Wearable, Breathable, and Wireless Gas Sensor Enables Highly Selective Exhaled Ammonia Detection and Real-Time Noninvasive Illness Diagnosis
Haipeng Dong, Xiaowei Li, Xiaowei Li, Yu Liu, Wanying Cheng, Chaohan Han, Yunpeng Yin, Xinghua Li, Xinghua Li, Changlu Shao, Yichun Liu
Abstract
Wearable gas sensors capable of real-time analysis of exhaled breath have been identified as ideal devices for noninvasive illness diagnosis. However, due to their inherent rigidity and brittleness, as well as high cross-sensitivity, conventional semiconductor gas sensors face significant challenges in achieving high flexibility, robustness, and selective exhaled breath analysis. Herein, we propose a wearable gas sensor by anchoring a SnS 2 nanosheets/polyaniline (PANI) sensing layer in situ onto a permeable and flexible yttria-stabilized zirconia (YSZ) nanofiber substrate for the analysis of exhaled NH 3 . The cross-linked meshes of the YSZ network and the abundant voids between SnS 2 nanosheets effectively release the stress concentration in YSZ/SnS 2 /PANI films, enabling the sensor to withstand severe folding/bending deformation. The organic PANI sheath endows the YSZ/SnS 2 /PANI-based gas sensor with enhanced toughness (0.66 kJ·m –3 ), stable electrical connection, and excellent robustness. The unique protonation/deprotonation sensing mechanism, coupled with the heterojunction effect of the sensing layer, ensures outstanding selectivity (sensor immunity coefficient ≈ 69%) and a high response to NH 3 . To support wearable applications, the sensing signals from the wearable sensor are transmitted wirelessly via Bluetooth and displayed on a smartphone. This work greatly advances the application of a wearable semiconductor sensor in personal disease diagnosis.