Silver(i) bipyrazolates as room-temperature chemoresistive sensors for ethylene determination

Ensuring food freshness and safety along the agri-food industrial supply chain is a major priority. Five chemoresistive sensors based on AgI bipyrazolate thin films were developed and tested at room temperature against 20–300 ppm volatile organic compounds released during fruit ripening (ethylene, ethanol, methanol, ethyl acetate, and acetaldehyde), or substances present in fruit storage chamber atmospheres (water vapor and carbon dioxide). Ag2Et4BPZ (H2Et4BPZ = 3,3′,5,5′-tetraethyl-1H,1H′-4,4′-bipyrazole) showed the most promising outcomes as a selective ethylene sensor, successfully combining the highest sensitivity, impressive response and recovery times (25 and 127 s, respectively), short-term repeatability (up to 7 cycles), long-term stability (up to 100 days), and limited influence of relative humidity. The practical applicability of the Ag2Et4BPZ-based sensor was confirmed by real-time monitoring of ethylene levels in a simulated multi-analyte storage chamber during plum ripening. These encouraging results pave the way for further exploration of AgI bipyrazolates as room-temperature, selective chemoresistive sensors in the strategic agri-food industrial context.