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Three-dimensional tactile sensing in smart devices is witnessing an increasing demand. In this study, a three-dimensional tactile sensor is proposed according to the principle of triboelectricity by using polydimethylsiloxane (PDMS) and polyethylene oxide (PEO) films. Use of PDMS-ZnO composite films increases the output voltage of the electrodes. The sensor is designed with a cross beam-shaped pressure head to enable sensing normal forces in five directions. The working mechanism of the sensor is analyzed using the finite element method. The calculation results indicate a linear relationship between the output voltage and the force. The simulation results also demonstrate that the output voltage is linearly correlated with the applied force in the range of 1–30 N. Test results show that the sensor can sense the magnitude, frequency, and direction of the force as well as measure the duration of the force. The hardness of the object has a significant effect on the output voltage. Finally, the sensor is tested on a manipulator grasping an object to demonstrate its ability to sense the contact and sliding of the object.

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

Oceanic wave energy extraction through electrical generator is one of the most interesting topics in the field of power engineering. Almost all the existing relevant review paper focus on electrical generator with the working principle of electromagnetic induction or piezoelectric or triboelectric effect. In this paper, all the existing types (based on principle of operation) of electrical generator used for wave power harvesting are discussed. This paper not only covers recent progress in electrical power generation by electro-magnetic induction, piezoelectric generator, and electrostatic induction, but also presents critical comparative review as well where suitable use and weakness of each type of generators are discussed. Moreover, the application of advanced magnetic core, winding, and permanent magnets are discussed with extensive explanation which are not focused in the existing reviews. Various new constructional features of the electrical generators such as split translator flux switching, two-point absorber, triangular coil, dual port linear generator, piezoelectric, triboelectric nanogenerator, etc. are highlighted with principles of operation. It also includes emerging human intervened optimization method for determining optimum shape of generator and cooling system which is necessary to prevent demagnetization of the permanent magnet. Finally, the way of supply the generated electrical power form the generator to load/grid is thoroughly described in a separate section that would be obvious for successful operation. The comparison among all types of generators in terms of output voltage, current, scale of power production, power-frequency characteristics, power density, cascading, and approaches are tabulated in this paper.

The demand for using wireless sensors to monitor gases dissolved in transformer oil is growing and has brought challenges in the development of new sources of energy. Nano-generators are devices capable of converting mechanical energy, as vibrations, into electricity in a innovative and renewable way at low cost. In this work, the authors studied the addition of a steel spring to triboelectric nanogenerator (TENG) on the performance of its output power. Here, TENGs were built by using ZnO nanorods as donating electrons and PDMS:GO composites as negative material. PDMS:GO composites were prepared at different concentrations and the study was carried out in a wide frequency range (45 to 250 Hz). The addition of a steel spring to design of the TENG, as well as, 4% weight GO to PDMS improved the performance of the device. A power density around 246 mW m−2 , and output voltage of 4 V were obtained at 60 Hz. TENG’s ability to collect vibration energy from the wall of transformers and transform it into electrical energy is discussed based on the vibration frequencies obtained at different external points of transformers and performance of the devices.

A novel integrated multi-wall carbon nanotube /polydimethylsiloxane (MWCNTs/PDMS) and Polyvinylidene Fluoride (PVDF) based flexible triboelectric nanogenerator (TENG) was fabricated for energy harvesting application. The TNEG consists of minimal parts: aluminium (AI) electrode, PVDF layer and MWCNTs/PDMS layer. A surface roughness and thickness of −0.45 µm was measured for the fabricated MWCNT/PDMS respectively. The capability of the TENG in term of open circuit voltage (OCV) and short circuit current (SCC) was investigated by subjecting it to a force of 5 N, 10 N and 15 N at varying frequencies of 3 Hz, 5Hz and 7 Hz respectively. The maximum OCV of 21.6 V and SCC of 1.7 µA was obtained for an applied force of 15 N at frequency 7 Hz, respectively.

We present a comparative study on flexible capacitive sensors using three different mechanisms for vital sign monitoring. To record arterial pulse and respiration rate, sensors with a parallel-plate structure and engineered dielectrics with piezoelectric (BTO, PVDF - TrFE) fillers, polyurethane foam or triboelectric frictional layers are explored in this work. The sensitivity of the sensors with alternative mechanisms are compared by placing them on different locations on the body (wrist, neck and suprasternal notch). It is found that PU foam-based sensor is most sensitive option in terms of location and spectral content. Collectively, these sensors can be used in a multimodal patch developed for monitoring respiratory health as well as other abnormalities via sensor fusion.

