working LEDs, SPVP can visualize resistance change generated by commercial resistive sensors with a broad working range (

Abstract To meet the requirements of power grid operation control, constructing an extensive sensor network in the power grid is a future development trend. However, due to the high cost, the difficulty of continuous power supply for a long time, the large amount of energy consumption, and the environmental problems caused by abandoned batteries, the traditional power supply mode based on batteries for sensors is inconsistent with China's goal of carbon peak and carbon neutrality. It cannot meet the needs of the future grid. Therefore, it is significant to solve the energy supply problem of numerous sensors to promote the construction of new power grid and improve the utilization rate of renewable energy. As an emerging energy harvesting device, triboelectric nanogenerators (TENG) are suitable for developing self‐powered sensors and powering low‐power sensors due to their mall size, high efficiency, low cost, and environmental friendliness. At the same time, due to the abundant, stable, and widely distributed magnetic field around the equipment in the grid, it can provide continuous excitation for the TENG. Therefore, applying magnetic field energy‐harvesting TENG in the future power grid has a broad development prospect. This paper analyzes the development trend and the crucial problems facing the power grid in the future. We review the research and application of TENG based on the magnetic field in recent years and explain the mechanism of TENG in detail. Finally, the application prospect of TENG in the future power grid has been prospected. This paper can provide a reference for applying magnetic field energy harvesting triboelectric nanogenerators in future power grids.

Surface wear is a major hindrance in the solid/solid interface of triboelectric nanogenerators, severely affecting output performance and stability. Here, authors show metallic glass as one triboelectric interface can enhance the triboelectrification efficiency and endow the device with humidity- and wear-resistance.

With the growing economy and technology, disease prevention and individual health are becoming more and more important. It is highly urgent to develop a non-toxic, self-powered, and safe high-voltage power source to prevent diseases spread by mosquitoes, especially in isolated or remote areas. Herein, we reported a high-performance rotary triboelectric nanogenerator (R-TENG) based on customized theoretical simulations and a ferroelectric nanocomposite intermediate layer. The customized theoretical simulations based on gradient electrode gaps were established to optimize gap angles and segment numbers of the electrodes, which could prevent air breakdown and enhance the R-TENG output energy by at least 1.5 times. Meanwhile, the electrical output performance of the TENG was further enhanced with a highly oriented BaTiO3 (BTO) nanoparticles intermediate layer by about 2.5 times. The open-circuit voltage of R-TENG reached more than 6 kV and could continuously light 3420 light-emitting devices (LEDs) or 4 serially connected 36 W household fluorescent lamps. Therefore, a self-powered high-voltage disease prevention system is developed based on the high-performance R-TENG to reduce the risk of disease transmission. This work provides a prospective strategy for the further development of TENGs and expands practical applications of self-powered and high-voltage systems.

Abstract The launching of 5G technology provides excellent opportunity for the prosperous development of Internet of Things (IoT) devices and intelligent wireless sensor nodes. However, deploying of tremendous wireless sensor nodes network presents a great challenge to sustainable power supply and self‐powered active sensing. Triboelectric nanogenerator (TENG) has shown great capability for powering wireless sensors and work as self‐powered sensors since its discovery in 2012. Nevertheless, its inherent property of large internal impedance and pulsed “high‐voltage and low‐current” output characteristic seriously limit its direct application as stable power supply. Herein, a generic triboelectric sensor module (TSM) is developed toward managing the high output of TENG into signals that can be directly utilized by commercial electronics. Finally, an IoT‐based smart switching system is realized by integrating the TSM with a typical vertical contact–separation mode TENG and microcontroller, which is able to monitor the real‐time appliance status and location information. Such design of a universal energy solution for triboelectric sensors is applicable for managing and normalizing the wide output range generated from various working modes of TENGs and suitable for facile integration with IoT platform, representing a significant step toward scaling up TENG applications in future smart sensing.

Abstract Triboelectric nanogenerators (TENGs) represent a promising next‐generation renewable energy technology. TENGs have become increasingly popular for harvesting vibration energy in the environment due to their advantages of lightweight, broad range of material choices, low cost, and no pollution. However, issues such as input force irregularity, working bandwidth, efficiency calculation, and dynamic modeling hinder the use of TENGs in industrial or practical applications. In this paper, the modeling process of the dynamical system of a TENG is reviewed from the perspective of energy flow. In addition, this paper reviews the main contributions made in recent years to achieve optimized output based on springs, magnetic forces, and pendulums, and introduces different ways to increase the bandwidth of TENGs. Finally, the main problems of TENGs in the process of harvesting vibration energy are discussed. This review may serve as a practical reference for methods to convert irregular mechanical input sources into optimized output performance toward the commercialization of TENGs.

