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[Display omitted] • High triboelectric output voltage (310 V) and power density (6.14 W/m2); • Nano perovskite was dispersed in rubber uniformly by a simple way; • The TENG can be used to monitor the human behavior and driving conditions; • We can control the surface charge density by changing proportion of fillers. Flexible wearable triboelectric nanogenerator (TENG) has attracted immense interest in various application scenarios due to its intrinsic self-powered characteristics. Recently, rubbers with high elasticity are frequently reported to be favored substrates for wearable smart devices to enhance body comfort and contact effects. However, most commercial rubbers are nonpolar and lack of enough polar functional groups even after physical and chemical modification to earn satisfactory surface charge density for high triboelectric performance. Moreover, the combination of high triboelectric and mechanical properties is still a significant challenge for flexible TENG material. In this work, a flexible triboelectric rubber with tunable surface charge density and excellent mechanical properties is demonstrated via a natural polymer assisted dispersion of perovskite nanofiller strategy. The designed rubber-based TENG shows an excellent 310 V triboelectric output, 106 nC transferred charge and 6.14 W·m−2 power density, as well as a favorable mechanical property of 10.69 MPa Young's modulus and 211 % strain. The material can harvest mechanical energy and charge 1 μF commercial capacitors to 1.8 V in 60 s from nature. When serves as flexible device, it can also self-powered to real-time monition various human behavior and distinguish different speed of vehicle driving conditions. We expect our works will provide a feasible strategy to significantly improve the comprehensive performance of flexible wearable rubber-based TENG and advance the potential application of rubber. [ABSTRACT FROM AUTHOR]

A magnetic textile that is inspired by mussels and designed with featuring reversible wettability enables non-contact oil recovery through its sensitive response to pH changes and magnetic fields. Beyond oil spill recovery, this work delves into the domains of energy harvesting on the base of the triboelectric activity of the smart textile. It is disclosed that the asymmetric alternating electric field resulted from the triboelectric effect significantly enhances the oil–water separation efficiency. Additionally, by integrating traditional cathodic protection with TENGs that are fabricated from the magnetic textile, a multifunctional and efficient self-powered electrochemical marine conservation system is provided for intelligent environmental cleanup and sustainable marine protection. [Display omitted] • Robust magnetic textile with pH-sensitive switchable wettability was fabricated through Schiff condensation. • Magnetically controlled oil–water separation and non-contact oil recovery were demonstrated. • Triboelectric performance was both dielectrically and magnetically enhanced. • Three-dimensionally arranged TENG units enhanced the wave-direction adaptivity and wave energy collection efficiency. • TENG-driven self-powered electrochemical marine protection system was developed. Intelligent materials that are built with reversibly switchable wettability between superhydrophilicity-hydrophobicity are crucial for combating environmental challenges such as spill oil cleanup and fuel purification. In this work, inspired by mussel, a robust magnetic textile was prepared by anchoring titanium dioxide and magnetic carbon nanotubes onto textile through Schiff condensation between the amine groups of dopamine and the carboxyl groups of lauric acid. Reversibly switchable wettability was presented on the as-fabricated textile, where superhydrophobic/oleophilic could be achieved at pH 3–7 and hydrophilic/underwater oleophobic were achieved at pH 13. With a maximum saturation magnetization of 17.99 emu/g, it achieves non-contact oil spill recovery through its response to pH and magnetic fields. Interestingly, the asymmetric electric field of M−TENG accelerate the coalescence of water on fabric and oil–water mixture separation. Furthermore, the output performance of M−TENG was dielectrically and magnetically enhanced, with a power density of 0.837 W·m−2. Additionally, a self-powered marine protection system was developed by integrating cathodic protection principles with M−TENG, where the three-dimensionally accommodated triboelectric unit enhanced the efficiency for collecting wave energy, thereby protecting marine vessel components effectively. This work provides guiding strategies for developing self-powered devices for marine conservation and protection based on smart materials and TENG. [ABSTRACT FROM AUTHOR]

Self-powered sensors detect a variety of crucial parameters for industrial processes without any external power source for Industry 4.0. It has capabilities to acquire, analyze, and make decisions on real-time data, these sensors are essential for the advancement of automated production systems and smart factories. In this regard, Triboelectric nanogenerators (TENGs) have potential to provide effective solution as self-powered vibration sensor for continuous monitoring of machine tools. Different techniques have been used to enhance the performance of TENG such as material doping, chemical etching, ion injection, etc. However, laser surface texturing is a low-cost, contact less, efficient technique which can be used for improving the response of TENG-based self-powered vibration sensors. In this context, Laser Induced Backside Texturing is a laser micro texturing approach to improve the electrical performance. It induces waviness and surface roughness, which leads to increased surface charge density and triboelectrification capabilities. In this work, laser micro texturing was performed using with 405 nm wavelength semiconductor diode laser to generate line pattern texture on the Fluorinated Ethylene Propylene (FEP). Laser textures TENG (LT-TENG) was developed with laser textured FEP as tribonegative material and pristine Aluminium as tribopositive material, the open-circuit voltage, short-circuit current and power density achieved 23 %, 41 %, and 47 % enhancement respectively, generating 794 V, 44 µA, and 2371.6 µW/cm2. This increase in output leads to an increased sensitivity of the sensor. When mounted on the machines, LT-TENG was able to detect their working state, vibration frequency, and harmonics i.e. 46, 92, 184 Hz for the vacuum pump and 140, 280, 410 Hz for the heat gun. These detected vibration frequencies, and their harmonics were similar to the frequencies detected by the commercial accelerometer (CTC AC115), confirming potential use of LT-TENG as a low-frequency vibration sensor. The developed LT-TENGs was integrated with the Internet of Things (IoT) supported microcontroller, which collects real-time data for continuous monitoring and analysis for machine health monitoring in smart devices. [Display omitted] • IoT-enabled Laser Textured TENG-based Self Energizing Vibration sensor is presented. • Single Triboelectric Nanogenerator acts as energy harvester and vibration sensor. • Laser Textured TENG have shown notable 41 % enhancement in current. • Laser Textured TENG improves the sensitivity towards vibration sensing. [ABSTRACT FROM AUTHOR]

• Non-centrosymmetric hexagonal SnS 2 nanoparticles with a band gap of 2.4 eV were synthesized via a hydrothermal route. • Nanogenerator was fabricated by sandwiching the PVDF-SnS 2 composite between ITO-coated substrates with external contacts drawn using silver paste. • The open-circuit voltage of nanogenerator is 24.4 V, at dark conditions, which increases to 72.9 V upon illumination, with short-circuit current of 0.75 µA. • The superior response is attributed to the excellent photo absorption properties of SnS 2 and PVDF-SnS 2 interfacial polarization. Piezoelectric nanogenerators (PENGs) can power microelectronics, which convert weak mechanical vibrations to electrical impulses; however, low output voltage and poor mechanical durability limit PENG use. Thus, we provide photoactive SnS 2 nanofillers in a PVDF matrix for piezoelectric nanogenerators (PPENGs). Raman spectroscopy demonstrates improvement of the electroactive β-phase of PVDF due to adding photoactive hexagonal SnS 2 nanoparticles with a band gap of 2.4 eV. Sandwiching the PVDF-SnS 2 composite between ITO-coated substrates with silver paste contacts fabricated the PPENG. The open-circuit voltage of PPENG is 24.4 V in the dark and 72.9 V under illumination with a short-circuit current of 0.75 μA, showing its outstanding photo responsiveness. The high light absorption of SnS 2 and PVDF-SnS 2 interfacial polarization caused the improved response. High-performance optoelectronic and energy harvesting applications may employ this photoactive piezoelectric nanogenerator development technique. [Display omitted] [ABSTRACT FROM AUTHOR]

