Wireless Self-powered Humidity Sensor System Based On Triboelectric Nanogenerator

At present,the energy harvesting technology of Triboelectric Nanogenerator(TENG)is getting mature,and the scheme of using TENG to supply energy for wireless sensor networks shows great potential for application.Therefore,this paper proposes a wireless self-powered humidity sensing system based on a friction nanogenerator without any chip or active device.The TENG in the system provides energy for the sensing system,uses a capacitive humidity sensor and an inductor to form an LC resonant circuit,and transmits the humidity signal wirelessly in the form of electromagnetic waves,which can receive the sensor signal by coil coupling to realize the detection and wireless transmission of humidity sensing signal.Firstly,based on Maxwell’s equations,the generator theory of TENG is analyzed and the theoretical model of TENG’s power generation is derived.COMSOL software is used to perform finite element simulation analysis of both horizontal and vertical frictional power generation,and then this paper design vertical contact frictional nano-generators,and determine the energy supply scheme of wireless self-powered humidity system.Next,the TENG structure and energy storage management circuit are optimized,and the TENG structure and energy storage circuit are designed by combining the high instantaneous energy output characteristics of the vertical contact TENG.Compare the charge confinement ability of different materials and determine the materials for TENG preparation.Optimize the surface microstructure of the material and increase the effective contact area during friction.Design the TENG rebound structure to increase the contact separation speed and enhance the output voltage of the TENG.Design fractal-design switched-capacitor-converter(FSCC)to improve the output current of TENG.Build a test platform to compare the power generation capacity before and after optimization.Then,design the wireless sensing system based on LC resonant circuit.The TENG limit trigger structure is used to ensure that the TENG equivalent capacitance value remains constant during the humidity sensing process,eliminating its influence on the humidity sensing accuracy.Derive the equivalent circuit model and verify the validity of the model through experiments.The factors affecting the wireless signal transmission distance are analyzed,and the design parameters of the circuit are optimized.Finally,the experimental platform of humidity sensing system is built to receive the wireless humidity sensing signal electromagnetic wave by coil coupling.Extract the frequency information of the signal by fast Fourier transform,calibrate the self-powered wireless humidity sensing signal by standard humidity signal.Perform linear fitting of the frequency information of humidity,conduct periodic and step humidity change experiments.And determine the stability and repeatability of the sensor in the 20% RH-80%RH range with a sensitivity of 1.26 k Hz/%RH.