Ammonia ranks as the most typical biomarker in the analysis of exhaled breath. However, developing ammonia gas sensors remains challenging for noninvasive exhaled human breath monitoring. In this work, a polyaniline/bismuth oxychloride (PANI/BiOCl) heterojunction-inspired ammonia gas sensor was reported for real-time exhaled biomarker analysis. The PANI/BiOCl heterojunction-enabled gas sensor exhibits a very short response time (11 s), an ultralow limit of detection (0.5 ppm), a high response value (1.5%, even at 1 ppm), and excellent stability under ambient conditions. The intimate contact across the interface between BiOCl and PANI can greatly promote the charge carrier migration and separation. A wireless passive device was further developed by integrating a PANI/BiOCl heterojunction and a near-field communication tag, validating the feasibility of its use for expiratory disease monitoring. This work establishes an innovative pathway for the systematic development of high-performance wireless gas sensors.
Wang et al. (2026) studied this question.