Highly sensitive and fast response/recovery ammonia sensor based on PANI/LIG at room temperature

Real-time and accurate detection of ammonia in the environment provides timely alarm for excessive exposure or food spoilage. However, metal oxide-based ammonia gas sensors often need to operate at high temperatures (200–400℃) and conductive polymer-based ammonia gas sensors suffer from long response/recovery time, which are challenging for real-time wearable applications. Meanwhile, three-dimensional porous laser-induced graphene (LIG) features simple preparation, high carrier mobility, good conductivity, and large specific surface area, presenting opportunities to further combine with conductive polymers for enhanced performance. This work reports a highly sensitive and selective, room-temperature ammonia sensor with fast response/recovery based on polyaniline (PANI)/laser-induced graphene (LIG) composite fabricated by one-step laser direct writing with spraying. The sensor with optimized composite ratio and operating conditions exhibits a large response of 68 % to 60 ppm ammonia with a rapid response/recovery time of 53/167 s, together with a demonstrated detection limit of 5 ppm. Together with the miniaturized data acquisition module and integrated APP, the integrated wireless ammonia detection system demonstrates the capability to accurately detect the ammonia concentration in real time for meat preservation, health protection, and smart agriculture.