Project description:Recently, triboelectric energy nanogenerators (TENGs) have been paid the most attention by many researchers to convert mechanical energy into electrical energy. TENGs usually have a simple structure and a high output voltage. However, their high internal resistance results in low output power. In this work, we propose a flexible triboelectric energy nanogenerator with the double-side tribological layers of polydimethlysiloxane (PDMS) and PDMS/multiwall carbon nanotube (MWCNT). MWCNTs with different concentrations have been doped into PDMS to tune the internal resistance of triboelectric nanogenerator and optimize its output power. The dimension of the fabricated prototype is ~3.6 cm(3). Three-axial force sensor is used to monitor the applied vertical forces on the device under vertical contact-separation working mode. The Prototype with 10 wt% MWCNT (Prototype I) produces higher output voltage than one with 2 wt% MWCNT (Prototype II) due to its higher dielectric parameter measured by LRC impedance analyzer. The triboelectric output voltages of Prototype I and Prototype II are 30 V and 25 V under the vertical force of 3.0 N, respectively. Their maximum triboelectric output powers are ~130 μW at 6 MΩ and ~120 μW at 8.6 MΩ under vertical forces, respectively.
Project description:Developing an eco-friendly, flexible and recyclable micro-structured dry electrode for sustainable life is essential. In this work, we have developed irregular, micro-structured sandpaper coated with graphite powder as an electrode for developing a simple, low-cost, contact-separation mode graphite-coated sandpaper-based triboelectric nanogenerator (GS-TENG) as a self-powered device and biomechanical sensor. The as-fabricated GS-TENG is a dielectric-conductor model. It is made up of a bottom layer with polytetrafluoroethylene (PTFE) as a triboelectric layer, which is attached onto a graphite-coated sandpaper-based electrode and a top layer with aluminum as another triboelectric layer as well as an electrode. The forward and reverse open-circuit voltages reach upto ~33.8 V and ~36.62 V respectively, and the forward and reverse short-circuit currents are ~2.16 µA and ~2.17µA, respectively. The output generated by GS-TENG can power 120 blue light-emitting diodes connected in series, liquid crystal display and can charge commercial capacitors along with the rectifier circuit. The capacitor of 22 µF is charged upto 5 V and is sufficient to drive digital watch as wearable electronics. Moreover, the device can track signals generated by human motion, hence it scavenges biomechanical energy. Thus, GS-TENG facilitates large-scale fabrication and has potential for future applications in wearable and portable devices.
Project description:Performance of triboelectric nanogenerators is limited by low and unstable charge density on tribo-layers. An external-charge pumping method was recently developed and presents a promising and efficient strategy towards high-output triboelectric nanogenerators. However, integratibility and charge accumulation efficiency of the system is rather low. Inspired by the historical development of electromagnetic generators, here, we propose and realize a self-charge excitation triboelectric nanogenerator system towards high and stable output in analogy to the principle of traditional magnetic excitation generators. By rational design of the voltage-multiplying circuits, the completed external and self-charge excitation modes with stable and tailorable output over 1.25 mC m-2 in contact-separation mode have been realized in ambient condition. The realization of the charge excitation system in this work may provide a promising strategy for achieving high-output triboelectric nanogenerators towards practical applications.
Project description:The rapid development of Internet of Things and artificial intelligence brings increasing attention on the harvesting of distributed energy by using triboelectric nanogenerator (TENG), especially the direct current TENG (DC-TENG). It is essential to select appropriate triboelectric materials for obtaining a high performance TENG. In this work, we provide a set of rules for selecting the triboelectric materials for DC-TENG based on several basic parameters, including surface charge density, friction coefficient, polarization, utilization rate of charges, and stability. On the basis of the selection rules, polyvinyl chloride, used widely in industry rather than in TENG, is selected as the triboelectric layer. Its effective charge density can reach up to ~8.80 mC m-2 in a microstructure-designed DC-TENG, which is a new record for all kinds of TENGs. This work can offer a basic guideline for the triboelectric materials selection and promote the practical applications of DC-TENG.
Project description:Cellulose-based triboelectric nanogenerators (TENGs) have gained increasing attention. In this study, a novel method is demonstrated to synthesize cellulose-based aerogels and such aerogels are used to fabricate TENGs that can serve as mechanical energy harvesters and self-powered sensors. The cellulose II aerogel is fabricated via a dissolution-regeneration process in a green inorganic molten salt hydrate solvent (lithium bromide trihydrate), where. The as-fabricated cellulose II aerogel exhibits an interconnected open-pore 3D network structure, higher degree of flexibility, high porosity, and a high surface area of 221.3 m2 g-1. Given its architectural merits, the cellulose II aerogel-based TENG presents an excellent mechanical response sensitivity and high electrical output performance. By blending with other natural polysaccharides, i.e., chitosan and alginic acid, electron-donating and electron-withdrawing groups are introduced into the composite cellulose II aerogels, which significantly improves the triboelectric performance of the TENG. The cellulose II aerogel-based TENG is demonstrated to light up light-emitting diodes, charge commercial capacitors, power a calculator, and monitor human motions. This study demonstrates the facile fabrication of cellulose II aerogel and its application in TENG, which leads to a high-performance and eco-friendly energy harvesting and self-powered system.