Abstract Charge transfer mechanisms of contact electrification (CE) are essential for widening applications of the triboelectric nanogenerator, and thus are widely studied by scientists around the world. However, the quantitative modeling of CE, especially that between polymers, is still lacking. Herein, a model was proposed to describe the contributions from different mechanisms, including electron transfer and mass transfer in polymer/polymer CE through the field‐assisted thermionic emission, where three groups of charge transfer mechanisms were distinguished by the polarity of the charge transfer and the corresponding electric field. The results indicated that the total generated charge in CE is actually much larger than the measured net surface charge, confirming the bidirectional material‐dependent charge transfer mechanisms between two surfaces, which is meaningful for understanding the millennium puzzle in triboelectrification and provides a new perspective for promoting the applications to tailor surface charge generation.

Abstract The 2050 carbon‐neutral vision spawns a novel energy structure revolution, and the construction of the future energy structure is based on equipment innovation. Insulating material, as the core of electrical power equipment and electrified transportation asset, faces unprecedented challenges and opportunities. The goal of carbon neutral and the urgent need for innovation in electric power equipment and electrification assets are first discussed. The engineering challenges constrained by the insulation system in future electric power equipment/devices and electrified transportation assets are investigated. Insulating materials, including intelligent insulating material, high thermal conductivity insulating material, high energy storage density insulating material, extreme environment resistant insulating material, and environmental‐friendly insulating material, are categorised with their scientific issues, opportunities and challenges under the goal of carbon neutrality being discussed. In the context of carbon neutrality, not only improves the understanding of the insulation problems from a macro level, that is, electrical power equipment and electrified transportation asset, but also offers opportunities, remaining issues and challenges from the insulating material level. It is hoped that this paper envisions the challenges regarding design and reliability of insulations in electrical equipment and electric vehicles in the context of policies towards carbon neutrality rules. The authors also hope that this paper can be helpful in future development and research of novel insulating materials, which promote the realisation of the carbon‐neutral vision.

A narrow resonance bandwidth of an energy harvesters limits its response to the wide frequency spectrum in ambient environments. This work proposes an addition of a nonlinear restoring force applied to a triboelectric nanogenerator (TENG) to tune and broaden the resonance bandwidth. This restoring force is applied by permanent magnets at both sides of the slider and two external magnets. The noncontact strategy is adopted between the slider and the grating electrodes to avoid the wear of electrodes and energy loss caused by friction. The results show that compared with the linear system, the nonlinear noncontact TENG (NN-TENG) can increase the peak current from 6.3 μA to 7.89 μA, with an increment of about 25%, increase the peak power from 650 μW to 977 μW, increasing by about 50%, and increase the bandwidth from 0.5 Hz to 7.75 Hz, increasing by about1400%. This work may enable a new strategy to boost the bandwidth and output power of TENG through nonlinear oscillators.

IntroductionWith the economic recession and pandemic fatigue, milder viral variants and higher vaccine coverage along the time lay the basis for lifting anti-COVID policies to restore COVID-19 normalcy. However, when and how to adjust the anti-COVID policies remain under debate in many countries.MethodsIn this study, four countries (Singapore, South Korea, Australia, and New Zealand) and one region (Hong Kong SAR), that have shifted from the zero-COVID (ZC) policy to or close to the living-with-COVID (LWC) during or after the Omicron outbreak, were selected as research objects. All-cause mortality data were collected for these objects from 2009 to 2019. The expected mortality was estimated by a simple linear regression method. Excess mortality over time was calculated as the difference between the expected mortality and the observed mortality. Finally, percent excess mortality (PEM) was calculated as the excess mortality divided by the expected mortality.ResultsIn the examined four countries, PEM fluctuated around 0% and was lower than 10% most of the time under the ZC policy before 2022. After shifting to the LWC policy, all the examined countries increased the PEM. Briefly, countries with high population density (Singapore and South Korea) experienced an average PEM of 20–40% during the first half of 2022, and followed by a lower average PEM of 15–18% during the second half of 2022. For countries with low population density under the LWC policy, Australia experienced an average PEM of 39.85% during the first half of 2022, while New Zealand was the only country in our analysis that achieved no more than 10% in average PEM all the time. On the contrary, Hong Kong SAR under their ZC policy attained an average PEM of 71.14% during the first half of 2022, while its average PEM decreased to 9.19% in the second half of 2022 with LWC-like policy.ConclusionPEM under different policies within each country/region overtime demonstrated that the mortality burden caused by COVID-19 had been reduced overtime. Moreover, anti-COVID policies are suggested to control the excess mortality to achieve as low as 10% in PEM.

