Siphon self-powered water level warning system with energy harvesting function based on triboelectric nanogenerators

Water level monitoring is crucial for early warning and automatic alarming of floods. As climate change causes floods to become more frequent and severe, it is urgent to develop novel water level sensing and warning systems to mitigate economic and social losses. This work proposes a siphon self-powered water level warning system with an energy harvesting function based on triboelectric nanogenerators (TENGs). Specifically, a siphon unit with multistage siphon pipes is designed to convert the water level height information and water level potential energy into outlet flow rate information and water flow kinetic energy, respectively, which are then converted by a sensing and power generation cooperation unit into the frequency information and electrical energy. The presented water level sensing principle is based on linear relationship between frequency and water level, providing centimeter-level resolution and excellent stability in various humidity environments. Besides, rotational triboelectric nanogenerator (R-TENG) combined with the siphon unit transforms high-entropy water level potential energy into low-entropy steady electrical energy, achieving maximum voltage of 400 V and power of 2.9 mW. Furthermore, demonstration experiments show the system functions of water level sensing and early warning. This TENG-based water level warning system holds significant potential for developing self-powered flood warning wireless sensing networks.