• A novel low potential energy barrier bistable jellyfish-inspired oscillator is proposed. • A low-frequency broadband jellyfish-inspired bistable piezoelectric-triboelectric hybrid generator is designed. • The impact of parameters on the mechanical properties of the bistable system is analyzed. • An electromechanical coupling model incorporating triboelectric and piezoelectric mechanisms is established. • The high output performance of the generator in terms of low-frequency broadband is confirmed by the experiment. In pursuit of enhancing the output power of energy harvesters, this paper introduces a novel jellyfish-inspired bistable piezoelectric-triboelectric hybrid generator (JIB-PTHG) with low potential energy barrier characteristics and low-frequency, broadband energy harvesting capabilities. The JIB-PTHG comprises two flexible beams, and two rigid links, connected via a spring. Utilizing the harmonic balance method and Runge-Kutta fourth-order algorithm, a comprehensive analysis of the mechanical properties of the low-barrier bistable structure is conducted. Static equilibrium bifurcation and dynamic response analysis are performed. Subsequently, an electromechanical coupling model incorporating piezoelectricity and triboelectricity is developed to theoretically predict the output voltage of the two modules, revealing a positive correlation between displacement and output voltage. Experiment validation demonstrated that adjusting the length of the rigid links can effectively increase the deformation of the piezoelectric beam and the relative displacement of the triboelectric layers, thus improving the generator's output performance. Specifically, the TENG module exhibited exceptional energy harvesting performance within the frequency range of 3.5–6.5 Hz, achieving a voltage of 1050 V, a power of 1.84 mW, and the ability to illuminate 70 LED lights under an excitation amplitude of 17.5 mm and a frequency of 5.5 Hz. The PEG module, displayed high output performance within the frequency range of 4-7 Hz, reaching a voltage of 6.2 Vs and a power of 12.8 μW at an excitation frequency of 7 Hz and an amplitude of 17.5 mm. Both theoretical and experimental findings indicate that the JIB-PTHG has achieved improved output power within the frequency range of 3.5–6.5 Hz. Furthermore, the JIB-PTHG has the potential to harness bridge vibration energy and convert it into useful electrical energy for powering wireless sensor nodes in bridge health monitoring systems. [Display omitted] [ABSTRACT FROM AUTHOR]

The triboelectric-electromagnetic hybrid nanogenerator (TEHG) is a prospective wave energy generation technology that directly transform low-frequency kinetic energy into electrical energy. This paper proposes a tubular liquid-solid-triboelectric-electromagnetic hybrid nanogenerator (TLS-TEHG) that efficiently collect wave energy and drive ocean sensors. The innovative design of the generator structure ensures high integration between the electromagnetic generator (EMG) and the liquid-solid tubular triboelectric nanogenerator (LST-TENG). The magnetic sphere string length and the magnetic sphere diameter have a positive effect on the TLS-TEHG performance. TLS-TEHG combines the advantages of the LST-TENG and EMG, with the LST-TENG delivering 75 V, 8.8 μW, and a current density of 0.0009 μA/cm2 at a frequency of 0.5 Hz, and the EMG delivering 0.3 V, 2.35 mW, and a current density of 16,858.8 mA/cm2 at a frequency of 1.2 Hz. The TLS-TEHG can charge a 3.3F capacitor to 12 V and power ocean temperature sensors and LED illumination even at low frequencies (0.5 Hz). This research provides valuable technological support for enhancing wave energy harvesting efficiency, validating potential applications in wave energy harvest and self-powering of ocean sensors. [Display omitted] • TLS-TEHG's power output can be enhanced by innovatively combining LST-TENG and EMG, which complete each other. • Substantially broadband wave energy harvesting in higher energy density. • The LST-TENG output reaches 75 V, 8.8 μW, whereas the EMG output reaches 0.3 V, 2.35 mW. • Offering valuable instruction for the development of high-efficiency wave energy harvesting devices. [ABSTRACT FROM AUTHOR]

[Display omitted] • A piezo-tribo hybrid nanogenerator (PTNG) based on polytetrafluoroethylene-polyvinylidene fluoride/Ti 3 C 2 T x was proposed for self-powered ammonia sensors. • Through the synergistic enhancement of piezoelectric and triboelectric effects, the output voltage of the PTNG reached 200 V, ensuring stable power supply for self-powered ammonia sensors. • A PTNG-based PANI/ZnO heterostructure self-powered ammonia sensor was constructed, with the low detection limit of 0.1 ppm, enabling self-powered detection of low-concentration ammonia gas. Self-powered sensors are receiving increasing attention for their environmental friendliness and energy efficiency. In this work, self-powered polyaniline/zinc oxide (PANI/ZnO) heterostructure-based ammonia (NH 3) sensor was driven by polytetrafluoroethylene (PTFE)-polyvinylidene fluoride/Ti 3 C 2 T x (PVDF/MXene) piezo-tribo hybrid nanogenerator (PTNG) at room temperature. PVDF/MXene nanofiber membranes were prepared using electrospinning technology to construct a PTFE-PVDF/MXene PTNG. This enhances the effective contact area and dielectric properties of the composite film, thereby increasing the surface charge density. Additionally, the synergy between the triboelectric and piezoelectric effects significantly improves the output performance of the PTNG, effectively enabling energy harvesting for wearable devices. In addition, ZnO/PANI composite materials with a large specific surface area and high active sites were prepared, and a self-powered ammonia sensor was constructed based on the impedance matching effect. Furthermore, by constructing a PANI/ZnO p-n heterojunction, the number of active sites has been increased, significantly enhancing the sensing performance. The sensor has a minimum detection limit of 0.1 ppm, and at an NH 3 concentration of 10 ppm, the response rate reaches 96.1 %. This study provides insights for the development of self-powered gas detection systems and holds significant research and practical value in enhancing the performance of NH 3 sensors. [ABSTRACT FROM AUTHOR]

[Display omitted] • Self-powered visible light CdSe/Si photodetector. • Pronounced spectral response at 575 nm. • Rapid rise/fall periods of 0.31 and 0.34 sec. • Time-resolved based power dependency indicated linear correlation at 0 bias. Self-powered visible light photodetector based nanostructured CdSe/Si geometry was fabricated using pulsed laser deposition (PLD). Herein, a detailed microstructural investigation was demonstrated in conjunction with the overall device photoresponsive performance. Particularly, an average particle diameter of 66.62 nm along optical band gap of 2.25 eV were attained. This was, subsequently, perceived in the fabricated device spectral response performance during which photocurrent (I ph ) of 47 µA was attained under incident light of 575 nm and 6 mW / cm 2 , the nearest incident wavelength to the obtained optical band gap. At the reported incident light features, the proposed arrangement exhibited responsivity (R λ) of 7.85 mA / W with light to dark current ratio (I ph / I D) of 998 %, respectively. Herein, the incident power variation suggested a linear increment ( R 2 ≈ 0.94) in both I ph and I ph / I D profiles, with values of 71 µA and 1501 %, respectively, at 575 nm and 26 mW / cm 2. The fabricated device exhibited a pronounced time-resolved feature with rise/fall periods of 0.31 and 0.34 sec., while the power dependance based time-resolved behavior indicated a linear correlation between the stated factors with R 2 value of 0.924, both of which were carried out at 0 bias voltage. The dual-singularity evidenced the self-powered feature of the proposed photodetector, where zero external potential is required. [ABSTRACT FROM AUTHOR]