Difficulties in separating tribo and piezoelectric hybrid signals can lead to an overestimated contribution of the latter. Here, authors propose a method to separate these hybrid signals in the time domain, precisely extracting piezoelectric charge transfer for performance evaluation.

Abstract Fiber‐optic sensors have been developed to monitor the structural vibration with advantages of high sensitivity, immunity to electromagnetic interference (EMI), flexibility, and capability to achieve multiplexed or distributed sensing. However, the current fiber‐optic sensors require precisely polarized coherent lasers as the lighting sources, which are expensive in cost and suffer from the power supply issues while operating at outdoor environments. This work aims at solving these issues, through developing a fully self‐powered, natural‐light‐enabled approach. To achieve that, a spring oscillator‐based triboelectric nanogenerator (TENG), a polymer network liquid crystal (PNLC), and an optical fiber were integrated. The external vibration drove the PNLC to switch its transparency, allowing the variation of the incident natural light in the optical fiber. Compared with the majority of conventional TENG‐based active vibration sensors, the developed paradigm does not suffer from the EMI, without requirements of the signal preamplification which consumes additional energy. The vibration displacement monitoring was performed to validate the sensing effectiveness of the developed paradigm.

TENG suffers from two fundamental limitations: high output impedance and low charge transfer. Herein, these limitations are circumvented by leveraging the opposite-charge-enhancement effect and transistor-like device design, thereby achieving the instantaneous power density over 10 MW/m2 at the low frequency of ~ 1 Hz.

As a state of matter, liquids exist in an extremely wide range, including water such as that in oceans and rivers, as well as various solutions, oils, liquid metals, etc. Due to the fluidity of liquids, the triboelectric effect based on them often shows unexpected results and can be used in complex environments. Herein, the latest research on working principles of the triboelectric effect at liquid–solid, liquid–liquid, and liquid–gas interfaces are reviewed. The factors affecting triboelectric charge generation and the output performance of liquid‐interfaces‐based TENGs (LI‐TENG) in terms of material, environment, and structure are systematically discussed. Besides, to harvest the ubiquitously existing energy in various forms, studies about the hybridization of LI‐TENG with other energy harvesters for syngeneic single‐source and multisource energy harvesting are also reviewed. Moreover, the performances of LI‐TENGs as energy harvesters and as novel sensors with various applications are reviewed. Finally, opportunities and challenges in the future development of LI‐TENG are discussed.

Conditioning efficiently high-voltage triboelectric nanogenerators for low-voltage applications remains a challenge. Here, the authors demonstrate two orders of magnitude improvement of the energy harvesting efficiency by applying a conditioning circuit with self-sustained and automatic hysteresis MEMS micro-plasma switches.

Abstract The advances in wearable/flexible electronics have triggered tremendous demands for flexible power sources, where flexible nanogenerators, capable of converting mechanical energy into electricity, demonstrate its great potential. Here, recent progress on flexible nanogenerators for mechanical energy harvesting toward self‐powered systems, including flexible piezoelectric and triboelectric nanogenerator, is reviewed. The emphasis is mainly on the basic working principle, the newly developed materials and structural design as well as associated typical applications for energy harvesting, sensing, and self‐powered systems. In addition, the progress of flexible hybrid nanogenerator in terms of its applications is also highlighted. Finally, the challenges and future perspectives toward flexible self‐powered systems are reviewed.

Harvesting energy from human body motions is an appropriate option as an assistant or even subversive way for powering the booming wearable electronics, in which smart textiles are important components. Here, we fabricate a robust power textile with working mechanism of triboelectrification effect and electrostatic induction effect by simply integrating the normal textiles and polydimethylsiloxane (PDMS)/conductive yarns electrodes. Maximum peak loading voltage and current reaching 230 V and 11.6 μA are obtained by rubbing our power textile, and this alternating and irregular electricity can be accumulated in a capacitor or directly light up 20 blue LEDs. The recovered energy generation ability of the power textile after washing successfully demonstrate its robustness, showing the potential application in powering the electronics in smart textiles.

