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A self‐powered system for the Internet of Things (IoT) is demonstrated for efficient energy harvesting of naturally available mechanical energy. In this system, new contact‐separation mode triboelectric nanogenerators (TENGs), based on fluorinated ethylene propylene, are investigated using the segmented multi‐TENG configuration to reduce the effect of parasitic capacitance. The TENG extraction is optimized using a unit step excitation involved with the Dawson function to achieve a high voltage (400 V) and a high current (26.6 µA). To fully extract the power of the TENGs, the power management integrated circuit (PMIC) specially designed for adaptively controlled, high‐voltage (HV) maximum power point tracking (MPPT) is proposed. The PMIC implemented in a bipolar CMOS‐DMOS 180 nm process can handle a wide input range (5–70 V) by consuming 420 nW. The MPPT control allows a wide range of impedance matching from 10 to 300 MΩ, achieving a tracking efficiency of up to 98.2%. The end‐to‐end efficiency of 88% demonstrates state‐of‐the‐art performance. To supply a higher instantaneous power than that available from the TENGs, a duty‐cycling technique is successfully demonstrated. The proposed energy harvesting system provides a promising approach to realizing sustainable and autonomous energy sources for various IoT applications. [ABSTRACT FROM AUTHOR]

Energy shortage and environmental degradation are two important challenges facing humanity. Here, a multi‐layer stacked triboelectric nanogenerator (MLS‐TENG) based on a rotation‐to‐translation mechanism is reported for fluid energy harvesting and environmental protection. The mechanism transforms fluid‐induced rotation into a reciprocal translation of the MLS‐TENG, enabling the conversion of fluid energy into electrical energy. In addition, benefiting from a multi‐layer stacked structural design, the open‐circuit voltage is increased from 860 to 2410 V and an efficient energy harvesting rate of 2 mJ min−1 is obtained in an actual river. Furthermore, with the assistance of the MLS‐TENG, a self‐powered wireless temperature and humidity monitoring system and a metal anticorrosion system are successfully established. Ambient monitoring data can be transmitted continuously at an interval of 49.7 s, and the corrosion rate of steel is significantly slowed down. This study provides guidance for efficient harvesting of ambient fluid energy, with promising applications in environmental monitoring and protection. [ABSTRACT FROM AUTHOR]

Integrating power into fabrics offers exciting opportunities for wearable technologies, which has long remained challenging to make flexible, high temperature resistant textile‐based powers. Here, an all yarns‐based triboelectric nanogenerator (Y‐TENG) is proposed to harvest electrical energy and sense biological motion for temperatures between 25 and 400 °C, the upper limit of temperature is greatly improved. The Y‐TENG is capable of outputting a transferred charge density of 30 nC cm−2, the external load resistance is 180 MΩ, and the peak power reaches 0.17 mW, and the average response time is lower than 15 ms. Based on a simple processing strategy, when introducing silica aerogel during electrospinning of polyimide nano‐covered layer to make multi‐ply and stabilized triboelectric yarns. Unlike ordinary fibers and yarns, the core‐shell structured design also shows a high sensitivity to all kinds of mechanical triggering sources. Furthermore, a self‐powered movement characteristic monitoring system by coordinating smart protective suit is further developed to provide real‐time sensing and rescuing assistance. This aerogel nano‐covered triboelectric yarn has great application prospects for energy generation and motion detection in high‐temperature and many other high‐risk environments. [ABSTRACT FROM AUTHOR]

With increasing global warming, catastrophic floods have threatened people's lives seriously and caused huge economic losses. However, present water hazard alarming systems generally rely on commercial batteries, limiting the intelligent development of disaster prevention planning and maintenance costs. In order to break the limitation, this work applies triboelectric nanogenerators (TENGs) to water hazard alarming. A spherical TENG device with four spiral units is designed to harvest water wave energy, and charge excitation modules (CEMs) are created and integrated with the TENG to improve its electric output. The output current and output power of the spherical TENG with CEMs can reach 15.09 mA and 24.48 mW, which are increased by 250.5 and 4.0 times, compared to the TENG without CEMs. Based on the charge excitation TENG, a self‐powered intelligent buoy is constructed. Utilizing the buoy to transmit 433 MHz radio frequency signals to 25 meters away, a water level alarm system and a water level information exchange system with a mobile phone are successfully realized. This work extends applications of TENGs toward water wave energy harvesting and provides a new strategy for water hazard alarming, which is conducive to the fields of carbon neutralization, Internet of Things, and disaster prevention. [ABSTRACT FROM AUTHOR]

