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A solid-liquid triboelectric nanogenerator (TENG) has attracted increasing research interest in relation to the development of regeneration energy based on water resources. The output of solid-liquid TENG remains unsolved, however, because of the low voltage output that impedes wide applications. To this end, in this work we developed a miniaturized microfluidic channel-based TENG device for highly efficient conversion of energy from the transport of a water droplet to an electrical output. We investigated an optimized design in a triboelectric material, the droplet transport and the electrostatic induction layer to provide a high voltage output and stable energy harvesting. The optimized device demonstrated maximum voltage amplitude 102 mV with an ultralow liquid consumption, 0.36 [Formula: see text], resulting in sample-energy conversion 283.33 mV/ [Formula: see text]. This novel device is expected potentially to address the limitations imposed by sample consumption in energy harvesting in the future.

Integrating smart functions into one flexible electronic is vastly valuable in improving their working performances and broadening applications. Here, this work reports a ultraflexible, highly efficient electromagnetic interference (EMI) shielding, and self-healable triboelectric nanogenerator (TENG) that is assembled by modified Ti3C2Tx MXene (m-MXene)-based nanocomposite elastomers. Benefitting from the excellent electronegativity of m-MXene, the single-electrode mode-based TENG can generate high open-circuit voltage (Voc) oscillating between − 65 and 245 V, high short-circuit current (Isc) of 29 µA, and an instantaneously maximum peak power density of 1150 mW m−2 that can power twenty light-emitting diodes (LEDs). Moreover, the resultant TENG possesses outstanding EMI shielding performance with the maximum shielding effectiveness of 48.1 dB in the X-band. The enhanced shielding capability is dominated by the electromagnetic absorption owning to high conduction loss in m-MXene network, multiple reflections between m-MXene sheets, and polarization effect on the surface of m-MXene sheets. Additionally, a self-powered wearable sensor is fabricated based on the as-prepared TENG. The sensor shows an intrinsic healing ability with healing efficiency of 98.2% and can accurately detect the human large-scale motions and delicate physical signal. This work provides an enhanced way to fabricate the wearable electronics integrated with smart functions, and the reported MXene-based TENG may have a broad prospect in the fields of aerospace, artificial intelligence, and healthcare systems.

Obtaining sustainable, high output power supply from triboelectric nanogenerators still remains a major issue which restricts their widespread use in self-powered electronic applications. In this work, an ultra-high performance, non-toxic, flexible Triboelectric nanogenerator based on Bismuth Tungstate (Bi2WO6): Polyvinylidene fluoride- trifluoroethylene (P(VDF-TrFE)) is fabricated. Hydrothermal technique is used to synthesize highly crystalline Bi2WO6 nanoparticles which were then incorporated inside the P(VDF-TrFE) matrix nanofiber mat using electrospinning over Aluminum coated PET substrate to yield a nanogenerator with device configuration of Cu coated PET/(Bi2WO6: P(PVDF-TrFE)) nanofiber mat/Al coated PET. Highly crystalline nature of biconcave shaped Bi2WO6 nanoparticles and β - P(VDF-TrFE) is confirmed by X-ray powder diffraction (XRD) and Raman spectroscopy techniques. The dielectric constant of Bi2WO6: P(PVDF-TrFE) nanofiber mat was studied and high dielectric constant of 44 was observed. The as-fabricated nanogenerator delivers a very high output voltage (open circuit) of 205 V and current density (short circuit) of 11.91 mA/m2 at ~ 0.15 kgf without any electric poling which is higher than all the prior reports in this field. Fabricated nanogenerator possesses very high output stability and ultra-sensitivity with swift response time of 545 ms. This outstanding performance of the nanogenerator can be ascribed to the synergistic combination of β-phase P(VDF-TrFE) polymer and non-centrosymmetric nature of Bi2WO6 nanoparticles. Further, a Bi2WO6 based pH sensor is driven by the energy obtained from the as-fabricated nanogenerator and the real time demonstration of nanogenerator powering a calculator is also demonstrated. The strategy outlined here presents a cost effective, high performance alternative for driving various portable bio- compatible self-powered electronic devices.

The rapid development of the Internet of Things has resulted in the harvesting of distributed sustainable energy receiving increasing attention. Recently, a study on triboelectric nanogenerators (TENGs) for collecting low-frequency and irregular-amplitude ocean wave energy has attracted significant interest. Herein, a self-powered seesaw-structured spherical triboelectric–electromagnetic hybrid nanogenerator (SSTE-HNG) combining various working modes is presented for harvesting wide-frequency wave energy from different directions and self-powered sea surface wireless positioning. The electrical output performances were systematically investigated and optimized via studying the effects of the configuration parameters, including the central slider mass, oscillation frequency, and swing amplitude of each module and the entire device; the instantaneous maximum output power densities of the origami zigzag-multilayer structured (OZ), freestanding layer rolling (FL), and electromagnetic generator (EMG) modules can reach 17, 4.8, and 9.8 W m−3, respectively, at an oscillation frequency of 0.7 Hz, and around 410 LEDs can be lit when operating the SSTE-HNG. Finally, the output voltage of the SSTE-HNG was stabilized using a transistor-controlled power management circuit for charging a 4.7 mF commercial capacitor in the range of 2.7 to 3.3 V; the seesaw-structured spherical buoy was used to drive a global positioning system (GPS) module for dynamic sea surface real-time wireless positioning, and our lab building on campus was successfully located upon installing the SSTE-HNG in a water tank. This study provides an ingenious design for achieving synchronized movements among hybrid effect/mode-based generators, and a self-powered buoy with a hybrid nanogenerator for sea surface wireless positioning was realized, which has the potential to be integrated with distributed electronics, such as sensors that collect sea surface meteorological information, in the future in the field of smart marine technology.

