Power generation humidity sensor based on NaCl/halloysite nanotubes for respiratory patterns monitoring

The power generation humidity sensor has received great attention, however, how to improve its humidity sensing performance (e.g., detection range and response speed) is still facing many challenges. Herein, we propose a simple power generation humidity sensor using NaCl as electrolyte and halloysite nanotubes (HNT) as humidity sensing material. The results show that the introduction of HNT can significantly improve the humidity sensing performance of the humidity sensor based on bare NaCl electrolyte. Specifically, the NaCl/HNT humidity sensor has a wide detection range (10.9 −91.5% relative humidity (RH)), short response time (11.3 s), and good repeatability (20 cycles). The output voltage of the NaCl/HNT humidity sensor reaches 0.537 V at 91.5% RH, and the corresponding maximum power is 1.56 μW. In addition, the NaCl/HNT humidity sensors with series integration can charge the capacitor at high humidity, and the NaCl/HNT humidity sensor can be used for monitoring respiratory patterns. This work provides a useful strategy for fabricating high-performance power generation humidity sensor.