Energy harvesters for smart wearables are gaining increasing attention world-wide. Among the various type of options availabel, triboelectric nanogenerators harvesting mechanical energy from human body movements are especially attractive. In this work, a flexible sandwich-type triboelectric nanogenerator (FS-TENG) based on ridged and biocompatible silicone elastomers and thermoplastic polyurethane is proposed. The proposed FS- TENG exhibits the open-circuit voltages and maximum power density of ~80 volts and 0.35 mW/cm2, respectively. This preliminary performance already makes the device extremely promising to power low energy smart wearable devices, as well as monitor pressure in bespoke biomedical applications.

In this world of rapid revolution, there is a constant flow of energy being generated and absorbed in our day to day life and industry. In order to generate energy different methods, as well as adaptation to environmental needs and sustainability issues, have all changed dramatically in the last decade. On the other hand, the energy use model has shifted dramatically as a result of increased mobility [6]. Long-term observation shows that with the rapid growth of the IOT and portable electronics, the need for a long-lasting and environmentally friendly portable power source is growing. Energy generation systems are an appealing choice for portable technology in this sense, but they still have a limited range of applications due to their low power output [3]. Triboelectrification is a natural and man-made phenomenon that can occur at any time and in any environment [9]. Despite the fact that triboelectrification occurs in all materials, a triboelectric sequence has been developed. Over the years it has been proven the feasibility of triboelectric effect and useful tribo-devices like triboelectric nanogenerators. And research have been done in this area to explore more. In order to gain a detailed understanding of energy harvests, triboelectric materials, triboelectric nanogenerators have been exploited in this work. This review examines the fundamental process of developing triboelectric energy harvesters [6].

The market for wearable sensors is growing rapidly as interest in personal health has recently increased, and the Internet of Things (IoT) has developed. However, supplying power to wearable sensors, such as body-attached flexible devices and E-skin, is still a matter of concern. Herein, we report a triboelectric nanogenerator (TENG)-based E-skin that can harvest bio-friendly energy and self-powered pressure sensing with its own power source. Au-coated Cu yarn and polytetrafluoroethylene-molded micro-patterned polydimethylsiloxane were used to fabricate E-skin with excellent stability, high sensitivity, elasticity, and flexibility. The TENG-based E-skin generates an output peak voltage and current of up to 200 V and 2.7 µA, respectively, and is stable with 4,500 cycles of pushing motion without any deterioration of the output signal. In addition, it is possible to operate an electronic watch by charging a capacitor and measuring the arterial pulse of the wrist as a pressure sensor. The results of this study present potential solutions for power source and signal monitoring within soft/wearable devices and human-machine interfaces.

As the demand for low-carbon and eco-friendly energy is increasing and the use of wearable devices is soaring, the triboelectric nanogenerator (TENG), which can economically harvest energy, is in the spotlight. Among many materials, paper is considered a promising substrate and frame material for self-powered TENG due to its high accessibility, flexibility, and biocompatibility. Here, we present a new structure of foldable paper based TENG (FP-TENG) composed of paper and PTFE/Si-rubber. The double-folded FP-TENG generates voltages and currents of 153 V and 2.2 µA, respectively, and shows excellent durability without signal degradation under 5,000 cycles of external force. A watch strap was manufactured with FP-TENG and integrated with an electronic watch pannel to supply power, and several LEDs were turned on. Therefore, FP-TENG is expected to be utilized as a promising eco-friendly energy source for small electronic devices.

New tactile sensing technologies have attracted more attention recently. Here, we demonstrated that the reduced graphene oxide/polyvinylidene fluoride (rGOPF) flexible film could effectively recognize, after triboelectrification, the 3-dimensional (3D) motions of human fingers with a polyethylene terephthalate (PET) cover through the induced positive/negative or strong/weak potential responses. Results show that this electrostatic induced potential could be up to $\sim 78\pm 8\ mV$ (touch mode) and $\sim 30\pm 5\ \text{mV}$ (touchless mode) under the defined conditions, respectively. A phenomenological scheme was proposed to explain these phenomena. It is based on the material microstructure and the classical theories of electrification and electrostatic induction, and confirmed via a series of experiments. To highlight the practical applications of this 3D-spatial sensing technique for human-finger electronics, two pairs of electrodes were integrated into an rGOPF flexible film to enhance its logic recognition capability from one axis to all directions. We illustrate its accurate recording capability for both Chinese character “” and English letters “K-S-A” as a touchless, self-powered flexible writing panel. This sensing technique provides a new sensing experience that the present array sensors via a touch mode cannot offer.