Neurological diseases associated with dysfunctions of neural circuits, including Alzheimer’s disease (AD), depression and epilepsy, have been increasingly prevalent. To tackle these issues, artificial stimulation or regulation of specific neural circuits and nuclei are employed to alleviate or cure certain neurological diseases. In particular, ultrasound neuromodulation has been an emerging interdisciplinary approach, which integrates medicine and engineering methodologies in the treatment. With the development of medicine and engineering, ultrasound neuromodulation has gradually been applied in the treatment of central nervous system diseases. In this review, we aimed to summarize the mechanism of ultrasound neuromodulation and the advances of focused ultrasound (FUS) in neuromodulation in recent years, with a special emphasis on its application in central nervous system disease treatment. FUS showed great feasibility in the treatment of epilepsy, tremor, AD, depression, and brain trauma. We also suggested future directions of ultrasound neuromodulation in clinical settings, with a focus on its fusion with genetic engineering or nanotechnology.

For achieving more effective mechanical energy conversion, based on low-cost and flexible polydimethylsiloxane (PDMS) and polyvinylidene fluoride (PVDF) polymer film as triboelectric and piezoelectric function layer respectively, a polymer-based hybrid piezoelectric-triboelectric nanogenerator (PT-NG) with a structure of Al/PVDF/Cu-PDMS/indium tin oxide (ITO)/polyethylene terephthalate (PET) has been demonstrated. The device has realized the simultaneous triboelectric and piezoelectric conversions in one structure. In addition, when PDMS and PVDF are further modified by graphene quantum dot (GQD) and titanium dioxide (TiO2) nanoparticles respectively, both triboelectric and piezoelectric outputs of the modified device are greatly enhanced synchronously. The experimental results have indicated that the increase of triboelectric output is due to the improvement of dielectric properties of PDMS film doped with conductive GQDs as well as the enhancement of the effective contact caused by the change of PDMS surface microstructure. While the promotion of piezoelectric output is mainly attributed to the fact that PVDF film after TiO2 modification induces more polarized β phase with a polarization-free process. Accordingly, the modified device converts mechanical energy into electricity more effectively, which shows a promising prospect in the fields of flexibility display, electronic skin, wearable electronic products and self-powered sensors.

Stray magnetic fields with a fixed frequency of 50/60 Hz are ubiquitous in buildings, factories, and power system equipment. Researchers are increasingly focusing on harvesting electrical energy from stray magnetic fields to provide sustainable energy for the Internet of Things (IoT) devices. Magneto‐mechano‐electric energy conversion is the most efficient way to convert low‐frequency stray magnetic fields into electricity. In this study, we proposed a hybrid piezo/triboelectric nanogenerator (HP/TENG) on the basis of a cantilever beam to use stray magnetic fields from the surrounding environment. The hybrid nanogenerator provided high output voltage/current and power of ∼176 V/375 μA and 4.7 mW (matched impedance of 20 kΩ) in a magnetic field environment of 4 Oe. The device provided a stable 3.6 V direct current output by incorporating energy management circuitry to sustainably drive power to commercial wireless temperature/humidity sensors. The HP/TENG has a significant application potential in IoT, which can use stray magnetic energy and a power wireless sensor system.

The high-voltage power source is one of the important research directions of triboelectric nanogenerator (TENG). In this paper, a high-voltage output TENG (HVO-TENG) is proposed with direct current/alternating current (DC/AC) optimal combination method for wind energy harvesting. Through the optimal design of a direct current generation unit (DCGU) and an alternating current generation unit (ACGU), the HVO-TENG can produce DC voltage of 21.5 kV and AC voltage of 200 V, simultaneously. The HVO-TENG can continuously illuminate more than 6,000 light emitting diodes (LEDs), which is enough to drive more possible applications of TENG. Besides, this paper explored application experiments on HVO-TENG. Demonstrative experiments indicate that the high-voltage DC output is used for producing ozone, while the AC output can light up ultraviolet (UV) LEDs. The HVO-TENG can increase the ozone concentration (C) in an airtight container to 3 parts per million (ppm) after 7 h and continuously light up UV LEDs. All these demonstrations verify that the HVO-TENG has important guiding significance for designing high performance TENG.

Smart sensors are expected to be sustainable, stretchable, biocomfortable, and tactile over time, either in terms of mechanical performance, reconfigurability, or energy supply. Here, a biocompatible piezoelectric electronic skin (PENG) is demonstrated on the base of PZT-SEBS (lead zirconate titanate and styrene ethylene butylene styrene) composite elastomer. The highly elastic (with an elasticity of about 950%) PENG can not only harvest mechanical energy from ambient environment, but also show low toxicity and excellent sensing performance toward multiple external stimuli. The synchronous and independent sensing performance toward motion capture, temperature, voice identification, and especially the dual-dimensional force perception promotes its wide application in physiological, sound restoration, and other intelligent systems.

Recycling of random mechanical energy in the environment has attracted great research interest in recent years. Herein, we report a rotating triboelectric nanogenerator (rTENG) based on GO@PVDF composite film. Benefit from the effective accumulation of electrostatic charges on the PVDF layers, the as-prepared rTENG shows high output performance. Its peak open-circuit voltage ( V o c ) and short-circuit current ( I s c ) are 35 V and 7.5 μ A, respectively, which are 3 and 3.5 times than pure PVDF based rTENG at 600 rpm, and the maximum power density calculated is 15.2 mW/m−2. Based on the as-prepared GO@PVDF-based rTENG, some practical applications are established, for example, lighting 12 led light bulbs to full brightness and sensing wind speed, which demonstrates the high feasibility and efficiency of the rTENG and manifests that the rTENG could be used in reusing random energy.

