Adaptive Liquid-Level Sensor Based on a Dual-Mode Triboelectric Nanogenerator

Liquid-level sensors are widely employed for monitoring and alarming liquid levels in storage tanks and vessel compartments. They are essential in promptly comprehending the container’s liquid-level status. In this study, an adaptive dual-mode triboelectric nanogenerator is proposed for real-time liquid-level monitoring. It is the combination of liquid–solid contact separation electrification and solid–solid contact electrification that forms the working mode of the studied liquid-level sensor. In contrast to the single operating mode of the liquid–solid contact separation triboelectric nanogenerator, the studied device provides additional output from solid–solid contact electrification. Unlike the single liquid–solid triboelectric nanogenerator, the output of the adaptive dual-mode triboelectric nanogenerator will not decline with ion concentrations in the liquid medium. Monitoring the open-circuit voltage signal reveals a correspondence between the signal and the liquid-level oscillation. Therefore, open-circuit voltage can be used to indicate liquid-level variations in real time.