High-performance electrochemical power generation humidity sensor based on NaCl/sodium alginate humidity sensing electrolyte and Cu/Zn electrodes for visual humidity indication and respiratory patterns detection

Electrochemical power generation humidity sensors have received great attention recently, but it is challenging for achieving good humidity sensing and power generation performances simultaneously. Herein, we construct a high-performance power generation humidity sensor based on NaCl/sodium alginate (SA) humidity sensing electrolyte and Cu/Zn electrodes. Benefiting from the reasonable selection of humidity sensing electrolyte and electrode materials and the design of sensor structure, the optimized NaCl/SA humidity sensor exhibits wide humidity sensing detection range (10.9−91.5% relative humidity (RH)), short response time (5.6 s), and good repeatability (20 cycles) at 25°C. Importantly, the humidity sensor has high response voltage (~0.7 V), large short circuit current (~24 μA) and loading power (~2.63 μW) at 91.5% RH. The NaCl/SA humidity sensor can be used for passive visual humidity indication by connecting it to a pointer microammeter. In addition, we designed signal processing circuit and software program to recognize respiratory patterns using NaCl/SA humidity sensor. This work not only achieves a high-performance electrochemical humidity sensor, but also provides a useful reference for its applications in passive visual humidity and respiratory patterns detections.