An agglomeration phenomenon characterized by nanoparticle dispersion is a decisive factor that reflects the degree of the maintained overall performance of nanofluids and other nanocomposites. However, the quantitative characterization and non‐destructive measurement for nanofluid dispersion (NFD) still remain challenged. Herein, an in situ NFD measurement system based on a variable frequency liquid–solid triboelectric nanogenerator (VFLS‐TENG) is developed. This work utilizes VFLS‐TENG as a passive probe and proposes an equivalent capacitance circuit model for detecting NFD based on the electric double layer model at liquid–solid interfaces. In the circuit model, a quantitative calculation process for both particle size and spacing is introduced through parameter identification using the Quantum Genetic and Levenberg–Marquardt hybrid algorithm, and parameter separation using the Runge–Kutta algorithm. The results demonstrates a good agreement with the traditional methods, among which the measured particle size is more accurate than the hydrodynamic diameter of dynamic light scattering by 28.6% with a high sensitivity of 1667 nm nF−1. The proposed method is capable of measuring the effective charge on the nanoparticle surface in situ, and simultaneously obtaining the particle size and spacing for the online monitoring NFD, thus further facilitating the controllable preparation during the nano‐composites modification, and quantitative optimization of nanofluid design performance. [ABSTRACT FROM AUTHOR]

A triboelectric nanogenerator (TENG) can convert energy in the surrounding environment to electricity. Therefore, in recent years, research related to TENGs has significantly increased owing to its simple and low‐cost manufacturing process, high portability, and high efficiency. The principle of the TENG lies in the coupling effect of contact electrification and electrostatic induction. Its output performance is directly proportional to the square of the surface charge density, which is related to friction materials. To increase the output power of a TENG and continuously provide electricity for other electronic equipment, many scholars have conducted detailed studies on the triboelectric properties of materials. Particularly, there has been research interest in the chemical functionalization of TENGs due to their unique advantages, such as high triboelectric charge density, durability, stability, and self‐cleaning properties. This Progress Report highlights the research progress in chemical modification methods for improving the charge density of TENGs, and classifies their modification methods according to their mechanisms. The effects of chemical reaction, surface chemical treatment, and chemical substance doping on the output performance of TENGs are systematically elaborated. Furthermore, the applications of chemically modified TENG in self‐powered sensors and emerging fields, including wearable electronic devices, human‐machine interfaces, and implantable electronic devices, are introduced. Lastly, the challenges faced in the future developments of chemical modification methods are discussed, thereby guiding researchers to the use of chemical modification methods for the improvement of charge density for further exploration. [ABSTRACT FROM AUTHOR]

Abstract: Sensitive monitoring and real‐time foot pressure mapping have important applications for medical treatment/diagnostics, sports training, and even security. In this work, a facile plantar pressure mapping system with a large pressure detection range using piezoelectric nanogenerators serving as the sensor array to acquire pressure signals, and a self‐designed data acquisition (DAQ) circuit board to process and wirelessly send the signals to a mobile terminal, such as a smart phone, are developed. Working with an application program developed in Android, the whole system can accurately monitor and visually display the real‐time pressure distribution during walking. More importantly, by combining a hybridized triboelectric–electromagnetic nanogenerator, a self‐powered, continuous, and real‐time pressure distribution monitoring system is developed, which provides a feasible solution for sport/exercise biomechanics information acquisition, injury prevention, and ulceration prediction in the feet. [ABSTRACT FROM AUTHOR]

Additional surgeries for implantable biomedical devices are inevitable to replace discharged batteries, but repeated surgeries can be a risk to patients, causing bleeding, inflammation, and infection. Therefore, developing self-powered implantable devices is essential to reduce the patient's physical/psychological pain and financial burden. Although wireless communication plays a critical role in implantable biomedical devices that contain the function of data transmitting, it has never been integrated with in vivo piezoelectric self-powered system due to its high-level power consumption (microwatt-scale). Here, wireless communication, which is essential for a ubiquitous healthcare system, is successfully driven with in vivo energy harvesting enabled by high-performance single-crystalline (1 − x)Pb(Mg1/3Nb2/3)O3−( x)Pb(Zr,Ti)O3 (PMN-PZT). The PMN-PZT energy harvester generates an open-circuit voltage of 17.8 V and a short-circuit current of 1.74 µA from porcine heartbeats, which are greater by a factor of 4.45 and 17.5 than those of previously reported in vivo piezoelectric energy harvesting. The energy harvester exhibits excellent biocompatibility, which implies the possibility for applying the device to biomedical applications. [ABSTRACT FROM AUTHOR]

Resistive random access memory (ReRAM) devices powered by piezoelectric nanogenerators (NGs) have been investigated for their application to future implantable biomedical devices. Biocompatible (Na0.5K0.5)NbO3 (NKN) films that are grown at 300 °C on TiN/SiO2/Si and flexible TiN/Polyimide (TiN-PI) substrates are used for ReRAM and NGs, respectively. These NKN films have an amorphous phase containing NKN nanocrystals with a size of 5.0 nm. NKN ReRAM devices exhibit typical bipolar switching behavior that can be explained by the formation and rupture of oxygen-vacancy filaments. They have good ReRAM properties such as a large ratio of RHRS to RLRS as well as high reliability. The NKN film grown on flexible TiN-PI substrate exhibits a high piezoelectric strain constant of 50 pm V−1. The NKN NG has a large open-circuit output voltage of 2.0 V and a short-circuit output current of 40 nA, which are sufficient to drive NKN ReRAM devices. Stable switching properties with a large ON/OFF ratio of 102 are obtained from NKN ReRAM driven by NKN NG. [ABSTRACT FROM AUTHOR]