Project description:Usually, high temperature decreases the output performance of triboelectric nanogenerator because of the dissipation of triboelectric charges through the thermionic emission. Here, a temperature difference triboelectric nanogenerator is designed and fabricated to enhance the electrical output performance in high temperature environment. As the hotter friction layer's temperature of nanogenerator is 0 K to 145 K higher than the cooler part's temperature, the output voltage, current, surface charge density and output power are increased 2.7, 2.2, 3.0 and 2.9 times, respectively (from 315 V, 9.1 μA, 19.6 μC m-2, 69 μW to 858 V, 20 μA, 58.8 μC m-2, 206.7 μW). With the further increase of temperature difference from 145 K to 219 K, the surface charge density and output performance gradually decrease. At the optimal temperature difference (145 K), the largest output current density is 443 μA cm-2, which is 26.6% larger than the reported record value (350 μA cm-2).
Project description:The development of power generators that can function in harsh snowy environments and in contact with snow can be beneficial but challenging to accomplish. Herein, we introduce the first snow-based triboelectric nanogenerator (snow-TENG) that can be used as an energy harvester and a multifunctional sensor based on the principle of snow-triboelectrification. In this work, we used a 3D printing technique for the precise design and deposition of the electrode and triboelectric layer, leading to flexible, stretchable and metal-free triboelectric generators. Based on the single electrode mode, the device can generate an instantaneous output power density as high as 0.2 mW/m2, an open circuit voltage up to 8 V, and a current density of 40 μA/m2. In addition, the snow-TENG can function as a miniaturized weather station to monitor the weather in real time to provide accurate information about the snowfall rate, snow accumulation depth, wind direction, and speed in snowy and/or icy environments. In addition, the snow-TENG can be used as a wearable power source and biomechanical sensor to detect human body motions, which may prove useful for snow-related sports. Unlike conventional sensor platforms, our design works without the need for batteries or image processing systems. We envision these devices could potentially be integrated into solar panels to ensure continuous power supply during snowy weather conditions.
Project description:Harvesting biomechanical energy is an important route for providing electricity to sustainably drive wearable electronics, which currently still use batteries and therefore need to be charged or replaced/disposed frequently. Here we report an approach that can continuously power wearable electronics only by human motion, realized through a triboelectric nanogenerator (TENG) with optimized materials and structural design. Fabricated by elastomeric materials and a helix inner electrode sticking on a tube with the dielectric layer and outer electrode, the TENG has desirable features including flexibility, stretchability, isotropy, weavability, water-resistance and a high surface charge density of 250??C?m(-2). With only the energy extracted from walking or jogging by the TENG that is built in outsoles, wearable electronics such as an electronic watch and fitness tracker can be immediately and continuously powered.
Project description:To sustainably power electronics by harvesting mechanical energy using nanogenerators, energy storage is essential to supply a regulated and stable electric output, which is traditionally realized by a direct connection between the two components through a rectifier. However, this may lead to low energy-storage efficiency. Here, we rationally design a charging cycle to maximize energy-storage efficiency by modulating the charge flow in the system, which is demonstrated on a triboelectric nanogenerator by adding a motion-triggered switch. Both theoretical and experimental comparisons show that the designed charging cycle can enhance the charging rate, improve the maximum energy-storage efficiency by up to 50% and promote the saturation voltage by at least a factor of two. This represents a progress to effectively store the energy harvested by nanogenerators with the aim to utilize ambient mechanical energy to drive portable/wearable/implantable electronics.
Project description:Loss of tactile sensation is a common occurrence in patients with traumatic peripheral nerve injury or soft tissue loss, but as yet, solutions for restoring such sensation are limited. Implanted neuro-prosthetics are a promising direction for tactile sensory restoration, but available technologies have substantial shortcomings, including complexity of use and of production and the need for an external power supply. In this work, we propose, fabricate, and demonstrate the use of a triboelectric nanogenerator (TENG) as a relatively simple, self-powered, biocompatible, sensitive, and flexible device for restoring tactile sensation. This integrated tactile TENG (TENG-IT) device is implanted under the skin and translates tactile pressure into electrical potential, which it relays via cuff electrodes to healthy sensory nerves, thereby stimulating them, to mimic tactile sensation. We show that the device elicits electrical activity in sensory neurons in vitro, and that the extent of this activity is dependent on the level of tactile pressure applied to the device. We subsequently demonstrate the TENG-IT in vivo, showing that it provides tactile sensation capabilities (as measured by a von Frey test) to rats in which sensation in the hindfoot was blocked through transection of the distal tibial nerve. These findings point to the substantial potential of self-powered TENG-based implanted devices as a means of restoring tactile sensation.