Long-term On-Leaf Monitoring of Plant Electrophysiology with Printed Adhesive Gel Bioelectrodes

Interfacing bioelectronic devices with plants can enable nature-based sensing networks by transducing electrical signals from living plants into real-time environmental data. A key challenge in developing such platforms is to create stable, biocompatible electrodes that provide sufficient adhesion to plant tissue with minimal impedance drift. In this report, an adhesive gel electrode featuring an inkjet-printed poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS) trace on a poly(vinyl alcohol) (PVA) hydrogel substrate with a methyl cellulose adhesive is presented. When attached to the inside of a Venus flytrap (Dionaea muscipula) lobe these biocompatible printed conformable electrodes demonstrate long-term mechanical stability and reliable continuous recording of action potentials, including when removed and reattached over 14 days. Compared to rigid Ag/AgCl electrodes, these bioelectrodes provide higher sensitivity, faster signal dynamics, and comparable signal-to-noise ratios. The gel electrodes maintain low impedance over extended periods (120 hrs), which is critical for long-term monitoring of bioelectronic signals. This stability enabled real-time monitoring of a Venus flytrap's response to environmental factors such as temperature variations, insect activity, and diurnal variations. Additionally, the bioelectrodes were integrated with low-cost ESP32 microcontroller-based electronics, enabling wireless plant-to-plant communication over long distances. This system demonstrates a biologically integrated platform for developing nature-integrated networks that utilize living plants as sensor nodes.