We report human skin based triboelectric nanogenerators (TENG) that can either harvest biomechanical energy or be utilized as a self-powered tactile sensor system for touch pad technology. We constructed a TENG utilizing the contact/separation between an area of human skin and a polydimethylsiloxane (PDMS) film with a surface of micropyramid structures, which was attached to an ITO electrode that was grounded across a loading resistor. The fabricated TENG delivers an open-circuit voltage up to −1000 V, a short-circuit current density of 8 mA/m2, and a power density of 500 mW/m2 on a load of 100 MΩ, which can be used to directly drive tens of green light-emitting diodes. The working mechanism of the TENG is based on the charge transfer between the ITO electrode and ground via modulating the separation distance between the tribo-charged skin patch and PDMS film. Furthermore, the TENG has been used in designing an independently addressed matrix for tracking the location and pressure of human touch. The fabricated matrix has demonstrated its self-powered and high-resolution tactile sensing capabilities by recording the output voltage signals as a mapping figure, where the detection sensitivity of the pressure is about 0.29 ± 0.02 V/kPa and each pixel can have a size of 3 mm × 3 mm. The TENGs may have potential applications in human–machine interfacing, micro/nano-electromechanical systems, and touch pad technology.

We report a single-electrode-based sliding-mode triboelectric nanogenerator (TENG) that not only can harvest mechanical energy but also is a self-powered displacement vector sensor system for touching pad technology. By utilizing the relative sliding between an electrodeless polytetrafluoroethylene (PTFE) patch with surface-etched nanoparticles and an Al electrode that is grounded, the fabricated TENG can produce an open-circuit voltage up to 1100 V, a short-circuit current density of 6 mA/m(2), and a maximum power density of 350 mW/m(2) on a load of 100 MΩ, which can be used to instantaneously drive 100 green-light-emitting diodes (LEDs). The working mechanism of the TENG is based on the charge transfer between the Al electrode and the ground by modulating the relative sliding distance between the tribo-charged PTFE patch and the Al plate. Grating of linear rows on the Al electrode enables the detection of the sliding speed of the PTFE patch along one direction. Moreover, we demonstrated that 16 Al electrode channels arranged along four directions were used to monitor the displacement (the direction and the location) of the PTFE patch at the center, where the output voltage signals in the 16 channels were recorded in real-time to form a mapping figure. The advantage of this design is that it only requires the bottom Al electrode to be grounded and the top PTFE patch needs no electrical contact, which is beneficial for energy harvesting in automobile rotation mode and touch pad applications.

We report a triboelectric nanogenerator (TENG) that plays dual roles as a sustainable power source by harvesting wind energy and as a self-powered wind vector sensor system for wind speed and direction detection. By utilizing the wind-induced resonance vibration of a fluorinated ethylene-propylene film between two aluminum foils, the integrated TENGs with dimensions of 2.5 cm × 2.5 cm × 22 cm deliver an output voltage up to 100 V, an output current of 1.6 μA, and a corresponding output power of 0.16 mW under an external load of 100 MΩ, which can be used to directly light up tens of commercial light-emitting diodes. Furthermore, a self-powered wind vector sensor system has been developed based on the rationally designed TENGs, which is capable of detecting the wind direction and speed with a sensitivity of 0.09 μA/(m/s). This work greatly expands the applicability of TENGs as power sources for self-sustained electronics and also self-powered sensor systems for ambient wind detection.

A spherical three‐dimensional triboelectric nanogenerator (3D‐TENG) with a single electrode is designed, consisting of an outer transparent shell and an inner polyfluoroalkoxy (PFA) ball. Based on the coupling of triboelectric effect and electrostatic effect, the rationally developed 3D‐TENG can effectively scavenge ambient vibration energy in full space by working at a hybridization of both the contact‐separation mode and the sliding mode, resulting in the electron transfer between the Al electrode and the ground. By systematically investigating the output performance of the device vibrating under different frequencies and along different directions, the TENG can deliver a maximal output voltage of 57 V, a maximal output current of 2.3 μA, and a corresponding output power of 128 μW on a load of 100 MΩ, which can be used to directly drive tens of green light‐emitting diodes. Moreover, the TENG is utilized to design the self‐powered acceleration sensor with detection sensitivity of 15.56 V g‐1. This work opens up many potential applications of single‐electrode based TENGs for ambient vibration energy harvesting techniques in full space and the self‐powered vibration sensor systems.