With the increasing in human population and decreasing in traditional energy methods made the human society all around to re-think towards Alternate energy sources. Moreover, potential usage of miniaturized electronic devices has been increasing in our day-to-day activities and their energy requirements also very less in terms of few mW/$\mu$ W. This paved a new path for many industrialist to turn their head towards energy harvesting techniques from human physiological body movements like walking, breathing, jogging, squatting etc., This research work mainly focuses on fabrication of Triboelectric nanogenerator using organic polymer materials PDMS Poly (dimethylsiloxane) which is a suitable candidate due to its interesting physical, electrical and mechanical property, cost effectiveness, user-friendliness, by low cost spin coating technique and subsequent annealing at $70-80^{\circ}C$.

Continuum robots have significant advantages in terms of high dexterity level and adaptability, leading to potential applications in narrow space operation and minimally invasive surgery. Endowing the tactile perception to the continuum robots will make them aware of collision. Here, we propose a self-powered triboelectric tactile perception ring (TTPR) that can sense tiny collision pressure in 4 directions. Integrating TTPR into each joint of the continuum robot enables the robot to aware collision and adjust posture. The demonstration of obstacle avoidance and adaptive crawling reveals that the proposed TTPR has the potential of being a promising solution for collision-aware of continuum robot.

A novel flexible triboelectric nanogenerator (TENG) was fabricated for energy harvesting applications. The TENG consists of graphite/polydimethylsiloxane (G/PDMS) composite on copper (Cu) as anode and polyvinylidene fluoride (PVDF) layer on aluminum (Al) as cathode. The G/PDMS composite was prepared by mixing G (6 wt%) and PDMS (74 wt%) in Toluene and bar coated on to a copper film. A surface thickness of 100 µm and 150 µm as well as a roughness of ~0.81 µm and ~1.5 µm was measured for the G/PDMS and PVDF, respectively. The capability of the TENG in term of open circuit voltage (OCV) and short circuit current (SCC) was investigated by subjecting it to a force of 4 N at varying frequencies of 3 Hz, 5 Hz and 7 Hz. Similarly, the OCV and SCC measurements were performed for 8 N and 12 N as well at different frequencies. A maximum OCV of 14 V and SCC of 3.2 μA was obtained for an applied force of 12 N at frequency 7 Hz, respectively.

Air breakdown effect, which restricts the increase of the surface charge density, is the major limitation for further improving the output performance of triboelectric nanogenerator (TENG). To solve this problem, a universal strategy which only requires adding an appropriate external capacitor to TENG is proposed in this work. By connecting a 68 pF external capacitor with a $2\times 2\ \text{cm}^{2}$ contact-separation (CS) mode TENG in parallel, the output energy per cycle can be increased to 2.5 times of that without an external capacitor. This research provides a novel and simple way to suppress the air breakdown effect and improve the output performance of CS-TENG.

This paper reports a highly-stretchable and Multi-Arched Asynchronous Triboelectric Sensor (MAATS) based on deformable ionic hydrogel for a novel method to measure motion displacement. Different from using the amplitude of output signal to predict displacement, it is the first time to figure out the length of displacement by a simple peak counting method. Three output channels can be achieved by setting three Arched Triboelectric units (ATUs) which share one flexible electrode of ionic hydrogel. Therefore, the output signals consist with the stretching state of the corresponding ATU. Therefore, the length of the displacement can be quantitatively estimated instantly due to the peak number of the three signal oscillograms, eliminating the output error caused by amplitude instability of triboelectric power generation. Excellent stretchability and stable output performances are also realized due to conductivity and deformability of the hydrogel. MAATS shows an instant response to reciprocating linear movements at 50% stretched state, 80% stretched state and 100% stretched state. This work provides a new application field of the hydrogel in sensors and a novel displacement measuring mechanism.

