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

Abstract

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.