Robust, Stretchable, and Flexible Polymer Nanofiber-Based Wearable Platform for Colorimetric and Chemiresistive Dual-Mode Ammonia Gas Sensing

Abstract

Ammonia (NH3) is the second-most-produced chemical worldwide and has numerous industrial applications. However, such applications pose significant risks, as evidenced by human casualties caused by NH3 leaks or poisoning in confined environments. This highlights the critical need for highly portable and intuitive wearable NH3 sensors. The chemiresistive sensors are widely employed in wearable devices due to their simple structure, high sensitivity, and short response times, but are prone to malfunctioning and inaccurate gas detection because of the corrosion or failure of the sensing material under the influence of humidity, high temperatures, and interfering gas species. Addressing these limitations, a gas-sensing platform with a polymer-based nanofiber structure has been developed, providing flexibility and facilitating efficient transport of NH3 between the colorimetric (bromocresol-green-based) and chemiresistive (poly(3,4-ethylene dioxythiophene):poly(styrene sulfonate)-based) sensing layers. This dual-mode design enables reliable NH3 detection. The NH3-sensing performance of each individual layer is comparable to that of the dual-mode gas-sensing platform, which operates effectively even when attached to human skin and in humid environments. Therefore, this study establishes a robust, selective, and reproducible NH3 sensor for diverse applications and introduces an innovative sensor engineering paradigm.