Wireless Detection of Biogenic Amines Using a Split-Ring Resonator with Silver Nanoparticles-Decorated Molybdenum Disulfide

Safety associated with ammonia requires the development of gas sensors for various applications, including food spoilage detection and livestock farming management. Radio-frequency identification (RFID) is a promising technology to fabricate a wireless gas sensor for remote concentration readouts. However, most of the reported RFID-enabled gas sensors determined the analyte concentration by using the reflection coefficient (S₁₁) of sensor tag as an indicator, which was prone to be disturbed by measurement variations and external disturbances. Herein, we reported a wireless gas sensor with high tolerance to measurement variations through recognizing the resonant frequency (f) of sensor tag, enabling reliable detection of ammonia and various biogenic amines in real time. Compared with other conducting 2D materials, molybdenum disulfide (MoS₂) exhibits tunable semiconducting properties and high specific surface area, which can serve a promising candidate for RFID-based gas sensors. By immobilizing silver nanoparticles-decorated molybdenum disulfide nanosheets (Ag@MoS₂) on a nested split-ring resonator (SRR), the SRR sensor tag exhibited significant f downshifts at increasing ammonia concentrations, featuring with high sensitivity to ammonia (0.097 ppm^–1, based on relative f changes), low detection limit (<1 ppm), and fast response time. Furthermore, our wireless gas sensor enables early detection of biogenic amines from meat spoilage and animal excrements. Finally, we installed our wireless sensors at a poultry farm with chicken flock>10,000 to provide reliable readouts of localized concentrations of biogenic amines.