This work presents a triboelectric nanogenerators (TENG) based wide-range, self-powered flexible pressure sensor. The fabricated TENG can detect wide range of applied pressure from 3.2 to 1176 kPa. By analyzing the open-circuit voltage versus pressure curve, the sensitivity in three pressure regimes, namely low (1-10 kPa), medium-high (10-500 kPa) and ultra-high (>500 kPa) is extracted. The obtained sensitivities for these three pressure regimes are 3.16, 0.023 and 0.031 V•kPa-1, respectively. The origin of such a stable response of TENG at all of 3 pressure regimes lies in the use of real contact area of the interface pair. To the best of our knowledge, this is the first time a TENG as self-powered pressure sensor has been characterized over such a wide pressure range covering both low and super high pressures. These results show the potential of TENGs for a wide range of applications such as detecting the pressure in wearables, self-powered e-Skin for sole of humanoid robot to help them walk and stand, and the impact of wave energy.

Herein, we present a novel triboelectric nanogenerator based on nylon-11/poly-DADMAC and PVDF-TrFE nanofibers and demonstrate as a self-powered human motion sensor (SPHMS). The incorporation of cation poly-DAD MAC into the nylon-11 via the electrospinning method acts as a highly positive triboelectric layer that significantly enhanced dielectric constant by trapping surface charge in the composite materials. The fabricated SPHMS exhibited outstanding performance, including superior electrical performance (power 2.4 mW), excellent mechanical stability (>76k cycles), and sensitivity (1.01 V/KPa). As a proof of concept, the SPHMS was successfully demonstrated for monitoring human motion while walking, jogging, running, and jumping via a smartphone.

In recent years, wearable triboelectric nanogenerators (TENGs) have attracted attention due to its highly flexible, scalable, and low-cost features. Here in this paper, the authors have designed a sliding touch sensor which mimics the human skin to detect caressing touch based on the principle of triboelectric effect using COMSOL Multiphysics simulation software. Various triboelectric materials like Polytetrafluoroethylene(PTFE),Polyvinylchioride(PVC) and Polymethyl methacrylate(PMMA) were selected based on the triboelectric series for the comparative study on the effect of these materials on the proposed structure. The study of the device is carried out considering the voltage and charge variation obtained during the caressing of finger over the rectangular block of the polymer.

This paper reports a voltage regulation method with power management to enhance the reliability and stability of the self-powered flow rate sensor. Triboelectric energy harvesters are used both as the sensing signals and the power supply. One channel of the raw voltage from wind flow is regulated to a stable signal by the integral circuit, while the other channel is used for energy harvesting to provide the power for the whole circuit. Power management chip with ultra-low power consumption has been utilized with micro controller unit and antenna for wireless transmission. A low deviation of less than 2.5% has been achieved for the flow sensing signal and the temperature has also been monitored simultaneously, which shows promising application for the central air-conditioning system in smart buildings.

Bending, twisting or vibrations in coaxial and multi-wire cables can generate signal noise, often dominated by triboelectric charging effects. Cables that ensure low triboelectric noise are called low noise cables. These cables are used in many low-level measurement applications such as medical instruments and sensors in nuclear plant. In this work, we have designed a triboelectric charge meter that can detect and amplify charges at sub-femtocoulomb levels, sufficient to characterize the triboelectric noise in a wide range of high performance coaxial cables. During loop bending tests of, standard-, low noise-, and super-low noise coaxial cables, average microphonic noise levels of 2600 fC, 142 fC, and 2.9 fC respectively, were measured, i.e. super-low noise coaxial cables exhibits an almost 60 dB reduction of the triboelectric noise compared to standard coaxial cables and 35 dB compared to low noise cables.

Tactile sensing can provide sufficient cues concerning the geometry and texture of the contact in unknown environments. This paper proposes a semi-flexible triboelectric bionic whisker sensor (TBWS) as a novel scheme for robotic tactile perception. To be specific, it comprises power generation units (38mm in length, 18mm in width, and 10mm in thickness), octagonal plate, carbon fiber shaft (300mm in length, 1.5mm in diameter), shape memory alloy, and supporting parts. The octagonal plate hit the power generation units resulted from the carbon fiber shaft subjected to the external force, allowing to gene rate signals from the principle of via triboelectric and electrostatic induction. One another feature of the proposed sensors is that it is inspired by the structure of rat whisker follicles characterized by complex higher-order dynamics. Experimental result shows that TBWS can help robots accomplish autonomous work in complex environments. There is no doubt that the invention of sensor TBWS provides a new direction for robots’ future research.