Sunflower seed is a popular food, but plenty of bio-waste sunflower husks are discharged into the world. If this bio-waste trash can be recycled, it will be reduced not only environmental pollution but also the waste of resources. In this paper, a triboelectric nanogenerator (SFP-TENG) based on a bio-waste sunflower husk powder is proposed and its open-circuit voltage, short circuit current, and instantaneous power are archived as 488 V, 28. 5 μ A , and 1200 μ W , respectively, under the frequency of 10 Hz with the excitation force of 58 N. The proposed SFP-TENG can harvest the biomechanical energy from the human body’s daily motions. The fabricated SFP-TENG device is capable of lighting up 153 commercial LEDs. Furthermore, the SFP-TENG device is also tested under various humid environments such as 38, 49, 60, 79, and 89% relative humidity. Additionally, it can power up microelectronic devices such as calculator and stopwatch. Hence, we are sure that the proposed device can promote cost-effective and eco-friendly green energy harvesting through recycling bio-wastes as sunflower husk.

Droplet motion state monitoring is important in microfluidic applications, such as biomedicine, drug delivery, and metal ion extraction. Here, a nonintrusion monitoring method of droplet motion state via liquid-solid contact electrification is proposed, and a triboelectric droplet motion state sensor (TDMSS) is fabricated. Droplet counting and droplet size monitoring can be realized by signal processing and information extracting of the voltage pulse. The experimental results show that the number of droplets increases linearly with the increase of liquid flow, and the linearity is 0.9854. Moreover, TDMSS can stably monitor the number of droplets in different motion states. In addition, the output pulse width is sensitive to droplet size, and the droplet length ranges from 3 to 13.5 mm. More importantly, TDMSS can realize the function of droplet counting and size monitoring of a conductive liquid and accurate droplet counting under different inclination angles and motion states. This work not only provides a nonintrusion method for droplet motion state monitoring but also makes a solid step for microfluidic sensing technology based on a triboelectric nanogenerator.

Vehicle passage sensors provide important information for the traffic monitoring system. Despite missing a large amount of passing vehicle data, inductive loop sensors are one of the most commonly ...

In recent years, triboelectric nanogenerators (TENGs) have developed rapidly and attracted the attention of researchers all over the world. Here, a novel waved-shaped triboelectric nanogenerator using the MgSiO3 powder (W-TENG) was developed. In this work, polyethylene terephthalate film and MgSiO3 powder form the triboelectric pairs. W-TENG devices can convert mechanical energy into electric energy. From the results, the maximum output power of a W-TENG can reach 184 µW. Additionally, a W-TENG can generate an open-circuit voltage (Voc) of 224.26 V, a short-circuit current (Isc) of 2.74 µA, and a transferred charge of 37.8 nC. Moreover, a W-TENG can serve as a self-powered human motion counter. This design describes a portable TENG device that can promote the self-powered human motion sensor application.

Highlights •Mechanical stimuli-triggered optical responses of cholesteric liquid crystal devices are realized.•Self-powered bistable smart window and E-paper are demonstrated.•Self-powered optical switch is developed for remote control.Intelligent responsive devices are crucial for a variety of applications ranging from smart electronics to robotics. Electro-responsive cholesteric liquid crystals (CLC) have been widely applied in display panels, smart windows, and so on. In this work, we realize the mechanical stimuli-triggered optical responses of the CLC by integrating it with a triboelectric nanogenerator (TENG), which converts the mechanical motion into alternating current electricity and then tunes the different optical responses of the CLC. When the voltage applied on the CLC is relatively low (15–40 V), the TENG drives the switching between the bistable planar state and focal conic state of the CLC, which shows potential applications in self-powered smart windows or E-paper displays. When the voltage supplied by the TENG is larger than 60 V, a self-powered optical switch is demonstrated by utilizing the transformation between focal conic state and instantons homeotropic state of the CLC. This triboelectric-optical responsive device consumes no extra electric power and suggests a great potential for future smart electronics.

This article presents a fully energy-autonomous temperature-to-time converter (TTC), entirely powered up by a triboelectric nanogenerator (TENG) for biomedical applications. Existing sensing systems either consume too much power to be sustained by energy harvesting or have poor accuracy. Also, the harvesting of low-frequency energy input has been challenging due to high reverse leakage of a rectifier. The proposed dynamic leakage suppression full-bridge rectifier (DLS-FBR) reduces the reverse leakage current by more than 1000 $\times $ , enabling harvesting from sparse and sporadic energy sources; this enables the TTC to function with a TENG as the sole power source operating at $\mu \text{m}$ 1P6M CMOS technology, consuming 0.14 pJ/conversion with 0.014-ms conversion time.

Electrostatic generators as a kind of effective energy harvesters have attracted intensive attention. However, the output of the generators is highly dependent on the charge density. Here, we demonstrate an all-in-one rotary electrostatic nanogenerator based on the charge pumping and voltage multiplying strategy (CV-ESG), which achieves high output power in SF6 atmosphere. CV-ESG integrates a pumping electret generator, a main generator, and a voltage multiplying and stabilization circuit on a pair of rotator and stator. We analyze the breakdown effect and its influence on the insulating layer covered on the electrodes through experiments. The breakdown voltage is high in SF6 atmosphere, and the maximum average power of CV-ESG in SF6 is 37.29 mW at 750 rpm, which is 3.29 times that in air. There is no surface friction in CV-ESG, which avoids abrasion and reduces friction damping. And the pumping generator is integrated with the main generator, making CV-ESG compact and easy to assemble. This work provides the design strategy for a high-power rotary electrostatic generator with good performance.

