Bio-inspired hierarchical GO/WS₂/PANI heterostructure for high-performance room-temperature NH₃ sensing: Enabling real-time wireless health monitoring

Exhaled ammonia (NH₃) is a key biomarker for kidney and metabolic diseases, and its low-concentration detection at room temperature can facilitate early disease screening and enable remote patient care. However, conventional NH₃ sensors are hindered by insufficient sensitivity, poor flexibility, and unsustainable fabrication. Herein, we report a functionally bio-inspired hierarchical strategy by constructing a ternary GO/WS₂/PANI heterostructure that translates key functional principles of the human olfactory epithelium—humidity-enabled enrichment, interfacial coupling, and multiscale transport. A flexible and environmentally friendly sensor was fabricated via vacuum filtration and inkjet printing onto cellulose paper. The sensor exhibits a high response of 170 % toward 10 ppm NH₃ at room temperature, with response and recovery times of 13 and 26 s, and a detection limit of 81 ppb. Density functional theory calculations reveal that enhanced sensing performance arises from heterojunction-induced charge redistribution and favorable band alignment. Moreover, the device demonstrates excellent selectivity and operational stability. A wireless sensing module was further integrated, enabling real-time detection of exhaled NH₃ and emissions from urine and feces. This work presents a novel biomimetic design paradigm for next-generation wearable gas sensors, with broad potential for applications in health monitoring, early disease screening, and telemedicine.