The conversion of water energy into sustainable electricity has attracted more and more attention. Conventional water energy harvesting technologies are limited by manufacturing materials and output performance. The triboelectric nanogenerator (TENG) shows good performance in mechanical energy harvesting, while it has a relatively low short-circuit current and large inherent impedance. A novel high DC current output salt battery (SB) hybrid and enhanced by TENG (DC-SBHET) is proposed in this paper. The high open-circuit voltage generated by TENG can accelerate the velocity of mobile ions in the SB. The combination of TENG and SB can successfully increase the DC short- circuit current up to 18.1mA. Nano-foam electrodes were also chosen to further increase the battery performance.

Sound energy is a ubiquitous renewable energy source. How to comprehensively harvest and utilize this energy has become a hot research topic. Triboelectric Nanogenerator(TENG) can convert different forms of mechanical energy into kinetic energy, and has significant advantages in micro-nano power generation, self-driving sensing, and device performance control. This work designs an ultra-high power density Helmholtz resonant cavity based on triboelectric nanogenerator with a printed electrode(H-TENG) for harvesting acoustic energy efficiently. We proposed an optimized scheme for harvesting sound energy effectively by the special treatment of the electrode flexible film. Then we researched the structure of the resonant cavity, acoustic conditions, and the tension of flexible film, they can affect the output characteristics of the H-TENG acoustic energy converter. We find H-TENG follows the best output frequency deviation law, that is, introducing appropriate tension according to a specific sound wave range can improve the best frequency response. Compared with the best results in the early literature, the H-TENG has a high power density of 1.47 W/m2 sound pressure. The study showed that the high power output of H-TENG can light up 457 LEDs at the same time. Finally, this research also proposes the application potential of H-TENG in energy conversion and acoustic sensing.

Several species of terrestrial and marine organisms like seals, use their vibrissae (whiskers) as important tactile sensors to find and follow underwater wakes. Here, we propose a bionic-tactile sensor (BTS) based on triboelectric nanogenerator to capture complex stimuli by organisms moving through water, and utilize received signal to track the hydrodynamic trails. One of the BTS's essential features is that triboelectric nanogenerator coupled with inspired by the structure characteristics of seal whiskers, which leads to the highly-sensitive detection of stimuli. Another is that our design is self-powered without additional power supply. Experiments show that the designed BTS has the ability to perceive the hydrodynamic trails left by underwater moving objects. Moreover, the relationship between the output signal and the movement parameters is linear, and we use this principle to perceive the relative motion state of the moving object. These new insights into the biological basis of tactile perception using whiskers provides new design guidelines to develop efficient underwater robotic sensors.

In this paper, a novel hybrid-sensor integrating TENG and inductive sensor is proposed to acquire the triboelectric and inductive signals from different objects. A matching CNN algorithm was used to process the above signals in order to achieving highly accurate recognition. The identification accuracy of different solid surfaces reached 98.89% and the identification accuracy of different solution reached 95%. As a demonstration, we designed a real-time identification system for effective sorting of different items.

This paper present the conical Helmholtz resonator-based triboelectric nanogenerator (CH-TENG) designed for highly efficient harvesting of acoustic energy in various occasions. This CH-TENG consists of an acoustic collecting tube, a conical Helmholtz resonant cavity and an aluminum film with uniform distributed pinholes, and a dielectric soft film with one side ink-printed for electrode. Furthermore, the effects of resonant cavity structure, sound wave frequency, sound pressure level and sound collection tube on the performance of CH-TENG are systematically studied. Compared with previous research, the proposed CH-TENG can generates higher acoustic sensitivity per unit area and power density per unit sound pressure, because the acoustic collecting tube structure gathers more sound waves and sound wave amplification capability of the Conical Helmholtz Resonator stronger. Meanwhile, this new technique to some extent can serve as a sensor.