This study introduces a novel self-powered metamaterial augmented nanogenerator for low-frequency acoustic telecommunication (MANLAT), which is designed to enhance acoustic communication capabilities by utilizing the local resonance mechanism to selectively amplify specific frequency bands of incident sound and generate large amplitude signals in a self-powered manner. The MANLAT device consists of a flexible bottom that responds to pressure differences by generating strong vibrations. Additionally, a lightweight cone-shaped component is attached to the central part of the flexible plate, thus increasing the surface area in that region. Through contact electrification and electrostatic induction mechanisms, a substantial electrical signal is generated, allowing the device to serve as a self-powered acoustic telecommunication receiver. To assess its performance in real-world scenarios, environmental interference was simulated by generating white noise added to the modulated waveform containing information, which was then transmitted through a loudspeaker. At the receiving end, a high-precision microphone sensor was used alongside the MANLAT device to capture the sound wave. The experimental results demonstrate that the MANLAT device surpassed the microphone sensor in mitigating noise interference and enabled the effective decoding of information even in the presence of high levels of white noise or background music. Consequently, the device simplifies communication systems, facilitates reliable and environmentally friendly communication, and enhances information security. [Display omitted] • A self-powered low frequency acoustic telecommunication device is proposed. • The device shows strong anti-interference capability. • Covert communication is demonstrated with background music. [ABSTRACT FROM AUTHOR]

Van der Waals and wide-bandgap materials-based heterostructures have garnered substantial attention in developing self-powered broadband photodetectors owing to their exceptional photovoltaic capabilities. These materials also hold great potential for breakthroughs in optoelectronics. However, limitations to low selectivity constrain the potential of heterostructures-based broadband detectors. Here, we design wavelength-selective polarity switching in a heterostructure photodetector consisting of bismuth selenide (Bi 2 Se 3) and gallium nitride (GaN). The analysis revealed a positive photocurrent under ultraviolet-C illumination to visible wavelength, whereas a negative photocurrent under infrared wavelengths at zero applied bias. The exposure to distinct optical wavelengths leads to an inversion in the electric field polarity across the junction, resulting in polarity switching. The fabricated Bi 2 Se 3 /GaN self-powered ultra-broadband photonic device demonstrates a peak photoresponsivity of 584 mAW−1 (−297 mAW−1) at 355 nm (1405 nm) wavelength illumination and can detect weak signals up to 650 femto-watt. Our strategy revealed alternative avenues for developing polarity-switchable, self-powered ultra-broadband photodetectors, offering a first step towards creating wavelength-adaptable sensors for future applications. [Display omitted] • Novel self-powered photodetector using a heterostructure of Bi 2 Se 3 and GaN. • Wavelength-selective polarity switching (Deep UV to IR) self powered photodetector. • Exhibits a peak photoresponsivity of 584 mAW−1 @ 355 nm & −297 mAW−1 @ 1405 nm under self-powered mode. • Dedetect weak optical signals as low as 650 femto-watt. [ABSTRACT FROM AUTHOR]

Tactile sensors play a critical role in the Internet of Things (IoT) and wearable devices. However, although current tactile sensors can precisely measure pressure, the simple fabrication of stretchable high-performance tactile sensors with a broad measuring range and multifunctions is still challenging. Herein, an ink-direct writing 3D printing method is developed to fabricate novel stretchable dual-mode tactile sensors with coaxial fiber structure. The 3D printed coaxial fibers have an outer skin composed of silicone rubber and polytetrafluoroethylene micropowders thixotropic agent and an inner core of an ionic conductive solution composed of polyvinyl alcohol and sodium chloride. The coaxial fibers exhibit excellent electrical conductivity (0.54 S cm−1) and outstanding stretchability, as high as 390 %. The intersection of the two fibers constitutes a dual-mode tactile sensor which can operate in triboelectric or capacitive modes with complementary measurement ranges from 0.0003 to 0.4517 N. Besides, by combining the signals from the two modes, the sensor can identify the material that comes into contact with the sensor. A 3D printed network of tactile sensor arrays made of warp-weft interwoven coaxial fibers is able to accurately detect the locations of multi-point contact with the array. This dual-mode multifunctional tactile sensor can be widely used in various applications such as the IoT and wearable devices. [Display omitted] • An ink-direct writing 3D printing method is developed to fabricate stretchable dual-mode tactile sensors.. • The coaxial fibers showed high conductivity (0.54 S cm−1) and stretchability (390 %). • The tactile sensor can identify the material by combining the signals from the triboelectric and capacitive modes. • A 3D printed network of tactile sensor arrays is able to accurately detect the locations of multipoint contact. [ABSTRACT FROM AUTHOR]

Triboelectric nanogenerators (TENGs) have aroused extensive interests in recent years, and their energy conversion efficiency increased gradually under massive efforts. Applied force and dielectric thickness are two important factors accounting for the high output performance. Nevertheless, for the most commonly used TENGs in the contact-separation mode, the comprehensive dependence of dielectric thickness and impact force is still expected to be further deeply researched and optimized. Hence, we fabricated a nylon-PTFE TENG in the contact-separation mode and explored the dual influence of dielectric thickness and applied force on the output performance. The results indicate that the dielectric thickness and the magnitude of force have a comprehensive influence on the outputs, which is due to the dual effect of charge transport properties and the microcosmic deformation at different thicknesses. In general, the optimum thickness increases from 0.5 mm to 0.7 mm obviously as the force magnitude increases from 15 N to 60 N, but stays steadily with varying fabric count. With the continuous enlargement of impact force, the dielectric thickness reaches a boundary limitation of 0.8 mm. This work contributes greatly not only to the design and optimization of TENG devices, but also to the deeper understanding of the nano-triboelectric effect mechanism. [ABSTRACT FROM AUTHOR]

Despite its long history and importance in many areas of science and technology, there is no agreement on the mechanisms responsible for tribo-electric charging, including especially the tribo-charging of chemically identical dielectric solids. Modeling of the excitation, diffusional transport, and de-excitation of electrons from hot spots shows that a difference in local surface roughness of otherwise identical solid dielectric objects leads to different transient excited electron concentrations during tribo-processes. The model predicts that excited electron concentrations are lower and concentration gradients higher in solids with rougher rather than smoother surfaces. Consequently, during contact, the flux of charge carriers (electrons or holes) from hot spots will be greater into the rougher solid than into the smoother solid. These predictions are in agreement with current and historical observations of tribo-electric charge transfer between solids of the same composition. This effect can take place in parallel with other processes and may also play a role in the charging of solids of different composition. [ABSTRACT FROM AUTHOR]

Triboelectric nanogenerator (TENG), which converts mechanical energy into electrical energy, has become a promising environment energy harvesting technology. However, traditional TENG, based on the coupling of contact electrification and electrostatic induction, generates alternating current (AC) directly, which requires a rectifier to obtain direct current (DC) before being used to drive electronics. There are a few methods to obtain DC output including mechanical rectifier, phase coupling, air breakdown, and Schottky contact. But to achieve high output and high durability of DC‐TENG, new exploration is desired. In this study, a novel DC‐TENG is proposed, which greatly improves the output performance by designing a mechanical time‐delay switch and an alternative blank‐tribo‐area. The working mechanism of the DC‐TENG is analyzed theoretically and verified by experiments. It is found that the blank‐tribo‐area promotes charge accumulation, while the mechanical time‐delay switch realizes DC output. This DC‐TENG can light up 1888 LEDs in series at 60 rpm and drive 24 hygro‐thermographs in parallel with 120 rpm. The ultra‐high average power density of 4.2 W m−2 is achieved, much higher than previous works. The DC‐TENG displays high durability and retains 92% initial output after 120 000 cycles. This st provides a feasible strategy to boost the output performance of DC‐TENG. [ABSTRACT FROM AUTHOR]

