Frequency-independent self-powered sensing based on capacitive impedance matching effect of triboelectric nanogenerator

The advance of intelligent Internet of Things (IoT) requires a large number of independent sensors, while the power supply of the sensors has hindered its development. In this work, we present a concept of frequency-independent self-powered sensing technology based on the capacitive impedance matching effect of triboelectric nanogenerator (TENG). When the intrinsic capacitance of the TENG is constant and matched with an external capacitive load, the output voltage is only related to the external capacitive load and not affected by the working frequency of TENG. In a proposed system, the output voltage of a vertical contact-separation TENG distinctly changes from ~140 V to ~5 V only with a load capacitance ranging from 10 pF to 10 nF, while the voltage does not change at different moving frequencies in a wide range. By replacing the external capacitive load with a glycerol-droplet based capacitive temperature sensor, both quantifiable temperature sensing and frequency-independent high temperature alarming system can be realized. Significant progresses in broad selectivity for sensing materials and high reliability under different motion frequencies are present in this self-powered sensing system, revealing the promising application prospects in intelligent wearable sensing electronics.