Paper-based laser-scribed graphene towards wearable plant sensor: A portable electrochemical platform for precision...

A wearable plant sensor, developed on an eco-friendly substrate, is designed for non-destructive, in-situ, and real-time pesticide analysis on plants and fruits. In this study, we introduce a wearable plant sensor fabricated on a paper substrate using the laser-scribed graphene (LSG) technique for the detection of the pesticide paraquat (PQ) in crops. A synergistic effect was observed from the combination of colorless nail polish and the chemically treated paper substrate, leading to the formation of porous, high-performance, conductive graphene-based electrodes via the LSG fabrication process. The device detects PQ by square wave voltammetry (SWV) at concentrations ranging from 0.5 to 100.0 μmol L^-1 in a 0.1 mol L^-1 Britton-Robinson (BR) buffer (pH 9.0), with a limit of detection (LOD) of 0.082 μmol L^-1. The wearable plant sensor demonstrated excellent mechanical durability under repeated bending cycles, simulating real-world conditions on crops. Furthermore, it showed remarkable selectivity in the presence of commonly used pesticides and molecules typically found in natural beverage samples derived from fruits. As proof of applicability, the flexible and sustainable non-enzymatic wearable sensor was applied directly to the surfaces of fruits and leaves to detect PQ using a portable potentiostat and a smartphone. The results confirm its suitability for on-site pesticide detection, making it an effective tool for precision agriculture (PA) applications.