Lack of low-cost, large area deposition methods and photo-patternability of high-performance piezoelectric materials restrict the rapid development of efficient functional devices like sensors and energy harvesters. In this paper, we report an optimized process flow for Zinc Oxide (ZnO)/SU-8 and Barium Titanate (BTO)/SU-8 based nanocomposite thin films for mechanical energy harvesting (MEH) applications. Parametric variation of process variables for these nanocomposites reveals that 15% ZnO/SU-8 and 20% BTO/SU-8 nanocomposites show optimum results with good piezoelectric response and UV transmittance, allowing reliable lithography of the nanocomposites. Furthermore, three different types of energy harvesting devices are fabricated using these nanocomposites as piezoelectric layer. Output powers of $223~\mu \text{W}$ (ZnO/SU-8) and $642~\mu \text{W}$ (BTO/SU-8) are produced at resonance for the conventional cantilever type MEH devices at an input acceleration of 0.5g. Using the nanocomposites as flexible nanogenerator, open circuit voltages of 570 mV (ZnO/SU-8) and 780mV (BTO/SU-8) are obtained using regular finger pressing. The hybrid energy harvesters, based on combined piezoelectric-triboelectric transduction mechanisms, generate output voltages of 0.4V, 0.95V, 1.4V (ZnO/SU-8) and 0.7V, 1.1V and 1.9V (BTO/SU-8) in piezoelectric, triboelectric and hybrid operations, respectively.

Energy harvesting from natural resources has gained much attention due to the huge increase in the demand for portable electronic devices and the shortage of conventional energy resources in general. In the present work, the fabrication and realistic applications of a piezoelectric nanogenerator (PENG) using polydimethylsiloxane (PDMS) and the abundantly available, environment-friendly natural fiber Sonchus asper (SA) have been discussed. The biocompatible, low-cost SA fibers were flexible enough and showed high piezoelectric properties as active materials in the study. The SA pappus based piezoelectric nanogenerator demonstrated its ability to convert the harvested biomechanical energy into electrical energy from the various mechanical energy sources available in our environment. The SA pappus/PDMS thin film based piezoelectric nanogenerator (SPENG) fabricated in the laboratory showed colossal output performances (open circuit output voltage, V OC ∼81.2 V; short circuit current, I SC ∼1.0 μA) by continuous finger impartation. Uniform output performance was also obtained by the application of uniform force on the devices (e.g., ∼42 V for 5 N force at 10 Hz frequency). The SPENG was capable to charge a 2.2 μF capacitor to 3.2 V within a short time span (16 s) under continuous finger impartation and illuminate 39 commercial high-power blue LEDs that were connected in series. Thus, the fabricated SPENG can be used as a green and portable energy source to power up portable electronic devices. Apart from this, the SPENG may also be used as a self-powered energy supply for pacemakers or different types of health care units if properly improvised.

Knitted textiles as one kind of outstanding flexible substrate that have been universally applied in smart wearables. Structural design and output performance analysis of knitted-based triboelectric nanogenerators (TENGs) is significant research points. It is essential to provide inspiration in the TENGs applications. In this study, we designed and fabricated a fish-scale-based triboelectric nanogenerator using a formed knitted textile composed of commercial threads as a pair of contact areas. The deformation of the scale-shaped fabric was from the three-dimensional structure, which provided an effective contact area. We investigated the elastic yarn specification and scale-shaped distribution and analyzed their output performance in the frequency domain using fast Fourier transform. The result illustrated that the amplitude, phase, and power spectrum had obvious differences and can reflect the working states during the motions. The power spectrum could reach the maximum value of 280, which showed the potential for applications in the low-frequency motion.

Energy harvesting and power transmission is a significant challenge for the self-powered technologies towards mobile electronic devices. Here, we propose a hybridized energy harvester to complement each other’s strengths for simultaneously scavenging multiple types of energy and then wirelessly transmit the power. The harvester consists of electromagnetic-triboelectric nanogenerator units for collecting rotational energy and a commercial water-proof flexible solar cell. At a rotation rate of 500 rpm, the output current of electromagnetic-triboelectric nanogenerator units can reach about 630 mA through energy management. Moreover, the power harvested by hybridized energy harvester can be wirelessly transmitted up to a distance of about 100 cm in real time to charge mobile phone, anemometer, and hygrometer based on self-resonant coils. The hybridized energy harvester with wireless power transmission has potential applications in large-scale energy collection, long-distance wireless power transmission and sustainably driving mobile electronic devices.

With the rapid development of internet of things and wearable electronics, how to conveniently power uncountable sensors remains a huge challenge. Energy harvesting strategy is suggested to collect and convert environmental energies into electrical energy. Thereinto, piezoelectric polymers are utilized as flexible harvesters to convert mechanical energy. The latter widely distributes in both our daily life and industrial environment. Intrinsic piezoelectric property further drives piezoelectric polymers to construct flexible self-powered strain sensors. However, relatively low piezoelectric performance restricts their application in detection and conversion of weak mechanical excitations. Herein, wave-shaped 3D piezoelectric device was fabricated by embossing electrospun polyvinylidene fluoride nanofibers. This 3D structured device presents better longitudinal and transverse piezoelectric performance than usual flat-type one. This wave-shaped piezoelectric device was developed for acoustic detection and recognition with a frequency resolution better than 0.1 Hz. This wave-shaped device was capable of frequency spectrum analyses of various sound sources from human and animals and well presents its potential for future wearable acoustic sensors and transducers.