This paper proposed a hybridized energy harvester combining electromagnetic, piezoelectric, and triboelectric transduction mechanisms for ocean wave energy harvesting. Two energy harvesting mechanisms of wave shaking and heaving are contained in this device. The shaking energy harvesting mechanism (S-EHM) consists of a compound pendulum mechanism and a gear mechanism. Together with an electromagnetic generator (EMG) and a piezoelectric generator (PEG) are used to harvest the shaking energy of ocean waves. The heaving energy harvesting mechanism (H-EHM) consists of a sliding sub, mass slider and springs. Meanwhile, the triboelectric nanogenerator (TENG) is used to harvest the undulations energy of ocean waves. They all supply energy to the electrical appliances inside the marine buoy, which can extend its working life. The diameter of the harvester is 140 mm and the height is 185 mm. The tested maximum output voltages of the electromagnetic, piezoelectric and triboelectric parts are 12V, 18V, and 55 V, respectively. Moreover, the device can light up at least 90 LEDs and can power the temperature and humidity sensor to display the ambient temperature.

Traditional vibration sensor of ship machinery using cable for power supply cannot meet the requirements of a large number of distributed sensors of the intelligent ship. A bouncing-ball based triboelectric nanogenerator (BB-TENG) to be used as a self-powered vibration frequency monitoring sensor is proposed. In the sensing test, the vibration frequency of 15 ∼ 50 Hz under different amplitudes can be measured accurately. The frequency calculation of the voltage signal can accurately reflect external vibration frequency, while the change of short-circuit current has linear relationship with the frequency, and the correlation coefficient is about 0.99. In addition, electrical signal test results and photos taken by high-speed cameras show that the limit of the available detection frequency of BB-TENG increases with the increase of amplitude and support height. The electrical output of BB-TENG under different working conditions are tested, which provides the basis for selecting suitable BB-TENG according to different vibration characteristics.

Powering marine distributed nodes (e.g. monitoring buoys) has always been challenging under the harsh conditions in oceans. Triboelectric nanogenerator (TENG), on account of its robustness and cost, provide a novel solution to this problem. In this study, a stackable TENG (S-TENG) consisting of polytetrafluoroethylene pellets, an acrylic plates coated with aluminum film and a 3D-printed brace, has been proposed to harvest wave energy efficiently. Experiments show that each S-TENG unit produces a maximum peak power of 25.22mW while a power density of 34.65W/m3 is achieved. The output characteristic of multiple S-TENG units parallel connected is studied. It turns out that the output performance yields linear increase with the unit number without having to use rectifier bridge. This feature indicates that self-powered marine monitoring buoy is achievable by S-TENG integration.

Wearable electronics and electric skin attract increasing attention, which demand high transparency, extensibility, and biocompatibility. In this work, a transparent and highly stretchable pyramidal hydrogel-based triboelectric nanogenerator (HTG) for tactile sensation and neck movement detection is reported. Hydrogel can be easily stretched to 800% of the initial length. The output property of HTG could reach up to 360V and 1.27mW. Meanwhile, a slight signal like blowing could also be detected by the proposed device. Besides, the charging time of the capacitor reveals the dependence of output property and frequency. This work provides a brilliant method for self-powered physiological signal monitoring.

There are many studies on the use of solid-liquid triboelectric nanogenerator (TENG) to harvest energy from water motion to obtain sustainable electrical energy, but there are very few studies on the collection of oil Kinetic energy. Insulating oil is a kind of liquid dielectric with good physical and chemical properties, dielectric properties, and flow characteristics. It is widely used in power equipment and plays the role of electrical insulation, convection heat dissipation, and arc suppression. We have invented a TENG that can be used to harvest the energy of oil motion. Different structural designs have verified that TENG can effectively collect the mechanical energy generated by oil motion. The generator producing an open circuit voltage of up to 100V, and a short circuit current of up to 0.5µA. Also, using reactive ion etching (RIE) technology to process the surface of the solid insulating material with microstructures, the output of TENG is increased by about five times. The research content of this paper provides experimental support for detecting the electrification degree of the oil flow in the transformer through TENG. The designed TENG can be further applied to the oil flow electrification detection of power equipment.

This paper discusses the parametric study of a sponge-based triboelectric energy harvester (SBTENG). Different from the conventional energy harvester, we introduce microporous in our prototype to create a sponge-like structure. The porous is hypothesized to trap the charge from the kinetic movement and, hence, increase - the voltage output. To prove the hypothesis, numerical simulation has been conducted and it shows that the introduction of the porous structure can improve the charge difference by 50.8%, as compared with the nonporous structure. To characterize, we have further performed experimental studies to investigate the electrical output at 0%, 25%, 45%, and 65% NaCl concentration. The result shows significant improvement of the electrical output in the NaCl concentration. We also demonstrated a proof-of-concept experiment to power up LEDs using our developed SBTENG. This study provides a useful guideline for the triboelectric sensor design.

