Room-temperature, self-powered hydrogel-based flexible chemosensors for nitrogen dioxide detection enabled by...

The development of flexible gas sensors is of growing interest in wearable electronics. However, developing a gas sensor with low operating temperature, high sensitivity, and rapid response remains a huge challenge. Herein, we first develop a polyacrylamide-sodium acrylate-sodium citrate (PAM-Na-SC) hydrogel electrolyte, and design a hydrogel-based nitrogen dioxide (NO₂) gas sensor enabled by zinc-air batteries (ZABs). The device is continuously powered using the energy harvesting mechanism of ZABs. In this study, a systematic investigation was conducted on the gas-sensing performance of the PAM-Na-SC hydrogel electrolyte sensor. Furthermore, the gas-sensing characteristics of the sensor under different environmental conditions were explored, and the underlying sensing mechanism was elaborated in depth and detail. Under the conditions of room temperature (RT), 40 % humidity, a gas flow rate of 200 sccm, and NO₂ concentration of 50 ppm, this sensor exhibits exceptional performance, including ultrahigh sensitivity (1174 nA/ppm), ultrafast response/recovery times (16.6 s/4.5 s), ultra-low detailed limits of detection (LOD, 16.3 ppb), excellent selectivity, and long-term stability. This work provides a promising strategy for designing high-performance room-temperature, self-powered, and wearable gas sensors.