Bioinspired triboelectric droplet sensor for ammonia monitoring

Gas sensors with fast response are in high demand for environmental and health applications. Conventional solid-state sensing materials are inherently constrained by response delays arising from chemical bond transformations, posing significant challenges in overcoming response time lag. In this work, inspired by the alveoli of our respiratory system, we develop a triboelectric nanogenerator probe sensor driven by the formation of water droplets containing an air cavity, which incorporates NH3 molecules. The sensor achieves rapid response through instantaneous electron transfer at the liquid-solid interface, bypassing the need for gas adsorption and desorption on the surface of solid-state sensing materials. This hydro-electrochemical sensing mechanism achieves a response time of 1.4 s, surpassing that of most reported ammonia sensors. Through the integration of deep learning algorithms for optimization, the sensor demonstrates an ammonia detection accuracy of 96.2%. This study indicates a promising strategy for the rational design of gas sensors based on hydro-electrochemical sensing mechanisms. To address the challenge of response delays in gas sensors, this study proposes a hydroelectrochemical sensing strategy whereby droplets capture gas molecules and induce instantaneous interfacial electron transfer, enabling rapid detection.