Abstract The color‐tuning capability of solid‐state lighting (SSL) systems are highly demanded for smart lighting according to the environmental conditions, as well as wireless sensing of the environmental information. In the meanwhile, state‐of‐the‐art triboelectric nanogenerator (TENG)‐based sensing systems rely on bulky and expensive devices, which require cable connections and additional power consumptions. This work aims at solving these challenges, through developing a tribo‐induced color tuner that can be integrated into the vastly distributed commercial SSL system. This tribo‐induced color tuner includes a concentric color conversion plate consisting of (Sr,Ca)AlSiN3:Eu phosphor and TiO2, a tribo‐induced liquid lens, and a rotary freestanding sliding TENG. The color oscillation between purple and pink is achieved upon the tribo‐charging by the TENG, which reveals the input mechanical motion signals. The signal can be conveniently sent by everywhere‐existed lamps and processed by everyone‐owned smartphone cameras or closed‐circuit televisions. Through this approach, the function of wireless sensing is achieved without the need of preamplification, with no additional power supply required, as demonstrated for wireless sensing of the rotation speed. The smart lighting for underwater photographing is also demonstrated by the color‐tunable SSL system with the best imaging quality achieved.

Figures of merit are used to evaluate output performance of triboelectric nanogenerators, but do not account for the breakdown effect that inhibits maximum output. Here the authors propose a standardized assessment method for output capability of nanogenerators that takes breakdown limits into consideration.

Abstract Recently, the direct‐current (DC) TENG based on triboelectrification and discharge has been reported, which can not only generate a DC power, but also provide a higher charge density compared to traditional TENG. Here, we report a novel coplanar‐electrode DC TENG (CDC‐TENG) design which can be easily fabricated by two electrodes, and then a theoretical model is built to illustrate its principle and optimize its output performance. Both theoretical and experimental studies show that the designed device can enhance the energy output, and then the output power is optimized. Furthermore, we develop a three‐electrode CDC‐TENG to output DC during the reciprocating motion. We apply this CDC‐TENG design for rotational energy harvesting and produce a stable constant DC output. This represents an important progress to effectively store the energy harvested by the CDC‐TENG with the aim to drive portable/wearable/implantable electronics with the stable output.

Gas discharge plasma sources are bulky and of limited use in remote areas with no external power supply. Here the authors create triboelectric plasma by triggering TENGs with mechanical stimuli and discuss its application as a portable plasma source.

Harvesting bio-mechanical energy is a promising route to powering wearable electronics, however design obstacles remain. Here the authors report on a triboelectric nanogenerator with optimized materials and design that can sustainably power an electronic watch and fitness tracker solely by human motion.

Self-charging systems based on the connection of a nanogenerator and an energy storage unit through a rectifier can have low energy storage efficiencies. Here, the authors design the charging cycle to maximize the energy storage efficiency of a triboelectric nanogenerator by introducing a motion-induced switch.

Nanoenergy is a field of studying the small-scale, highly efficient energy harvesting, storage, and applications by using nanomaterials and nanodevices. Nanogenerators are developed to harvest these small-scale energies in the ambient environment, which were first invented in our group in 2006. In the past decade, we have developed nanogenerators based on piezoelectric and triboelectric effects for mechanical energy harvesting, and those based on pyroelectric and thermoelectric effects for thermal energy harvesting. We also explored other novel nanogenerators such as that based on ion streams. The proposed nanogenerators will facilitate the development of self-powered systems, which enables efficient energy utilization and sustainable operations of mobile devices for “smart” wearable technology, health monitoring, biomedical sensing, environmental protection, and even security.

Flow-induced energy harvesting has attracted more and more attention among researchers in both fields of the wind and the fluid. Piezoelectric energy harvesters and triboelectric nanogenerators are exploited to obtain superior performance and sustainability, and the electromagnetic conversion has been continuously improved in the meantime. Aiming at different circumstances, researchers have designed, manufactured, and tested a variety of energy harvesters. In this paper, we analyze the state-of-the-art energy harvesting techniques and categorize them based on the working environment, application targets, and energy conversion mechanisms. The trend of research endeavors is analyzed, and the advantages, existing problems of energy harvesters, and corresponding solutions of energy harvesters are assessed.