This paper reports a novel high-deformable and transparent triboelectric hydrogel sensor (THS) with anti-freezing and anti-drying properties for physiology sensing and motion monitoring. It is the first time to fabricate the micro-pyramidal structure on hydrogel's surface for a highly sensitive self-powered sensor. Excellent mechanical and electrical performances can be obtained due to deformable and conductive ionic hydrogel with anti-freezing and anti-drying properties. It shows no significant variations of output signals after being stored at −20°С for seven days and 60°С for 1-day compared with placed at room temperature. Besides, combined with the same processing method of the triboelectric PDMS layer, THS shows an instant response to physiological movement, including breathing with a mask, finger bending and sitting/squatting down. This work provides an insightful method for hydrogel in the application of the physiological sensors field.

The surface charge density of the tribo-layer is the paramount parameter to determine the electrical output of triboelectric nanogenerator(TENG). Most previous works focused on high dielectric metal particle doping. However, metal nanoparticles will form charge leakage channels in the triboelectric layer, which will reduce the surface charge density and thus weaken the output of TENG. In this paper, a new doping scheme of SiO 2 @Ag composite particles was proposed. By attaching Ag nanoparticles to the surface of SiO 2 microspheres, the problem of Ag nanoparticles being easily agglomerated due to the surface potential energy was not only solved, but the SiO 2 microspheres could construct a blocking layer in the triboelectric layer to prevent the leakage of surface charges. The output performance of reported TENG significantly yielded 241 µC/m2 in charge density, giving over 3.45-fold enhancement to the unadulterated TENG. As such, the demonstrated TENG could potentially serve as sensitive electromechanical energy conversion device, and provides a promising power solution for MEMS transducers and energy harvesting applications.

Electronic skin (e-skin) is a kind of artificial skin, which has great application value in the fields of sensors, signal monitoring and human-machine interaction. This paper proposes a new type of self-powered flexible hybrid wearable e-skin system based on the combined working mechanism of Single-Electrode mode Triboelectric Nanogenerator (SE-TENG) and Piezoelectric Nanogenerator (PENG). The electrode and piezoelectric material are designed into a serpentine grid structure, which greatly improves the stretchability. The open circuit voltage (V OC ) is ~100V, the short circuit current (I SC ) is ~10µA, and the power density is as high as 1mW / cm2. The system can not only be used as a self-powered sensor to detect physical signals in real time, but also can achieve high-precision positioning functions, which has extremely broad application prospects in the field of artificial intelligence.

Herein, a self-powered motion sensor (SPMS) based on PVDF-TrFE/MXene nanocomposite is newly presented for real-time human motion monitoring. The incorporation of MXene nanosheet into the PVDF-TrFE matrix via the electrospinning process act as a highly negative triboelectric layer with high surface charge density and dielectric constant. The fabricated SPMS exhibited superior performance at low pressure including high electrical output performance (power 4.02 W/m2), excellent mechanical response sensitivity (1.1 V/kPa), and stability (>20000 cycles). Based on its performance, the SPMS was successfully demonstrated to control automatically electrical home appliances and real-time human motion monitoring during the process of walking and running.

This paper reports a high-efficiency raindrops energy harvester using the interdigital electrode. With the new electrode deployment and connection scheme, the proposed raindrops energy harvester shows excellent energy conversion effeciency up to 2.5%, over 250 times higher than the conventional interdigital electrode-based triboelectric nanogenerator with efficiency of only 0.01%. The performance under the different finger electrodes was investigated. Note that the first electrode of the interdigital electrode is designed for the energy harvesting and the rest are utilized to detect the raindrops speed. We also find out that the open-circuit voltage varies with the tilt angle of the structure, of which the inclination angle of 45 degrees shows the best output performance. And under the condition of 0 degree, the open-circuit voltage first decreases and then gradually remains stable, rather than showing no voltage output. The proposed raindrops generator pushes forward a significant step of realizing raindrops energy harvesting in real-world application.

