All-MXene-Printed RF Resonators as Wireless Plant Wearable Sensors for In Situ Ethylene Detection

Printed flexible electronics have emerged as versatile functional components of wearable intelligent devices that bridge the digital information networks with biointerfaces. Recent endeavors in plant wearable sensors provide real-time and in situ insights to study phenotyping traits of crops, whereas monitoring of ethylene, the fundamental phytohormone, remains challenging due to the lack of flexible and scalable manufacturing of plant wearable ethylene sensors. Here the all-MXene-printed flexible radio frequency (RF) resonators are presented as plant wearable sensors for wireless ethylene detection. The facile formation of additive-free MXene ink enables rapid, scalable manufacturing of printed electronics, demonstrating decent printing resolution (2.5% variation), ≈30000 S m^-1 conductivity and mechanical robustness. Incorporation of MXene-reduced palladium nanoparticles (MXene@PdNPs) facilitates 1.16% ethylene response at 1 ppm with 0.084 ppm limit of detection. The wireless sensor tags are attached on plant organ surfaces for in situ and continuously profiling of plant ethylene emission to inform the key transition of plant biochemistry, potentially extending the application of printed MXene electronics to enable real-time plant hormone monitoring for precision agriculture and food industrial management.