Mechanical energy is one of the freely available green energy sources that could be harvested to meet the small-scale energy demand. Piezoelectric nanogenerators can be used to harvest the biomechanical energy that is available in everyday human life and power various portable electronics. Herein, a ferroelectric material, i.e., lithium tantalate (LiTaO3), was synthesized and used to fabricate a flexible piezoelectric nanogenerator (FPNG). Generally, ferroelectric materials display a strong electrostatic dipole moment and high piezoelectric coefficient, thus resulting in enhanced electrical performance. First, LiTaO3 nanoparticles were synthesized and loaded into poly(vinylidene difluoride) (PVDF) to form a piezoelectric film and then, the piezoelectric composite film was sandwiched between two aluminum electrodes to fabricate an FPNG. The effect of the electrical performance of FPNG as a function of the concentration of LiTaO3 loaded into PVDF was systematically investigated and optimized. The 2.5 wt % FPNG exhibited open-circuit voltage, short-circuit current, and power density values of ∼18 V, ∼1.2 μA, and ∼25 mW/m2, respectively. Furthermore, the FPNG revealed good electrical stability and mechanical durability. Finally, the FPNG was employed as a weight sensor to harvest various biomechanical energies and operate low-power- electronics.

Triboelectric nanogenerator (TENG) is the new technique that can convert low-frequency mechanical energy into effective electricity. As an energy collector, the pursuit of high output characteristics is understandable. Although high charge density has been achieved by working in high vacuum or charge pumping techniques, it remains challenging to obtain the high output performance directly in the atmosphere. Herein, surface-engineering of the triboelectric layer for enhancing output performance has been reviewed carefully. By constructing surface morphology or developing surface modification, high performance of TENGs is finally presented in the review.

Coupling of energy harvesting unit with the energy storage one has already gained considerable attention in the development of self-powered portable gadgets. Nanogenerators (NGs) and flexible supercapacitors (SCs), both are considered as leading energy devices in their respective domains. Integration with each other opens up the new possibility of self-charging supercapacitors. Among, the NGs piezo-electric NGs are preferred over triboelectric NGs for integration with SC to avoid additional circuit complexity. Here, device architecture, the working principle, and imperative parameters regarding piezo-electric NG-based self-powered SCs are sequentially discussed. Finally, a conclusion is drawn from some recent works, and remarks are provided for cultivating its overall performance.

The marine internet of things (MIoT), an increasingly important foundation for ocean development and protection, consists of a variety of marine distributed sensors under water. These sensors of the MIoT have always been highly dependent on batteries. To realize in situ power supply, a flexible seaweed-like triboelectric nanogenerator (S-TENG) capable of harvesting wave energy is proposed in this study. The flexible structure, designed with inspiration from the seaweed structure, processes extensive marine application scenarios. The bending and recovering of the S-TENG structure under wave excitations are converted to electricity. As the output performance increases with the number of parallel connected S-TENG units, an S-TENG system with multiple units could serve for floating buoys, coastal power stations, and even submerged devices. Through the demonstration experiments performed in this study, the flexible, low-cost S-TENG could become an effective approach to achieve a battery independent MIoT.

A flexible and stable power supply is essential to the rapid development of wearable electronic devices. In this work, a transparent, flexible, temperature-stable and ionogel electrode-based self-healing triboelectric nanogenerator (IS-TENG) was developed. The ionogel with excellent stretchability (1,012%), high ionic conductivity (0.3 S·m−1) and high-temperature stability (temperature range of −77 to 250 °C) was used as the electrode of the IS-TENG. The IS-TENG exhibited excellent transparency (92.1%) and stability. The output performance did not decrease when placed in a 60 °C oven for 48 h. In addition, the IS-TENG behaved like a stable output in the range of −20 to 60 °C. More importantly, the IS-TENG could also achieve self-healing of electrical performance at temperatures between −20 and 60 °C and its output can be restored to its original state after healing. When the single-electrode IS-TENG with an area of 3 cm × 3 cm was conducted under the working frequency of 1.5 Hz, the output values for open-circuit voltage, short-circuit current, short-circuit transferred charge, and maximum peak power density were 189 V, 6.2 µA, 57 nC, and 2.17 W·m−2, respectively. The IS-TENG enables to harvest biomechanical energy, and drive electronic devices. Furthermore, the application of IS-TENGs as self-driven sensors for detecting human behavior was also demonstrated, showing good application prospects in the field of wearable power technology and self-driven sensing.

The high electronegativity between the atoms of two-dimensional (2D) group-III nitrides makes them attractive to demonstrating a strong out-of-plane piezo-electricity effect. Energy harvesting devices can be predicted by cultivating such salient piezoelectric features. This work explores the tribo-piezoelectric properties of 2D-indium nitride (InN) as a promising candidate in nanogenerator applications by means of first-principles calculations. In-plane interlayer sliding between two InN monolayers leads to a noticeable rise of vertical piezoelectricity. The vertical resistance between the InN bilayer renders tribological energy by the sliding effect. During the vertical sliding, a shear strength of 6.6–9.7 GPa is observed between the monolayers. The structure can be used as a tribo-piezoelectric transducer to extract force and stress from the generated out-of-plane tribo-piezoelectric energy. The A–A stacking of the bilayer InN elucidates the highest out-of-plane piezoelectricity. Any decrease in the interlayer distance between the monolayers improves the out-of-plane polarization and thus, increases the inductive voltage generation. Vertical compression of bilayer InN produces an inductive voltage in the range of 0.146–0.196 V. Utilizing such a phenomenon, an InN-based bilayer compression-sliding nanogenerator is proposed, which can tune the generated tribo-piezoelectric energy by compressing the interlayer distance between the InN monolayers. The considered model can render a maximum output power density of ~ 73 mWcm−2 upon vertical sliding.

A noise detection system (INDS) composed of an acoustic triboelectric nano-generator (TENG) and an electrical bilayer synaptic transistor (EDLT) is proposed. As a self-powered sound sensor, TENG converts the sound signal directly into a voltage signal output. EDLT is used as a neuromorphic device to simulate synaptic behavior in organisms and has the ability to store and process signals simultaneously. In this letter, a kind of intelligent, simple structure and humanized noise detection system is developed.

