Self-Powered Flexible Humidity Sensor with Power Generation and Multifunctional Applications

Self-powered devices are extremely attractive in the field of wearable electronics because of their simplified structure and zero power consumption. Combining the humidity sensor principle and the electrolyte composition in primary battery, a self-powered and simple-structured humidity sensor was prepared by applying poly(vinyl alcohol)/SiO2 nanoparticles/sodium carboxymethylcellulose composite as the sensing film. Conductive Cu tape and Al tape were adhered on two sides of the sensing film and acted as the electrodes. The proposed humidity sensor was tested for its self-powered sensing property under different operating conditions. In particular, the humidity sensing mechanism of the composite film was investigated in detail by the complex impedance spectra and phase angle spectra. Multifunctional applications of the sensor for power generation, breath monitoring, distance sensing, and skin moisture detection were demonstrated. The simple-structured, low cost, and self-powered characteristics of the presented humidity sensor provide an effective way to develop a flexible humidity sensor that can be used for wearable electronics and other fields.