Pyro/piezoelectric effects are thought as essential ways to modulate photoresponses of optoelectronic devices, but the pyro/piezoelectric materials usually function as photoactive or fundamental band matching layers. In this manuscript, a Cu(In,Ga)Se2 (CIGS) multilayer heterojunction of Glass/Mo/CIGS/CdS/ZnO nanowire/ITO is prepared as a self‐powered photodetector (PD). The PD exhibits excellent performances in 405 to 1064 nm with maximum responsivity (R) of 0.455 A W−1, and detectivity (D) of 7.22 × 1011 Jones at zero bias. More importantly, the temperature variation‐induced pyroelectric field in the non‐photoactive ZnO layer is demonstrated to facilitate the transport of carriers. After introducing the pyroelectric effect, the responsivity (R) and detectivity (D) are largely increased to 4.92 A W−1 and 7.81 × 1012 Jones, respectively, and an ultrafast response time of 67.13/78.57 µs is obtained. Meanwhile, the response wavelength is extended to 1550 nm, which is far beyond the spectral limitation of the heterojunction. Besides, the piezoelectric effect of the ZnO nanowire can further optimize the band alignment and then boost the photovoltaic and pyroelectric responses. Owning to the favorable three‐synergistic mechanisms, the best R of 7.22 A W−1 and D of 1.17 × 1013 Jones are observed, which are enhanced by 1586.8% and 1620.5%, respectively, and the response time is also shortened to 50.17/60.65 µs. [ABSTRACT FROM AUTHOR]

Due to the advantages of natural softness and flexibility of water, liquid–solid‐based triboelectric nanogenerators (TENGs) have aroused wide attention recently and much effort has been devoted to improving its output performance. Herein, the performance of liquid–solid‐based TENG is greatly improved through two simple steps. First, an end electrode is added into the traditional tube‐based TENG and the volume effect is successfully realized, with the output voltage improved by ≈40 times to 240 V. Then, the output voltage of the tube‐based TENG can be further improved to 461 V by replacing water with NaOH solution and an impressive peak power density of 1910 Wm−3 and an average power density of 459 Wm−3 can be achieved. Additionally, the demonstration shows that the solution‐tube‐based volume effect TENG can work well at various operation modes and generate power from multiple mechanical energy sources. In addition to wearable human motion energy recovery, wave energy recovery, and electrochemical cathodic protection systems, the device also shows its application potential in biochemical sensing based on the solute concentration‐dependent output signal. [ABSTRACT FROM AUTHOR]

Electronic skins (e‐skins) mimic multimodal sensing capabilities of various tactile receptors in natural skin. Herein, a stretchable chromotropic ionic skin is rationally designed to simultaneously detect and decouple multiple stimuli, including in‐plane strain, temperature, and pressure. The mutually discriminating trimodal ionic skin consists of mechanochromic, thermoresistive and triboelectric layers that individually function as strain, temperature and pressure sensors, respectively. These three distinct capabilities are integrated into the ionic skin which demonstrates highly sensitive responses to selective external stimuli while upholding high insensitivity to unwanted ones. The structural colors derived from mechanochromic photonic crystals of magnetic ferroferric oxide‐carbon nanoparticles respond to strains by color‐switching in the full visible spectrum, exhibiting appealing potential in interactive stress visualization. The temperature detection with an exceptional sensitivity of 20.44% per °C is enabled by the thermoresistive effect of ionic hydrogel, while oriented polymer chains embedded in the hydrogel decouple temperature from extraneous stimuli. The multilayer structure consisting of an ionic hydrogel film, a wrinkle‐patterned polydimethylsiloxane (PDMS) film with gradient modulus design and a carbon nanotubes/PDMS electrode displays an extraordinary triboelectric effect with a strain‐ and temperature‐insensitive pressure sensing capability. The chromotropic ionic skin facilitates simultaneously accurate measurements, high discriminability and quantitative mapping of complex stimuli, offering new insights into emerging E‐skins. [ABSTRACT FROM AUTHOR]

Power management circuit (PMC) can efficiently store the output energy of pulsed triboelectric nanogenerator (Pulsed-TENG). Unidirectional current Pulsed-TENG (UP-TENG) has the advantage of without using rectifier bridge. However, the energy storage efficiency is limited for large capacitors at low capacitor voltage (<10 V). To solve this problem, PMC is optimized here. Firstly, rectifier diode is used to reduce the energy loss. Energy storage efficiency of PMC using rectifier diode (D-PMC) is higher than that of conventional PMC. Then, appropriate inductor is used to further form the optimized PMC (O-PMC), which reduces the energy loss of inductor. Results show that O-PMC using 100 ÎĽ H inductor has the highest energy storage efficiency. The actual test energy storage efficiency of O-PMC is 30.6%, which 3.4 times higher than that of D-PMC. Finally, an external capacitor is connected to electrodes of UP-TENG to form the EUP-TENG, which improves charging speed and output voltage of O-PMC. O-PMC using EUP-TENG can stably power calculator at low motion frequencies. O-PMC can be widely used in self-powered systems. [ABSTRACT FROM AUTHOR]

Electrostatic separation processes are emerging as the solution of choice for recycling waste from end-of-life equipment in various industries. The separation of the different constituents of such plastic mixtures is the key to successful recycling. The main objective of this work was the development of a new spiral-type tribocharging device with application in the field of electrostatic separation. The spiral charger offers a very high charging rate compared to other triboelectric systems. It favors collisions of the particles with the inner wall, which is very efficient to separate a mixture of ternary particles. The study was conducted with samples of various medium-sized (2–5 mm) granular plastics, for several values of air velocity, pipe length, and particle mass in the turbocharging device. The spiral charger was associated with a belt-type electrostatic separator to process a granular insulating mixture, consisting of three types of plastic products Polyvinyl Chloride, Polypropylene, and Polystyrene. This work also aims at numerically simulating the dynamic behavior of insulating particles in belt-type electrostatic separators. The good separation obtained for this ternary mixture shows the efficiency of the new tribocharger. [ABSTRACT FROM AUTHOR]

Electrostatic separation is able to process mixtures of plastics from waste electrical and electronic equipment. The efficiency of the electrostatic separation depends on the electric charge acquired by the particles in the appropriate tribocharging devices. The aim of this work is to validate the possibility of using a roll-type electrostatic separator to sort mixtures of particles that are difficult to process by other means. In this type of separator, the plastic particles are charged by triboelectric effect. Two types of charging devices have been used: fluidized bed and rotating multicylinder. Two series of experiments were performed with samples composed in equal proportions of: first, acrylonitrile butadiene styrene (ABS) and polystyrene (PS); second, polypropylene (PP) and polyethylene (PE). A third series of experiments were carried out with a mixture of three plastics: PP, PE, and ABS, and the last series of experiments were carried out with a mixture of four plastics of (PE/PP/ABS/PS), with an average particle diameter ranging between 3 and 6 mm. The efficiency of the electrostatic separation was evaluated by measuring the charge, purity, and recovery of the granules collected at the outlet of the electrostatic separation. The results confirm that the separation of ABS/PS and PP/PE mixtures is feasible and the best separation results were obtained using the fluidized bed tribocharger. [ABSTRACT FROM AUTHOR]

A self‐rebounded hybrid energy harvester from human foot motion is investigated. The hybrid energy harvester integrates electromagnetic generators (EMG), piezoelectric nanogenerators (PENG), and triboelectric nanogenerators (TENG) between the two magnetic poles. The harvester uses a pair of mutually exclusive magnetic poles instead of spring‐mass to realize reciprocating motion, which is designed to grow 6 cm, width 5 cm, and height 4 cm. Under low frequency (4 Hz), EMG, PENG, and TENG can deliver a high output power of 6.49 mW, 0.168 µW, and 90.72 µW, respectively. After charging the energy harvesting circuit, the capacitor can continuously output a stable 5 V DC voltage, and the charging performance of the harvester is better than that of a single nanogenerator unit. Besides, the harvester can continuously light up 80 LED lights. After carrying the harvester and jogging for a certain distance, a pedometer module is powered. It shows that the designed self‐rebounding human motion foot energy harvester has certain feasibility in the practical application of wearable devices. The device can be easily assembled under the shoes, demonstrating the great application prospects of the harvester as a sustainable self‐power device for wearable and portable electronics. [ABSTRACT FROM AUTHOR]