Wood is a state-of-art, renewable, and sustainable building material with excellent mechanical properties but negligible triboelectric polarizability. Strategies to improve and rationally tune the triboelectric properties of wood are needed to further its application for mechanical energy harvesting in smart buildings. We found that wood becomes more triboelectrically positive when modified by in situ-grown zeolitic imidazolate framework-8 (ZIF-8), a metal-organic framework (MOF), and more triboelectrically negative when coated with poly(dimethylsiloxane) (PDMS). A triboelectric nanogenerator (TENG) made with two radial-cut wood samples (L x R x T: 35 x 20 x 1 mm(3)), respectively functionalized with ZIF-8 and PDMS, can generate an open-circuit voltage (Voc) of 24.3 V and a short-circuit current (Isc) of 0.32 mu A upon 50 N, 80 times higher compared with that of native wood. We demonstrate the applicability of our functionalized wood TENG (FW-TENG) in smart buildings by using it to power household lamps, calculators, and electrochromic windows. ISSN:2590-2385

Converting various types of ambient mechanical energy into electricity, triboelectric nanogenerator (TENG) has attracted worldwide attention. Despite its ability to reach high open-circuit voltage up to thousands of volts, the power output of TENG is usually meager due to the high output impedance and low charge transfer. Here, leveraging the opposite-charge-enhancement effect and the transistor-like device design, we circumvent these limitations and develop a TENG that is capable of delivering instantaneous power density over 10 MW/m2 at a low frequency of ~ 1 Hz, far beyond that of the previous reports. With such high-power output, 180 W commercial lamps can be lighted by a TENG device. A vehicle bulb containing LEDs rated 30 W is also wirelessly powered and able to illuminate objects further than 0.9 meters away. Our results not only set a record of the high-power output of TENG but also pave the avenues for using TENG to power the broad practical electrical appliances., 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.

Along with the unceasing growth of worldwide economic and the associated issues on resources, energy and environment, clean energy generating technologies that are based on recyclable materials, if possible, may become the future trend of development. Here, we report the design of a cheap, lightweight, and recyclable single-electrode triboelectric nanogenerator (TENG) that utilizes waste paper as the triboelectric material. Under the current strategy, we successfully developed green energy machines without vastly increasing the mining of various critical minerals around the world. The as-designed TENG could not only collect and convert mechanical energy into electricity with sound efficiency, but also has the merit for continuous reuse and quick construction. The maximum output power density is as high as 171 mW·m−2 at a resistance of 130 MΩ and could be integrated into a book for monitoring reading actions, thus providing a new approach to the low-cost, green and sustainable self-powered electronic systems.

Recently, stretchable and wearable health monitoring equipment has greatly improved human’s daily life, which sets higher demands for portable power source in stretchability, sustainability, and biocompatibility. In this work, we proposed a stretchable triboelectric nanogenerator (TENG) based on stretchable poly (3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS)/porous carbon hybrid for oxyhemoglobin saturation (SpO2) monitoring. To combine advantages of carbon material for its high conductivity and organic electrode for its high stretchability, we spin-coated a solution of PEDOT:PSS/porous carbon onto a plasma-treated pre-stretched Ecoflex film to fabricate a stretchable electrode with rough surface. Due to its roughness and high potential difference with the dielectric material, the stretchable-electrode-based TENG exhibited better performance compared to the pristine TENG based on carbon or PEDOT:PSS material. The output voltage and current reached up to 51.5 V and 13.2 µA as the carbon concentration increased. More importantly, the performance further increased under large strain (100%) which is suitable for wearable systems. Finally, the device demonstrated its application potential for powering a flexible blood oxygen monitor. This simple and cost-effective method can enhance the stretchability and stability of organic/inorganic electrode-based TENG, which paves the development of high-performance stretchable TENG.

The serious environmental pollution and energy crisis have become a global issue, which makes it a pressing task to develop sustainable and clean energy sources. There exists a large amount of renewable energy in the ocean; unfortunately, most resources are underutilized. In this work, we demonstrate a performance-enhancing rolling triboelectric nanogenerator (TENG) based on nano-micro-structured polytetrafluoroethylene (PTFE) films. The nano-micro structure on the PTFE surface can increase the effective contact area and enhance the triboelectric effect, which is beneficial to improve the output performance. As a result, the output voltage and output current are 25.1 V and 7.3 μA, respectively. We further investigate the effect of nano-micro PTFE concentration on the output performance. The TENG based on a 45% concentration of nano-micro PTFE presents the maximum output power. Furthermore, this TENG can effectively harvest water wave energy with various amplitudes and frequencies, which has the potential to harvest ocean energy for environmental monitoring.

The triboelectric nanogenerator (TENG) is a promising technology for mechanical energy harvesting. TENG has proven to be an excellent option for power generation but typically TENGs output power drops significantly in humid environments. In this work, the effect of electrode’s material on power output, considering smooth and nanostructured porous structures with various surface hydrophobicity, is investigated under various humidity conditions. A vertical contact-separation mode TENG is experimentally and numerically studied for four surface morphologies of Ti foil, TiO2 thin film, TiO2 nanoparticulated film, and TiO2 nanotubular electrodes. The results show that the TENG electrical output in the flat structures such as Ti foil and TiO2 thin film at 50% RH is reduced to 50% of its initial state, while in the nanoporous structures such as nanoparticle and nanotube arrays, this is observed at RH above 95%. The results show that the use of porous nanostructures in TENG due to their high surface-to-volume, and that the process of water adsorption on the pore leads to better performance than the flat surface in humid environments. Based on our study, employing nanoporous layers is vital for nanogenerators either for power generation or active sensor applications at high humidity conditions.

