A battery-free music-driven humidity sensor for intelligent wearable sensing system in smart diaper


 The potential intelligent multifunctional diaper with the integration of flexible sensors and data processing/transmitting units may have the functions of monitoring the urination of baby, detecting the physiological parameter and transmitting the information to the mobile terminal of their parents. Here, we present a battery-free music-driven humidity sensor for intelligent wearable sensing system in smart diaper. The working mechanism is based on the coupling of triboelectric effect and humidity sensing process. Under the driving of baby-acceptable music sound, the two layers of the device vibrate (resonance effect), and the triboelectric effect can generate electrical output. The output decreases with increasing humidity, acting as both the power source and humidity sensing signal. The sensor can be embedded in a diaper to monitor the urination of baby, and a wireless transmitter is integrated in the system for uploading the information. The present results can promote the development of next generation of self-powered active sensors and expand the scope of battery-free sensing system.