A battery-less self-powered dual-parameter omnidirectional wireless sensing system based on symmetrical resonant circuit

Current wireless sensing systems mainly rely on batteries as power source, which requires extensive maintenance resources. Battery-less self-powered wireless sensing system is a promising technology to solve this problem with real-time sensing capability. However, most of the systems can not simultaneously achieve multi-parameter omnidirectional wireless sensing with high sensing stability, and adequate transmission distance. Here, a self-powered dual-parameter omnidirectional wireless sensing system is proposed. By utilizing a compact symmetrical resonant circuit, pulsed output of a triboelectric nanogenerator can be modulated into a decaying resonant signal with two resonance frequencies that are independently correlated to variations of the sensors. The decaying resonant signal is then transmitted through a spark microswitch wirelessly and omnidirectionally with a distance well over 5m. Compared with previous works, the proposed system shows the most comprehensive capabilities encompassing omnidirectional wireless transmission, multi-parameter sensing, high sensing stability, and long transmission distance at the same time. A preliminary humidity/liquid level dual-parameter wireless sensing demonstration is conducted, and the sensors exhibits high sensing accuracy and stability, showing its great potential for applications.