Wireless plant stresses monitoring with a wearable chemiresistor gas sensor at room temperature

Plants are susceptible to biotic and abiotic stresses, they always make morphologic and metabonomic responses for self-preservation. The volatile organic compounds (VOCs) emissions generally change significantly in the face of different external stresses. In this study, an Au interdigital electrode (IDE) chemiresistor was induced to monitor the α-pinene vapor generated from Platycladus orientalis plants in real time to determine its external stress. The composite material of polyethylene-co-vinyl acetate (PEVA)/multi-walled carbon nanotube (MWCNT) was used as the sensitive film. The sensing material showed good selectivity and sensitivity (8.32 kΩ/ppm) with the detection limit of at least 0.5 ppm, and it was hardly affected by the relative humidity . In an actual test on the P. orientalis branch, the sensor resistance got about 15% increase to 4 mm-wide bark damage and 2% increase to 40-day water stress. The near field communication (NFC) tag was integrated with the Au IDE chemiresistor, which was used as a wireless and passive switch for plant stress monitoring. This study indicated that our developed α-pinene gas sensor worked steadily in laboratory tests, and it had the potential for wireless plant stress monitoring in the field.