Flexible Printed Gel Electrodes: Towards Living Plant Sensors for Nature-Based Environmental Monitoring

Interfacing bioelectronic devices with plants can enable nature-based sensing networks through transduction of self-generated electrical signals from living plant nodes 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(3,4ethylenedioxythiophene) 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. Compared to commercial Ag/AgCl electrodes, the developed bioelectrodes provide higher sensitivity, faster signal dynamics, and comparable signal-to-noise ratios. The adhesive gel electrodes maintain low impedance over extended periods, which is critical for long-term monitoring bioelectronic signals. Low impedance and robust connection to the plant tissue enabled the tracking of diurnal changes. This stability enabled real-time monitoring of a Venus flytrap’s response to environmental factors such as temperature variations and insect activity. 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.