A newly designed triboelectric nanogenerator (TENG) is demonstrated based on a contact-separation process between an Al foil and a finite size polyamide (PA) film. The working mechanism is based on charge transfer between the Al foil and ground. A 4×4 matrix of TENG array can be used for tracking motion by recording the output voltages signals in real-time to form a pressure map.

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. IntroductionOver the past decades, harvesting ambient environmental energy has attracted increasing interest for realizing self-powered systems and for meeting large-scale energy demands. Searching for clean and renewable energy with reduced carbon emissions is urgent to the sustainable development of human civilization. [ 1 ] To date, various energy harvesters for scavenging ambient environmental vibrational energy have been developed that rely on piezoelectric, [2][3][4][5][6] electromagnetic, [ 7,8 ] and electrostatic [ 9,10 ] transduction mechanisms. Considerable research effort has been devoted to improve the effi ciency of vibrational energy harvesters. [11][12][13][14][15][16][17][18] However, regardless of the transduction mechanisms and novel structures, the vibration-to-electric conversion effi ciency is still quite low in the existing harvesters because: 1) most of them are designed as linear resonant structures in order to achieve maximum power generation, which limits their application in realworld environments with stochastic or varying vibration spectra; [ 14 ] and 2) most devices can only effectively harvest vibrational energy from a single motion direction and/or within a small bandwidth. In this case, the harvesters are not effective at scavenging energy from a vibration with multiple or time-variant motion directions. [ 11,12,14 ] Recently, the innovative triboelectric nanogenerator (TENG) has offered a costeffective, simple, and robust approach to convert mechanical energy into electricity based on the coupling between triboelectrifi cation and electrostatic induction. [19][20][21][22][23][24][25][26][27] The triboelectrically charged planes of TENGs change the electric polarization and fi eld across two electrodes by either periodic vertical contact separation [19][20][21] or in-plane sliding, [ 22,23 ] leading to an alternating fl ow of electrons through the external load. The developed TENGs have been successfully applied as sustainable power sources for portable electronics, [ 21 ] magnetic sensors, [ 24 ] environmental monitors, [ 25 ] and other self-powered systems. [ 26,27 ] Here, we demonstrated a newly designed 3D-TENG that is able to scavenge vibrational energy in the out-of-plane direction and arbitrary in-plane directions with considerable wide bandwidth. It works in a hybridized mode of both vertical contact separation and in-plane sliding. Under out-of-plane motion excitation, the 3D-TENG produces an open-circuit voltage up to 123 V, a peak short-circuit current density of 30 mA m −2 , and a peak power density of 1.35 W m −2 . The corresponding electrical outputs are 143 V, 32 mA m −2 , and 1.45 W m −2 , respectively, when the 3D-TENG works under in-plane motion excitation. The remarkable performance enables the 3D-TENG to have tremendous practical applications including harvesting windor rain-droplet-induced vibrational energy from the national grid transmission lines, natural vibration energy from human walking, and rotation energy from vehicles with wheels.

We report the first flexible hybrid energy cell that is capable of simultaneously or individually harvesting thermal, mechanical, and solar energies to power some electronic devices. For having both the pyroelectric and piezoelectric properties, a polarized poly(vinylidene fluoride) (PVDF) film-based nanogenerator (NG) was used to harvest thermal and mechanical energies. Using aligned ZnO nanowire arrays grown on the flexible polyester (PET) substrate, a ZnO-poly(3-hexylthiophene) (P3HT) heterojunction solar cell was designed for harvesting solar energy. By integrating the NGs and the solar cells, a hybrid energy cell was fabricated to simultaneously harvest three different types of energies. With the use of a Li-ion battery as the energy storage, the harvested energy can drive four red light-emitting diodes (LEDs).