This paper addresses a unimorph cantilevered piezoelectric nanogenerator having high ‎output power through vibrational energy harvesting that is simulated using finite element ‎method (FEM). The simulations are done for three types of perovskite piezoelectric ‎materials including PZT, PMN-PT and MAPbI3. The interdigitated electrodes were ‎exploited‏ ‏to obtain longitudinal vibration mode using d33 mode of piezoelectric layer during ‎the bending of nanogenerator structure. The presented structure consists of a piezoelectric ‎nanolayer with gold interdigitated electrodes on it, which is placed on a flexible PET ‎polymeric substrate. To encapsulate the piezoelectric layer, an SU-8 epoxy is placed over ‎the surface. The poling process is also simulated by applying high voltage through IDs to ‎piezoelectric layer. Generally, the electric potential distribution of the piezoelectric layer ‎must be performed by applying mechanical loadings. Then the output voltage, ‎power for free vibrations and base excitation (0.25-2g) of the nanogenerator at resonance ‎frequency are investigated. The resonance frequency of the PZT, PMN-PT, and MAPbI3 were ‎calculated to be 549 Hz, 560.5 Hz and 631 Hz, respectively. We found that PZT ‎piezoelectric materials yields maximum output voltage and electrical power values of 91.69 ‎V and 350 mW which shows better performance in vibrational energy harvesting ‎application. In comparison, the results of the simulation implied a good agreement with ‎other experimental studies. The unimorph piezoelectric energy harvester system generates ‎high voltage and output power in response to sub-kilohertz ambient vibration‎.‎‎

Non-contact triboelectric nanogenerator (TENG) enabled for both high conversion efficiency and durability is appropriate to harvest random micro energy owing to the advantage of low driving force. However, the low output (, High reliability is a huge challenge for sliding mode triboelectric nanogenerator (TENG). Here the authors develop a floating self-excited sliding TENG achieving both high durability and output for sustainable micro mechanical energy harvesting.

Sensors have recently gathered significant attention owing to the rapid growth of the Internet of Things (IoT) technology for the real-time monitoring of surroundings and human activities. Particularly, recently discovered nanogenerator-based self-powered sensors are potential candidates to overcome the existing problems of the conventional sensors, including regular monitoring, lifetime of a power unit, and portability. Halide perovskites (HPs), with an excellent photoactive nature, dielectric, piezoelectric, ferroelectric, and pyroelectric properties, have been potential candidates for obtaining flexible and self-powered sensors including light, pressure, and temperature. Additionally, the photo-stimulated dielectric, piezoelectric, and triboelectric properties of HPs make them efficient entrants for developing bimodal and multimode sensors to sense multi-physical signals individually or simultaneously. Therefore, we provide an update on the recent progress in self-powered sensors based on pyroelectric, piezoelectric, and triboelectric effects of HP materials. First, the detailed working mechanism of HP-based piezoelectric, triboelectric, and pyroelectric nanogenerators—operated as self-powered sensors—is presented. Additionally, the effect of light on piezoelectric and triboelectric effects of HPs, which is indispensable in multimode sensor application, is also systematically discussed. Furthermore, the recent advances in nanogenerator-based self-powered bimodal sensors comprising HPs as light-active materials are summarized. Finally, the perspectives and continuing challenges of HP-based self-powered sensors are presented with some opportunities for future development in self-powered multimode sensors.

Harvesting energy from ambient environment has been considered as a promising strategy for driving portable electronic devices in a sustainable way. A wind driven triboelectric-electromagnetic hybrid nanogenerator has been fabricated to convert wind energy into electricity. It is composed of an electromagnetic generator (EMG) and a triboelectric nanogenerator (TENG) with the output power of 35 and 0.32 mW, respectively when the wind speed is 5 m/s. Generally, TENG shows a low current output with a high voltage output characteristic, on the contrary the EMG shows a high current output and a low voltage output. This hybrid nanogenerator overcomes these problems and exhibits comprehensive and efficient performance on scavenging energy. Moreover, in view of the output performance and charging ability of the hybrid nanogenerator, it shows high stability, making it suitable for charging capacitors or batteries and driving portable electronics sustainably. A new structure of integrated TENG and EMG was designed to harvest wind energy, which shows potential applications in portable and small device power supply system, especially in the areas of remote mountains, deserts, islands, etc., as emergency power supply.

We report the development of low-cost triboelectric nanogenerators (TENGs) based on polypropylene (PP) fabrics formulated via an inexpensive melt-blowing process with an output voltage as high as 50 V. By disinfection methods such as exposure to steam, ethanol, and dry heat at 75 °C, the commercial medical masks and N95 filtering facepiece respirators (FFRs) can be reused to fabricate PP fiber based TENGs, which provide a novel regime for energy-harvesting devices based on reusable materials. As a power source, the output of one TENG can drive 15 serially connected light-emitting diodes (LEDs) or a commercial electric calculator. PP fabric TENGs can also work as self-powered sensors for the high-sensitivity detection of mechanical impact. We provide examples where the TENG is used to detect biomechanical motion such as that associated with the extension of an elbow, the touch of a finger, the impact of footsteps, and the bending of a knee without an external power supply. Most importantly, these PP fabrics for TENGs can be obtained from decontaminated medical masks that are generated as tremendous wastes every day, which provide a great potential as sustainable energy. These properties suggest that PP fabric based TENGs are promising for harvesting energy from biological systems and that they may facilitate the large-scale production of a new range of inexpensive self-powered multifunctional wearable sensors for applications in healthcare, security, and information networks.

