Triboelectric nanogenerators (TENGs) exhibit great application potential in the fields of intelligent sensing and Internet of Things terminal devices due to their advantages of self-powering, simple structure, and high sensitivity. A self-powered alarm sensor for smart manhole covers is proposed to realize real-time monitoring of water immersion and abnormal displacement without external power supply. Experimental results show that the sensor can generate distinguishable voltage signals under water immersion and different displacement states, enabling rapid recognition of potential hazards such as manhole cover offset and accumulated water. On this basis, a reliable intelligent alarm system is constructed, which can receive, analyze, and warn of abnormal signals in real time. Therefore, it can even directly replace commercial manhole covers, demonstrating the broad application prospects of TENG in the field of intelligent monitoring. With the continuous advancement of TENG technology, the functions of this manhole cover alarm will be further expanded and optimized in the future, providing stronger support for the construction of smart cities.
Cha et al. (Sun,) studied this question.