DIW Printing of PEDOT:PSS on Living Plants for Biohybrid Systems

Global agriculture faces mounting stressors including drought, flooding, and pathogen infection, yet methods to noninvasively monitor plant health remain limited. Plant biohybrids aim to address this by merging soft, flexible conductive materials with living systems. However, achieving stable, biocompatible interfaces on dynamic, nonplanar leaf surfaces remains a challenge. This paper hypothesizes that in situ printing of conductive polymers on a leaf surface will broaden the scope of plant biohybrids and compares a commercial PEDOT:PSS versus a softer and stretchable PEDOT, where PSS is replaced with a soft block polymer. To test this, shear-thinning conductive polymer inks (∼10³ Pa·s) were formulated for both polymers and printed directly onto leaves with direct ink writing (DIW). Biocompatibility and tissue integrity were evaluated through reactive oxygen species (ROS) assays, chlorophyll measurements, and SEM imaging, confirming minimal stress and preservation of microstructures such as trichomes. Importantly, the prints remained intact for over 28 days with relatively low drops in conductivity over 2 weeks. This noninvasive approach expands opportunities in plant-based biosensing, environmental monitoring, and biohybrid technologies.