Schottky-contacted sensors have been demonstrated to show high sensitivity and fast response time in various sensing systems. In order to improve their sensing performance, the Schottky barriers height (SBH) at the interface of semiconductor and metal electrode should be adjusted to appropriate range to avoid low output or low sensitivity, which was induced by excessively high or low SBH, respectively. In this work, a simple and effective SBH tuning method by triboelectric generator (TENG) is proposed, the SBH can be effectively lowered by voltage pulses generated by TENG and gradually recover over time after withdrawing the TENG. Through combining the TENG treatment with piezotronic effect, a synergistic effect on lowering SBH was achieved. The change of SBH is increased by 3.8 to 12.8 times, compared with dependent TENG treatment and piezotronic effect, respectively. Furthermore, the recovery time of the TENG-lowered SBH can be greatly shortened from 1.5 h to 40 s by piezotronic effect. This work demonstrated a flexible and feasible SBH tuning method, which can be used to effectively improve the sensitivity of Schottky-contact sensor and sensing system. Our study also shows great potential in broadening the application scenarios of Schottky-contacted electronic devices.

Self-powered implantable devices have the potential to extend device operation time inside the body and reduce the necessity for high-risk repeated surgery. Without the technological innovation of in vivo energy harvesters driven by biomechanical energy, energy harvesters are insufficient and inconvenient to power titanium-packaged implantable medical devices. Here, we report on a commercial coin battery-sized high-performance inertia-driven triboelectric nanogenerator (I-TENG) based on body motion and gravity. We demonstrate that the enclosed five-stacked I-TENG converts mechanical energy into electricity at 4.9 μW/cm3 (root-mean-square output). In a preclinical test, we show that the device successfully harvests energy using real-time output voltage data monitored via Bluetooth and demonstrate the ability to charge a lithium-ion battery. Furthermore, we successfully integrate a cardiac pacemaker with the I-TENG, and confirm the ventricle pacing and sensing operation mode of the self-rechargeable cardiac pacemaker system. This proof-of-concept device may lead to the development of new self-rechargeable implantable medical devices., Self-powered implantable devices have the potential to extend device operation, though current energy harvesters are both insufficient and inconvenient. Here the authors report on a commercial coin battery-sized high-performance inertia-driven triboelectric nanogenerator based on body motion and gravity that can be used to charge a lithium-ion battery and integrated into a cardiac pacemaker.

Establishing a sustainable energy supply is necessary for intelligent greenhouse environmental management. Compared with traditional energy, green and eco-friendly energy is more conducive to protecting the agricultural production environment. In this study, a fluorinated superhydrophobic greenhouse film is proposed as a negative triboelectric layer material for the construction of a triboelectric nanogenerator that harvests raindrop energy (RDE-TENG). Moreover, an upgraded configuration is adopted, where the bulk effect between the lower/upper electrode and film replaces the interfacial effect of the liquid-solid interface, thereby promoting charge transfer. The results show that the RDE-TENG can serve as a sustainable energy source for greenhouse temperature and humidity sensors that assists in realizing intelligent control of the environment and guides agricultural production processes. This device exhibits high-voltage and a stable output; thus, it has the potential to replace traditional energy sources, which helps toward realizing a self-powered intelligent greenhouse planting mode.

Ionogels with high transparency, stretchability and self-healing capability show great potential for wearable electronics. Here, a kind of highly transparent, stretchable and self-healable ionogels are designed using double physical cross-linking including hydrogen bonding and dipole–dipole interaction. Owing to the dynamic and reversible nature of the ion–dipole interaction and hydrogen bonds of polymeric chains, the ionogel possesses good self-healing capability. The multifunctional sensors for strain and temperature are fabricated based on ionogel. The ionogel can serve as strain sensor that exhibited high sensitivity [gauge factor (GF) = 3.06] and durability (1000 cycles) to a wide range of strains (0–300%). Meanwhile, the ionogel shows rapid response to temperature, due to the temperature dependence of its ionic conductivity. Furthermore, the ionogel fibers with excellent antifreezing (− 20 °C) capability are fabricated, and the fibers show the good sensing performance to human motions and temperature. Importantly, the antifreezing ionogel-based triboelectric nanogenerator (ITENG) is assembled for efficient energy harvesting. The ITENG shows a short circuit current (ISC) of 6.1 μA, open circuit voltage (VOC) of 115 V, and instantaneous peak power density of 334 mW m−2. This work provides a new strategy to design ionogels for the advancement of wearable electronics.

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

With advancements in the Internet of things (IoT) technology, the construction of the self-powered distributed sensor network is important. Here, we proposed a low-cost triboelectric nanogenerator based on soil (S-TENG) to convert mechanical energy into electrical energy, and meanwhile, it can serve as the self-powered pressure sensor. The natural soil and polytetrafluoroethylene (PTFE) film play the role of triboelectric layers. The electrical performance of the S-TENG (size: 5 cm × 5 cm) is 344.7 V, 34.8 µA, 68.95 nC, and 0.99 mW. Besides, we also design a self-powered pressure sensor based on the S-TENG, and the brightness of light-emitting diodes (LEDs) can reflect the pressure. This research can release a new applications for pressure monitoring.

Liquid-solid triboelectric nanogenerator (L-S TENG) is one of the major techniques to collect energy from tiny liquids, while the saturated charge density at the L-S interface is the key element to decide its performance. Here, we found that the saturated charge density of L-S contact electrification (CE) can be further increased under the illumination of an ultraviolet (UV) light. The fluorine-containing polymers and SiO2 are chosen as the electrification materials and with and without UV illumination on the L-S TENG. A series of experiments have been done to rule out the possible influences of anion generation, chemical change of solid surface, ionization of water, and so on. Therefore, we proposed that electrons belonging to water molecules can be excited to high energy states under UV illumination, which then transfer to solid surface and captured by the solid surface. Finally, a photoexcited electron transfer model is proposed to explain the enhancement of CE under the UV illumination. This work not only helps to further understand CE at L-S interface, but also offers an approach to further enhance the performance of L-S TENG, which can promote the TENG applications in the field of microfluidic systems, liquid energy harvesting, and droplet sensory.