Raindrop falling, which is one kind of water motions, contains large amount of mechanical energy. However, harvesting energy from the falling raindrop to drive electronics continuously is not commonly investigated. Therefore, a self-cleaning/charging power system (SPS) is reported, which can be exploited to convert and store energy from falling raindrop directly for providing a stable and durable output. The SPS consists of a hydraulic triboelectric nanogenerator (H-TENG) and several embedded fiber supercapacitors. The surface of H-TENG is amphiphobic, enabling the SPS self-cleaning. The fiber supercapacitor which uses α-Fe 2 O 3 /reduced graphene oxide composite possesses remarkable specific capacitance, excellent electrical stability, and high flexibility. These properties of the fiber supercapacitor make it suitable for a wearable power system. A power raincoat based on the SPS is demonstrated as application. After showering by water flow, which simulates falling raindrops, for 100 s, the power raincoat achieves an open-circuit voltage of 4 V and lights a light-emitting diode for more than 300 s. With features of low cost, easy installation, and good flexibility, the SPS harvesting energy from the falling raindrop renders as a promising sustainable power source for wearable and portable electronics.
User-interactive electronic skin is capable of spatially mapping touch via electric readout and providing visual output as a human-readable response. However, the high power consumption, complex structure, and high cost of user-interactive electronic skin are notable obstacles for practical application. Here, we report a self-powered, user-interactive electronic skin (SUE-skin), which is simple in structure and low in cost, based on a proposed triboelectric-optical model. The SUE-skin achieves the conversion of touch stimuli into electrical signal and instantaneous visible light at trigger pressure threshold as low as 20 kPa, without external power supply. By integrating the SUE-skin with a microcontroller, a programmable touch operation platform was built that can recognize more than 156 interaction logics for easy control of consumer electronics. This cost-effective technology has potential relevance to gesture control, augmented reality, and intelligent prosthesis applications.
Self-powered electronic skin (E-skin) can be endowed with high robustness by employing self-healing materials. However, most self-powered E-skin employs two heterogeneous materials with high modulus mismatch at the interface and poor fully self-healing ability, which reduces the robustness of the whole device. Here, a conductive polyurethane elastomer (PUE) with excellent mechanical toughness and self-healing ability is prepared. Based on the self-healing insulated/conductive PUE homogeneous structure and triboelectric−electrostatic induction effect, a highly robust and selfpowered E-skin (HRSE-skin) is developed. The HRSE-skin possesses stable mechanosensation capability during the 50% stretching deformation due to a low modulus mismatch in the homogeneous structure. In addition, the stretchability and mechanosensation capability of the HRSE-skin can be restored after the fracture owing to the fully self-healing ability of the homogeneous structure. Therefore, the HRSE-skin has high robustness of the whole device including stable service behaviors and excellent restorability. The developed HRSE-skin demonstrates high robustness in the detection of the force and bending angle of the prosthetic joint. This work solves the low robustness of self-powered E-skin by the preparation of conductive selfhealing PUE and the construction of the homogeneous structure, which is important for the practical applications of selfpowered E-skin in prosthetic limbs and advanced robotics.
Triboelectric nanogenerators (TENGs) have recently been invented as a potential energy technology for harvesting low‐frequency mechanical energy. The load power acquired from a TENG is far less than the maximum output power of the TENG for the large internal impedance and impedance mismatch, and this difference results in an extremely low energy transmission efficiency. Here, a universal strategy is proposed for improving the energy transmission efficiency and load power through dielectric material design, including a reduction in the effective thickness and the directional alignment of the electric dipole. This strategy reduces the internal impedances of TENGs with different modes and results in the improvement of energy transmission efficiency and load power. According to this strategy, the internal impedance of an as‐fabricated TENG is reduced from 16 to 1.3 MΩ, and the energy transmission efficiency is enhanced from 22.46% to 99.5%. Moreover, the load power under 1 MΩ resistance is improved from 0.014 to 0.251 µW, an increase of 18 times. The strategy not only opens a universal and new road to power management, but also paves the way for the industrial applications of TENGs.
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