Measurement while drilling (MWD) system of offshore drill pipe is of great significance for safety production. It is greatly demanded to develop a sustainable power supply as well as self‐powered sensors for the MWD system. In this work, a drill pipe‐embedded annular type triboelectric nanogenerator (AT‐TENG) is proposed and systematically investigated, and it consists of an annular silicone rubber and a pair of electrodes. The design of the AT‐TENG allows the silicone rubber to contact and separate with the electrodes easily in a narrow space under arbitrary direction vibration to realize power generation. The experimental results show that the peak power density of AT‐TENG with single‐pair electrode reaches 63.7 W m−3 under the vibration frequency of 4 Hz and amplitude of 100 mm. The minimum peak voltage is >65 V within 360° lateral vibration range. The peak voltage achieves 351.62 V under the third‐order natural frequency. In addition, the amplitude and frequency obtained from the voltage signals exhibit linearly with those of actual vibration. The mean error between the frequency detected by AT‐TENG and actual frequency is <0.03%. Thus, the AT‐TENG can serve as an energy harvester and self‐powered vibration sensor. [ABSTRACT FROM AUTHOR]

Rietveld refinement techniques have been used to investigate the structural characteristics of CdS window layers at various thicknesses in the current study. The structural parameters were improved as the thickness of the CdS-layer was raised, according to XRD patterns. This, in turn, was owing to the increase in the crystal's size for the studied thin layers. For the Ni/n-CdS/i-AgSe/p-CdTe/Pt heterojunction that was successfully fabricated employing an AgSe buffer layer deposited directly on the p-CdTe absorber layer and then the CdS window layer deposited on these mentioned layers, the photovoltaic properties were determined under the dark and illuminated conditions. In dark conditions, from the forward and reverse (current-voltage) data, the essential behavior related to the fabricated devices has been determined. In addition, the heterojunction resistance, the shunt resistance, the series resistance and the rectification rate were all determined. As well, in the illumination case, the open-circuit voltage, the short-circuit current, the fill factor, the power conversion efficiency, (PCE), the photoresponsivity, the quantum efficiency, the dependence of generated photocurrent on the light intensity, the dependence of generated photocurrent on wavelength (λ) for the studied solar cells have been computed and discussed. [ABSTRACT FROM AUTHOR]

Summary: The new field of applications for triboelectric materials is based on the combination of high physical durability and charge properties of ZnO semi‐conductor thin films, which have been explored in this work. ZnO films are successfully deposited by the RF magnetron sputtering method in the wurtzite phase. A post‐heat‐treatment process of the as‐deposited films is carried out in an oxygen atmosphere at 973 K. According to the X‐ray diffraction patterns, scanning electron microscope (SEM), and atomic force microscopy (AFM) images, the average particle size of the ZnO films increases gradually with the heat‐treatment process. The semilogarithmic current‐voltage and frequency‐dependent capacitance measurements of thin films under various bias voltages are done to understand the charge transfer resistance, conductivity and capacitance properties which directly affect the figure of merit (FOMm) of the triboelectric layer material performance. The charge density and triboelectric charge density values in present study for heat‐treated thin films are 11 and 121 mC/m2, respectively. These findings might be used as a good candidate for further triboelectric device energy research areas in the near future. [ABSTRACT FROM AUTHOR]

The enrichment of vitrinite can enhance the oil yield and conversion rate in low-rank coal liquefaction. The work evaluated the effects of surface modification on the rotary triboelectric separation of macerals. Permittivity and charge–mass ratio analysis of vitrinite and inertinite under various modified conditions demonstrated that kerosene and diesel were excellent modifiers since they keep the permittivity of macerals at a low level. The largest difference in triboelectric charge of vitrinite and inertinite was obtained when 3.0 kg/t kerosene was adopted as modifier. Rotary triboelectric separation of untreated low-rank coal indicated that the optimal separation, i.e., a vitrinite content of 65.45% and a recovery of 69.89%, was obtained at a feed rate of 1.5 g/s, a friction wheel speed of 3000 rpm, and a separation voltage of 30 kV. Under the optimum operating conditions, the optimal rotary triboelectric separation under surface modification, i.e., a vitrinite content of 69.78% and a recovery of 73.52%, was achieved when the coal was treated by 3.0 kg/t kerosene. The results demonstrated that surface modification significantly improved the rotary triboelectric separation by changing the surface electrical properties of macerals, while the excessive dosage of the modified reagent was unfavorable to achieving optimal separation. [ABSTRACT FROM AUTHOR]

Photodetectors generally operate exclusively in either the broadband or narrowband. Developing bifunctional photodetectors that can detect photons in both broadband and narrowband would bring significant versatility to the optoelectronic platform. Nevertheless, the design of bifunctional integrated devices remains challenging due to the differentiated strategies with respect to device structure and material combination. Herein, we propose introducing polyvinylpyrrolidone to increase the viscosity of the perovskite precursor solution, which introduces abundant defects and cavities into the perovskite film while maintaining a relatively low film thickness. Then, we use methylamine gas to postprocess the middle area of the film to promote directional recrystallization and densification, thereby realizing narrowband and broadband dual‐function photodetection in a single device at zero bias. Both ends of the film exhibit a near‐infrared peak response at 780 nm with a narrow full‐width at half maximum of approximately 30 nm without an external bias. The middle broadband photodetector exhibits a high responsivity of 329 mA W−1 and EQE up to 52.46% at 780 nm. We make full use of narrow‐band wavelength selective detection and broadband full‐spectrum detection to achieve double encryption during signal transmission. This work represents an important step toward the realization of perovskite‐based multifunctional integrated devices. [ABSTRACT FROM AUTHOR]

High-performance, wearable, and self-powered mechanical sensors for human health monitoring, motion detection systems, and human–machine interfaces are attracting attention owing to the increased interest in green energy. Piezoelectric and triboelectric effects are being exploited to develop various types of self-powered mechanical sensors; however, unresolved issues such as complicated processes and limitations in material selection and practical applications remain. A type of effective self-powered mechanical sensor based on the hybrid triboelectric–flexoelectric effect of multilayered MoS2 hollow spheres is reported herein. This triboelectric–flexoelectric mechanical sensor (TFMS) exhibits superior sensing characteristics, including wide-range pressure detection and superior stability, owing to the remarkable hybrid triboelectric–flexoelectric effect of optimized MoS2 hollow spheres under stress. In addition, the operating mechanism of the fabricated TFMS is discussed based on the size and number of the multilayered MoS2 spheres using finite element method (FEM) simulations of the effective stress under pressure changes. Furthermore, the effective operation of the sensor in detecting various human physiological motions from the wrist pulse to walking/running is demonstrated. These results are expected to promote the development of advanced mechanical sensors for applications such as next-generation prostheses and human–machine interfaces. [ABSTRACT FROM AUTHOR]

