Biopotential Measurement of Plant Leaves with Ultra-Light and Flexible Conductive Polymer Nanosheets

Abstract This study demonstrates the feasibility of free-standing conductive polymer nanosheets (referred to hereafter as “conductive nanosheets”) as bioelectrodes for plant leaves. The conductive nanosheet exhibited ultra-conformability and physical adhesion to unevenly structured surfaces, such as the veins of a plant leaf, without the use of chemical glue, owing to the ultra-thin and light structure (300 nm thick, 150 µg). The conductive nanosheet coupled with a Bluetooth system enabled wireless biopotential measurement of plant leaves (Angelica keiskei Koidzumi) up to approximately 1500 h, while conventional bioelectrodes such as pre-gel electrodes caused discoloration during the measurement, owing to the acrylic glue utilized for adhesion. We also discovered that the biopotential pattern was altered under periodic light-emitting diode (LED) irradiation. Such minimally invasive measurements using the conductive nanosheets can pave the way for a revolutionary method to analyze the bioactivity of plants in the application of agriculture and food science.