In the Internet of things, a large number of sensors are needed, triboelectric nanogenerators(TENG)has been proved to be the best solution for energy supply. However, the traditional friction nano-generator has large voltage, small current, large internal resistance and small output power. Therefore, we report a gel-based Solid Ion Channel Battery (SICB) that can greatly improve the output performance compared to traditional triboelectric nanogenerators. Based on the traditional TENG, using PTFE(Polytetrafluoroethylene) and Cu as the friction layer, the ion gel was affixed to the back of copper, and different sodium chloride concentrations were experimentally tested. Finally, it was found that the SICB can achieve 260V open circuit voltage and 0.09mA short circuit current.

A smart soft robotic manipulator using a triboelectric tactile (TT) sensor for contact detecting and a triboelectric bending (TB) sensor for deformation monitoring is developed with (Internet of things) IoT module to collect the data and machine learning (ML) algorithm to fuse the output of two types of sensors, realizing grasped objects recognition with high accuracy of 97.321% for 28 different shapes of objects. The time-related features hidden in the triboelectric spectrum, i.e. contact sequence, collision vibration, etc., other than the individual physical information calculated from the output signal, greatly enhance the recognition ability of the integrated intelligent system. By leveraging the IoT and artificial intelligence (AI) analytics, an augmented reality (AR) enabled product preview system is successfully implemented based on the AIoT platform, showing the potential of the integrated system in unmanned shop applications.

Origami, an ancient art of paper folding with a history spanning over 1000 years, can devise ingenious patterns with unique advantages in terms of great flexibility, lightweight, extreme simplicity, and excellent shape adaptability. The poor stability of electret / triboelectric devices in a humid environment is a key challenge faced by researchers worldwide. Inspired from Japanese Muira-origami structures, we propose a "W-tube" shaped triboelectric nanogenerator (WTN) with the two pieces of electret films encapsulated inside to isolate the humid environment. Besides, it's capable of capturing energy from various moving scenes, including horizontal or vertical pressing, and lateral bending. We have tested multiple parameters of WTN in detail, including the influence of the number of generating units, the original height of equipment, the acceleration and the excitation direction on the output performance. This work combines the ancient origami art with energy conversion technology to create a multifunctional waterproof energy harvesting device.

Since its first discovery in 2014, laser-induced graphene (LIG) has gained increasingly attention as a simple and low-cost alternative to printing techniques, which instead require additional materials such as functional ink or adhesive layers. While there are several works on LIG supercapacitors, gas sensors, and triboelectric generators, this method is still very unexplored for antennas, especially if realized on eco-friendly paper substrates. In this paper, we realized a microstrip patch antenna using LIG on a food-derived cellulose-based paper. The antenna was first designed and simulated using a High-Frequency Structure Simulator (HFSS) software, using different values of relative permittivity ϵ r (from 2 to 3.6), to understand the impact of laser-induced graphitization of the substrate on the resonance frequency. The subsequently fabricated antenna showed a strong resonance peak of −25dB at 2.4 GHz, corresponding to an ϵ r of 2.2, in agreement with experimental results.

As for any electrostatic transducer, triboelectric energy generators (TENGs) need to maximize their bias voltage for a good kinetic-to-electrical energy conversion. If several hundreds of volts can be obtained directly by triboelectric contacts for some state-of-art devices, unstable charge-pump (UCP) conditioning circuits can also be used to reach such high values with more basic TENGs. Whatever the chosen solution, this high-voltage must be reduced to a few volts to power an electronic device. In this abstract, we first compare the three main UCPs and we propose to use an autonomous MEMS micro-plasma switch in a Buck DC-DC converter in order to maximized the voltage across the TENG while obtaining a low voltage rectified output without any external control.

This paper deals with a review of potential technical applications of piezoelectric polymer systems for Industry 4.0 applications. Polyvinylidene difluoride (PVDF) is a highly non-reactive thermoplastic fluoropolymer produced by the polymerization of vinylidene difluoride. Copolymers of PVDF with beta phase could be used in piezoelectric and triboelectric applications which are presented in this paper. PVDF is a candidate for harvesters and sensors that cannot be realized with piezoceramics or single crystals. Both technical applications for sensing and energy harvesting are presented in this paper. These technologies could be useful in mechanical engineering applications like a strain sensor, strain energy harvesting, vibration energy harvester, load sensing and triboelectric sensors/generators. The opportunity for future usage in Industry 4.0 devices is outlined and experimental results of individual systems are presented.