Triboelectric nanogenerators (TENGs) based on sliding silicon–organic monolayer–metal Schottky diodes are an emerging autonomous direct-current (DC) current supply technology. Herein, using conductive atomic force microscopy and electrochemical techniques, we explore the optimal etching conditions toward the preparation of DC TENGs on Si(211), a readily available, highly conductive, and underexplored silicon crystallographic cut. We report optimized conditions for the chemical etching of Si(211) surfaces with subnanometer root-mean-square roughness, explore Si(211) chemical passivation, and unveil a relationship between the electrochemical charge-transfer behavior at the silicon–liquid interface and the zero-applied bias current output from the corresponding dynamic silicon–organic monolayer–platinum system. The overall aim is to optimize the etching and functionalization of the relatively underexplored Si(211) facet, toward its application in out-of-equilibrium Schottky diodes as autonomous power supplies. We also propose the electrochemical behavior of surface-confined redox couples as a diagnostic tool to anticipate whether or not a given surface will perform satisfactorily when used in a TENG design. [ABSTRACT FROM AUTHOR]

Gas‐sensitive materials are capable of dynamic identification and content monitoring of specific gases in the environment, and their applications in the field of gas sensing are promising. However, weak adsorption properties are the main challenge limiting the application of gas‐sensitive materials. A highly adsorbent gas‐sensitive cellulose nanofibril (CNF)‐based triboelectric material with a layered structure is prepared here and it is applied to self‐powered gas sensing. The layered structure of the triethoxy‐1H,1H,2H,2H‐tridecafluoro‐n‐octylsilane cellulose nanofiber (PFOTES‐CNF)‐based gas‐sensitive material further enhances the adsorption of the material due to electrostatic adsorption in the electrostatic field induced by triboelectricity. It is found that the ammonia‐sensitive material obtained by loading Ti3C2Tx in PFOTES‐CNF has a fast response/recovery (12/14 s), high sensitivity response (Vair/Vgas = 2.1), high selectivity response (37.6%), and low detection limit (10 ppm) for 100 ppm of ammonia gas. In addition, the ammonia‐sensitive CNF‐based triboelectric material can accurately identify NH3 concentration changes in the range of 10–120 ppm and transmit the signal wirelessly to the user interface, facilitating real‐time online monitoring of NH3 in the environment. A novel strategy is provided here for designing and preparing high‐performance gas‐sensitive composites and the analysis of self‐powered gas sensing is guided. [ABSTRACT FROM AUTHOR]

Designing materials with high triboelectric is an efficient way of improving output performance of triboelectric nanogenerators (TENGs). Herein, we synthesized a series of covalent organic frameworks (COFs) with similar skeletons but various functional groups ranging between electron‐donating and electron‐withdrawing. These COFs form an ideal platform for clarifying the contribution of each group to TENG performance because the pore wall is perturbed in a predesigned manner. Kelvin probe force microscopy and computational data suggest that surface potentials and electron affinities of COFs can be improved by introducing electron‐donating or withdrawing groups, with the highest values observed for fluorinated COF. The TENG with fluorinated COF delivered an output voltage and current of 420 V and 64 μA, respectively, which are comparable to other reported materials. This strategy can be used to efficiently screen suitable frameworks as TENG materials with excellent output performance. [ABSTRACT FROM AUTHOR]

Highly efficient and economical wearable piezoelectric energy harvesters are required to achieve future human‐integrated self‐powered electronics with stability. Herein, an all‐inorganic‐state fabric piezoelectric nanogenerator (FPNG) is developed for high‐performance energy harvesting using a spray‐coated lead‐free piezoceramic layer on a glass fabric. 0.5(Ba0.7Ca0.3)TiO3–0.5Ba(Zr0.2Ti0.8)O3 (BCTZ) sol–gel solution is deposited by spray coating, which is very facile and cost‐effective processing for the textile industry. It is well‐annealed and crystallized on the glass fabric endurable in high‐temperature processes. The BCTZ‐coated glass fabric is also treated by spraying silver nanowire (AgNW) solution onto both sides of the fabric to form robust electrodes. The all‐inorganic‐state FPNG can generate electrical output about the voltage of ≈3 V and the current of ≈110 nA which are high‐performance energy harvesting signals compared to previously reported fabric‐type energy harvesters. This high‐output energy harvesting results from the effective piezoelectricity of inorganic piezoceramics on the robust glass fabric. This work would open ways for future wearable self‐powered electronics integrated in general textile. [ABSTRACT FROM AUTHOR]

We report a fiber-structured hybrid nanogenerator wearable device fabricated on a single polyethylene terephthalate (PET) textile cylindrical substrate. The device can be described as a capacitor with inner and outer carbon-black-dispersed poly dimethyl siloxane (PDMS:Carbon black) electrodes, and zinc oxide and polyvinylidene fluoride (PVDF) as the dielectric medium between the electrodes. The compositional analysis in terms of X-ray diffraction, Fourier transform infrared spectroscopy, and scanning electron microscopy of the synthesized ZnO/PVDF has been measured and analyzed. The combined effect of triboelectricity between PDMS:Carbon black and PVDF, and piezoelectricity in a ZnO/PVDF hybrid, was investigated. Current–voltage characteristics were observed with varying load from 0–20 g, and resistance was observed to be decreased with load. Compared to earlier reports, there was a significant enhancement in voltage (≈5.1 V) and current (≈92.5 nA) at 10 g. Due to the introduction of interfacial polarization between PVDF and ZnO, the piezoelectric properties and pressure sensitivity of the hybrid ZnO/PVDF is enhanced. The hysterical behavior in the device's response while measuring voltage and current with varying time shows the signature of the triboelectric effect between PVDF and ZnO, as well as PDMS:Carbon black and ZnO/PVDF layers. Reduction of triboelectric behavior was confirmed with increasing relaxation time. Because of the enhancement in piezoelectricity, fiber-structured nanogenerator (FNG) ZnO/PVDF proved to a potential candidate to be used for wearable computing devices, such as smart watches and sports bracelets. [ABSTRACT FROM AUTHOR]

Triboelectric charge density and energy density are two crucial factors to assess the output capability of dielectric materials in a triboelectric nanogenerator (TENG). However, they are commonly limited by the breakdown effect, structural parameters, and environmental factors, failing to reflect the intrinsic triboelectric behavior of these materials. Moreover, a standardized strategy for quantifying their maximum values is needed. Here, by circumventing these limitations, we propose a standardized strategy employing a contact-separation TENG for assessing a dielectric material's maximum triboelectric charge and energy densities based on both theoretical analyses and experimental results. We find that a material's vacuum triboelectric charge density can be far higher than previously reported values, reaching a record-high of 1250 µC m−2 between polyvinyl chloride and copper. More importantly, the obtained values for a dielectric material through this method represent its intrinsic properties and correlates with its work function. This study provides a fundamental methodology for quantifying the triboelectric capability of dielectric materials and further highlights TENG's promising applications for energy harvesting. Determining the triboelectric charge and energy density of dielectric materials is generally limited by many factors, failing to reflect their intrinsic behaviour. Here, a standardized strategy is proposed employing contact-separation TENG and supressing air-breakdown to assess max triboelectric charge and energy densities leading to an updated triboelectric series. [ABSTRACT FROM AUTHOR]

Highlights: Development of new form of coupled nanogenerators to enhance performance. Energy in the form of light and vibration is successfully harvested, by converting an alternating current signal into a direct current signal. New approach to creating coupled nanogenerators, where multiple harvesting mechanisms by exploiting ferroelectric materials are achieved. Coupled nanogenerators have been a research hotspot due to their ability to harvest a variety of forms of energy such as light, mechanical and thermal energy and achieve a stable direct current output. Ferroelectric films are frequently investigated for photovoltaic applications due to their unique photovoltaic properties and bandgap-independent photovoltage, while the flexoelectric effect is an electromechanical property commonly found in solid dielectrics. Here, we effectively construct a new form of coupled nanogenerator based on a flexible BiFeO3 ferroelectric film that combines both flexoelectric and photovoltaic effects to successfully harvest both light and vibration energies. This device converts an alternating current into a direct current and achieves a 6.2% charge enhancement and a 19.3% energy enhancement to achieve a multi-dimensional "1 + 1 > 2" coupling enhancement in terms of current, charge and energy. This work proposes a new approach to the coupling of multiple energy harvesting mechanisms in ferroelectric nanogenerators and provides a new strategy to enhance the transduction efficiency of flexible functional devices. [ABSTRACT FROM AUTHOR]

