A plant-receptor-inspired cuprous complex for wearable trace-level ethylene gas sensing

Ethylene (C₂H₄) functions both as a key phytohormone regulating plant growth and development and as an essential feedstock in organic chemical synthesis. Reliable detection of C₂H₄ is critical for monitoring emissions during crop cultivation and ensuring safety in industrial transportation. However, most existing C₂H₄ sensors rely on noble-metal catalysts and/or high-operating temperature, which significantly constrain their practical applications. Moreover, achieving high specificity in C₂H₄ recognition remains a major challenge. Inspired by the signal transduction mechanism of plant C₂H₄ receptor, this study propose a biomimetic sensing strategy based on a facilely synthesized cuprous-cystine complex (Cu₂Cyt), which features a sulfur-bridged Cu⁺ coordination center that mimics the biological binding site for C₂H₄ recognition. The noble-metal-free wearable sensor was fabricated by depositing a Cu₂Cyt/MXene composite onto a flexible interdigital electrode, enabling room-temperature detection of C₂H₄ emitted from fruits or leaked from transport pipelines of chemical industries. It exhibits a detection range (0.05-5 ppm), an ultra-low detection limit of 1.07 ppb, fast response/recovery (51/92 s), high sensitivity of 3.64%·ppm^-1 in trace concentration range of 0-0.5 ppm, and good reversibility and reproducibility. Overall, this work offers a bioinspired design strategy for low-cost, high-performance, noble-metal-free, and wearable sensors, capable of trace-level C₂H₄ monitoring.