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

The first direct-current triboelectric generator (DC-TEG) based on sliding electrification for harvesting mechanical energy from rotational motion is reported. The DC-TEG consists of two rotating wheels and one belt for connecting them, which are made of distinctly different triboelectric materials with a specific requirement. During the rotation, the contact-induced electrification and the relative sliding between the two wheels and the belt can induce a continuous increase of the accumulated positive and negative triboelectric charges at the two rotating wheels, respectively, resulting in a Corona discharge and producing the observed current through an external load. The DC-TEG can deliver an open-circuit voltage of larger than 3200 V and a maximum power of 100 μW under an external load of 60 MΩ at a rotational speed of 1000 r min-1. By designing a point metal discharge electrode near the accumulated positive charges on the metal wheel, the instantaneous short-circuit current can be up to 0.37 mA. The DC-TEG can be utilized as a direct power source to light up 1020 serially connected commercial light-emitting diodes (LEDs) and the produced energy can also be stored in a capacitor for other uses. This work presents a DC-TEG technology to harvest mechanical energy from rotational motion for self-powered electronics. [ABSTRACT FROM AUTHOR]

Harvesting the available forms of energies in the environment to create self-powered nanosystems is now becoming a technological reality. Self-powered nanodevices and nanosystems are expected to play a crucial role in the future development of nanotechnology because of their specific role in fundamental studies and nanotechnological applications, mainly due to their size-dependent properties and independent, sustainable, maintainance-free operation. As a new field in self-powered nanotechnology-related research, self-powered photodetectors have been developed which exhibit a much faster photoresponse and higher photosensitivity than the conventional photoconductor-based photodetectors. Herein, the energy-havesting techniques are discussed and their prospects for application in self-powered photodetectors are summarized. Moreover, potential future directions of this research area are highlighted. [ABSTRACT FROM AUTHOR]

Ultrathin piezoelectric nanogenerator (NG) with a total thickness of ≈16 μm is fabricated as an active or self-powered sensor for monitoring local deformation on a human skin. The NG was based on an anodic aluminum oxide (AAO) as an insulating layer grown on a thin Al foil by anodization, on which a thin film made of aligned ZnO nanowire compacted arrays is grown by solution chemistry. The performance of the NG is characterized with the assistance of the finite element method (FEM) simulation. The extremely thin NG is attached on the surface of an eyelid, and its output voltage/current characterizes the motion of the eye ball underneath. Since there is no external power needed for the operation of the NG, this self-powered or active sensor can be effective in monitoring sleeping behavior, brain activities, and spirit status of a person as well as any biological associated skin deformation. [ABSTRACT FROM AUTHOR]

Health monitoring helps prevent, diagnose, and treat diseases, and has been given more and more attention in recent years. Triboelectric nanogenerators (TENGs) are promising for applications in health monitoring due to their myriad of merits including low cost, simple fabrication, light weight, self‐powered property, and wide selection of materials. Here, the recent key research achievements in TENG‐based health monitoring are comprehensively reviewed. TENGs have been applied to detect not only motion‐based health conditions such as pulse and heartbeat but also nonmotion‐based health conditions such as CO2 concentration and lactate concentration. The design of device structure, sensing mechanism, device performance, advantages and disadvantages of each kind of TENG‐based health monitors are discussed. Based on recent progresses, the existing challenges and future prospects for TENG‐based health monitoring are also discussed and summarized. [ABSTRACT FROM AUTHOR]

With the arrival of intelligent terminals, tactile sensors which are capable of sensing various external physical stimuli are considered among the most vital devices for the next generation of smart electronics. To create a self‐powered tactile sensor system that can function sustainably and continuously without an external power source is of crucial significance. An overview of the development in self‐powered tactile sensor array system based on the triboelectric effect is systematically presented. The combination of multi‐functionalization and high performance of tactile sensors aimed at achieving highly comprehensive performance is presented. For the tactile sensor unit, a development is summarized based on the two primary modes which are vertical contact–separation and single‐electrode. For the pressure mapping array, the resolution is significantly enhanced by the novel cross‐type configuration based on the single‐electrode mode. Integrated with other mechanisms, the performance will be further elevated by broadening of the detect range and realizing of visualization of pressure imaging. Then, two main applications of human–machine interaction (HMI) and trajectory monitoring are comprehensively summarized. Finally, the future perspectives of self‐powered tactile sensor system based on triboelectric effect are discussed. [ABSTRACT FROM AUTHOR]

On page 5211, S. Nahm and co‐workers present a resistive random access memory (ReRAM) driven by a piezoelectric nanogenerator (NG). Biocompatible (Na0.5K0.5)NbO3 lead‐free piezoelectric thin films were used for both ReRAM and NG. The NKN ReRAM powered by NKN NG shows a stable memory performance, which can be applied to various advanced self‐powered biomedical systems. [ABSTRACT FROM AUTHOR]