The hands are used in all facets of daily life, from simple tasks such as grasping and holding to complex tasks such as communication and using technology. Finding a way to not only monitor hand movements and gestures but also to integrate that data with technology is thus a worthwhile task. Gesture recognition is particularly important for those who rely on sign language to communicate, but the limitations of current vision‐based and sensor‐based methods, including lack of portability, bulkiness, low sensitivity, highly expensive, and need for external power sources, among many others, make them impractical for daily use. To resolve these issues, smart gloves can be created using a triboelectric nanogenerator (TENG), a self‐powered technology that functions based on the triboelectric effect and electrostatic induction and is also cheap to manufacture, small in size, lightweight, and highly flexible in terms of materials and design. In this review, an overview of the existing self‐powered smart gloves will be provided based on TENGs, both for gesture recognition and human‐machine interface, concluding with a discussion on the future outlook of these devices. [ABSTRACT FROM AUTHOR]

The organic piezoelectric polymer polyvinylidene fluoride (PVDF) has attracted extensive research because of its excellent flexibility and mechanical energy-harvesting properties. Here, the electrospinning technique was taken to fabricate synthesized fiber membranes of a PVDF/cellulose acetate (CA) composite. The obtained PVDF/CA electrospun fiber membranes (EFMs) were employed to prepare a flexible nanogenerator. XRD and FTIR spectroscopy revealed the enhancement of piezoelectric behavior due to an increase in β-phase in PVDF/CA EFMs compared with cast films. The PVDF/CA fibers (mass ratio of PVDF to CA = 9:1) showed an output voltage of 7.5 V and a short-circuit current of 2.1 μA under mechanical stress of 2 N and frequency of 1 Hz, which were 2.5 and two times greater than those of the pure PVDF fibers, respectively. By charging a 4.7 µF capacitor for 15 min with the voltage generated by the PVDF/CA EFMs, nine LED lamps could be lit. The work provides an effective approach to enhancing the piezoelectric effects of PVDF for low-power electronic loading of macromolecule polymers. [ABSTRACT FROM AUTHOR]

In this article, triboelectric effect has been used to harvest mechanical energy from human motion and convert it into electrical energy. To do so, different ways of optimizing the energy generated have been studied through the correct selection of materials, the design of new spacers to improve the contact surface area, and charge injection by high-voltage corona charging to increase the charge density of dielectric materials. Finally, a triboelectric nanogenerator (TENG) has been manufactured, which is capable of collecting the mechanical energy of the force applied by hand tapping and using it to power miniaturized electronic sensors in a self-sufficient and sustainable way. This work shows the theoretical concept and simulations of the proposed TENG device, as well as the experimental work carried out. [ABSTRACT FROM AUTHOR]

Triboelectricnanogenerators (TENGs) is an efficient mechanical-electrical energy conversion method based on contact electrification and electrostatic induction coupling effect. The research on the application of TENGs is very necessary and valuable. Long jump is an influential and rapidly developing sport in sports. In this work, we designed a novel cotton cloth-based triboelectric nanogenerator (CC-TENG) to both harvest mechanical energy and monitor long jump. The cotton cloth and polydimethylsiloxane (PDMS) is used as the triboelectric layer. The prepared CC-TENG device has the advantages of portability, flexibility and foldability. The CC-TENG can achieve the maximum output power of 1.53 mW at a load of 9 MΩ. Moreover, the excellent reliability of CC-TENG can be observed. The CC-TENG was designed as the array CC-TENG to monitor long jump. This design will help to improve athletes' training results and promote the development of intelligent sports. [ABSTRACT FROM AUTHOR]

Multifunctional motion sensors have broad applications in the field of the internet of things (IoT). An octopus-shaped self-powered motion sensor is proposed to monitor the acceleration, motion direction, rotation speed and angle of objects. The charge transfer analysis of the sensor is carried out based on the positive piezoelectric effect, contact electrification effect and electrostatic induction. The influence of the surface microstructure and doping ZnO on the sensor sensitivity is investigated, and the improved film increases the sensor sensitivity by 13.58%. It is found that the output voltage decreases as the frequency increases. At the same frequency, the sensor output voltage amplitude is proportional to the acceleration amplitude. The test results show that the sensor can identify the motor rotation speed and angle, and the linear running direction and the motion state of the sweeping robot. Furthermore, the proposed sensor is cheap and beneficial for large-scale use. [ABSTRACT FROM AUTHOR]

Owing to the waste of energy originated by any physical or chemical process, approaches for reducing the energy losses have been conceived and, nowadays, energy recovery and conversion systems represent a worldwide‐recognized solution. The advent of colloidal‐based cybernetic systems highlights the essential role of energy harvesting, storage, and management capabilities coped by colloidal energetic systems. In this work, an alternative to thermoelectricity generation is demonstrated by means of a magnetic colloid based on Fe3O4 nanoparticles (NPs). The ferrofluid (FF) tribo‐ and pyroelectric features are explored in order to increase the amount of harvested energy. The findings suggest that the FF shows both triboelectric and pyroelectric charge displacement. A capacitive electrode is more efficient for accumulating potentials up to 48 V developed by triboelectricity while a resistive one is essential to collect pyroelectric charges up to 22 nA, which helped to estimate the FF pyroelectric coefficient, reaching the remarkable value of 25.2 μCm−2 K−1. A simplified equivalent model of the inductive setup is proposed, suggesting that increasing the fluid temperature a reduction of FF inductance due to demagnetization effects occurs. [ABSTRACT FROM AUTHOR]

Triboelectrification of polymers enables mechanical energy harvesting in triboelectric generators, droplet generators, and ferroelectrets. Herein, triboelectric polymers, inspired by the ordering in spider‐silk, with strongly enhanced contact electrification are presented. The ordering in polyether block amide (PEBA) is induced by the addition of inorganic goethite (α‐FeOOH) nanowires that form H‐bonds with the elastomeric matrix. The addition of as little as 0.1 vol% of α‐FeOOH into PEBA increases the surface charge by more than order of magnitude (from 0.069 to 0.93 nC cm–2). The H‐bonds between α‐FeOOH and PEBA promote the formation of inclusions with higher degree of macromolecular ordering, analogous to the structure of spider silk. The formation of these inclusions is proven via nanoindentation hardness measurements and correlated with H‐bond‐induced chemical changes by Fourier transform infrared spectroscopy and direct scanning calorimetry. Theoretical studies reveal that the irregularity in hardness provides stress accumulation on the polymer surface during contact‐separation. Subsequent molecular dynamic studies demonstrate that stress accumulation promotes the mass‐transfer mechanism of contact electrification. The proposed macromolecular structure design provides a new paradigm for developing materials for applications in mechanical energy harvesting. [ABSTRACT FROM AUTHOR]

Triboelectric nanogenerator (TENG) is a class of ambient mechanical energy harvesters used to augment the battery life of electronic devices such as sensors in implantables, wearables, and internet of things applications. In this work, the fundamentals of pre-biasing (precharging) the TENG at the start of the operation cycle to enhance the percycle extracted energy is presented. The energy gain is mathematically formulated, and the optimum pre-biasing voltage (equivalently charge) is derived by analyzing the energy exchange between the mechanical and the electrical domain over a periodic cycle. Further, a novel energy extraction circuit (EEC) termed as “pre-biased synchronous charge extraction (pSCE)” is introduced to 1) realize synchronous pre-biasing of TENG using the load battery itself and 2) achieve enhanced energy extraction from TENG. Energy output percycle is derived analytically for the pSCE circuit and compared to the state of the art synchronous charge extraction (SCE) circuit. The experimental implementation is performed for the proposed pSCE circuit that shows a 6.65 fold gain over the full wave rectifier (standard EEC) and 1.45 over the SCE circuit for a 5 V battery load. [ABSTRACT FROM AUTHOR]

A novel energy harvesting technique that uses conducted electromagnetic interference as an energy source is presented. Conducted EMI generated from fluorescent light using a switched‐mode power supply was measured and modeled as an equivalent voltage source. Two types of rectifier circuits—a bridge rectifier and a voltage doubler—were used as the harvesting devices for conducted EMI source. The matching networks were designed based on the equivalent model, and the harvested power was improved. The implemented energy harvester produces a regulated power over 68.9 mW and current over 15.1 mA while a regulated voltage can be selected between 3.3 V and 5 V. The proposed system shows the highest harvesting power indoor environment and can provide enough power for the Internet of Things devices. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Donghua University (Natural Science Edition) is the property of Journal of Donghua University (Natural Science) Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In daily life, some traditional interactive modes, such as keyboards and touch pads, still have a strong vitality and practical value.[[179], [571], [573]] Based on different physical transduction mechanisms, these keyboards or touch pads are essentially tactile sensors that transduce the physical touches into electrical signals and map them to corresponding positioning units.[[572], [574]] Converting physical movement into electrical signal is the original intention of TENG, which addresses the power/energy challenges of devices with powerful sensors nowadays.[555] Therefore, the self-powered TENG technology is exactly a good solution for developing a tactile sensor equipped on these devices.[[538], [540], [574], [576], [578]] In these applications, XY matrix scheme greatly reduces the number of channels and is conducive to high resolution wiring layout.[[575], [578]] In this scheme, crosstalk and target sensing resolution are the problems. This could improve the performance of HP-based piezoelectric device for mechanical energy harvesting, design of the photoferroelectric and photopiezoelectric devices, developing hybrid energy harvesters for multi-source energy harvesting, and developing eco-friendly, flexible, and high-performance devices. Early design of such an energy-aware interface (EAI) mainly consists of a voltage detector and a switch.[[506]] Once the voltage across the supercapacitor exceeds the threshold voltage of the voltage detector, the switch will be turned on to connect the wireless sensor system to the supercapacitor. [Extracted from the article]

As the Internet of Things becomes more and more mainstream, sensors are widely used in the field of motion monitoring. In this paper, we propose a lightweight and sensitive triboelectric nanogenerator (LS-TENG) consisting of transparent polytetrafluoroethylene (PTFE) and polyamide (PA) films as triboelectric layers, polydimethylsiloxane (PDMS) as support layer, and copper foil as electrode. LS-TENG can be attached to the joints of the human body, and the mechanical energy generated by human motion is converted into electric energy based on the triboelectric effect, thus realizing self-power supply. LS-TENG can monitor the angle changes in elbow and wrist joints when athletes pull the loop and actively generate the output voltage as a sensing signal, which is convenient for coaches to monitor the quality of athletes' hitting in real time. In addition, LS-TENG can also be used as a power supply for other wireless electronic devices, which facilitates the construction and transmission of large motion data and opens up a new development direction for the field of motion monitoring. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Textiles & Engineers / Tekstil ve Mühendis is the property of Union of Chambers of Turkish Engineers & Architects, Chamber of Textile Engineers and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The sustenance of the growing Internet of Things revolution requires suitable self‐powering solutions, which can be appropriately complemented by developing efficient energy harvesting systems. Typically, conventional piezoelectric thin film‐based energy harvesters are not promising due to high cost, low coverage area, and size‐frequency‐power trade‐off. Piezoelectric/triboelectric transduction driven mechanical energy harvesters (MEHs) based on nanocomposites offer better efficiency, cost‐effectiveness, and large‐scale production. Here, % weight ratio‐dependent piezoelectric/triboelectric property analysis, and optimization of Barium Titanate (BTO)/SU‐8 based photopatternable nanocomposite thin films are reported for developing highly efficient MEHs. Further, the performance of the nanocomposite is shown to be enhanced by controlled graphene nano‐platelet doping and ultraviolet (UV) exposure. Elaborate Finite Element Method (FEM) study is performed to support the experimental findings. Finally, three MEH devices are developed based on the optimally prepared variants of the nanocomposite and compared experimentally. A maximum output voltage of ≈3 V and power density of 0.65 µW cm−2 are obtained at 0.75 g and at the resonance frequency of 38 Hz from the graphene doped 20% BTO/SU‐8 based harvester. The prototypes have demonstrated the potential to deliver a regulated output voltage of 3.3 V within 40 s of periodic excitation upon integration with a customized power management unit for powering low‐power electronics. [ABSTRACT FROM AUTHOR]

Nanoenergy plays a vital role in the micro energy supply of sensors and wearable devices. Higher driving and sensing capabilities are very important for devices. A hybrid nanogenerator (HENG) with cascaded piezoelectric (PENG) and triboelectric nanogenerator (TENG) was designed. The BNBT/PVDF and BNN/PDMS composite films were used as the piezoelectric and triboelectric layers, respectively. The synergistic effect of the PENG and TENG units can improve the output signal. The open-circuit voltage of 120 V generated by the HENG is higher than that of the PENG and TENG. The obvious voltage signal is observed when the HENG is pressed by finger bending, palm tapping, and foot tapping. The stable output voltage of the HENG can drive 50 yellow LEDs. Therefore, the cascaded method provides a new design method for sensor and energy harvesting applications. [ABSTRACT FROM AUTHOR]

Free floating test masses (TM) of inertial reference instruments accumulate charge mainly through the triboelectric effect during separation from their housings and, if in the space environment, from cosmic radiation. These charges will degrade the accuracy of high sensitivity accelerometers and drag-free sensors. We demonstrate in ground testing two passive bipolar charge management systems using photoelectrons emitted from gold coated surfaces under illumination by ultraviolet light emitting diodes (UV-LEDs) with 255 nm, 275 nm, and 295 nm central wavelengths. The first method uses fast photoelectrons, generated by two 255 nm UV-LEDs with adjustable-intensity (through fine-tuning of their excitation currents) and illuminating the TM and its housing respectively. A second technique uses slow photoelectrons generated by one UV-LED, of either 275 nm or 295 nm, directed at the TM. Fast and slow electrons are defined as having kinetic energies after photoemission above and below e V T M max , where V T M max is the maximum allowable potential required for normal operation of the TM. In its optimized configurations and following an exposure of <30 s to UV, the fast-photoelectron control system converges to zero TM potential from ±1 V with a drift of ≈1.5 mV/day. The slow-photoelectron system requires about 5 min to converge to zero TM potential from 100 mV, with a similar drift of ≈2.0 mV/day. For reference, V T M max â‰... 80 m V for the LISA and LISA pathfinder sensors. Insight into the slow photoelectrons charge control method is provided by our simple Gaussian model of the work function for gold films (that approximates their quasi-triangular measured shape): 4.6 eV center, 0.2 eV standard deviation, and 4.30 eV and 4.90 eV cutoffs. The longest wavelength (lowest energy) photoemission is obtained with the 295 nm LED (11 nm FWHM) at about 285 nm (4.35 eV), where only about 3.5% of the photons have an energy above the photoelectric threshold. While the two-source UV fast photoelectron method is a modification of the LISA Pathfinder approach, the slow photoelectron method is a new passive charge management technique. These two passive techniques were developed for instruments without sensing and activation systems. For instruments with electric fields surrounding the TM and more complex geometries additional adaptations are required. [ABSTRACT FROM AUTHOR]