Implantable Ion-Selective Organic Electrochemical Transistors Enable Continuous, Long-Term, and In Vivo Plant Monitoring.

The development of plant-specific biosensors holds the potential to uncover new insights into plant physiology and advance precision agriculture. Current sensing platforms mainly focus on broad plant phenotypes (e.g., elongation and hydration) and local environmental monitoring (e.g., temperature and moisture). Here, an ion-selective organic electrochemical transistor (IS-OECT) is introduced that enables real-time monitoring of variations in potassium ion concentration within the xylem of pine trees. This work demonstrates that the high sensitivity of the IS-OECT enables the detection of subtle variations in potassium ion concentrations in the xylem sap of living trees, and the high stability of the sensor allows for in vivo measurements over five weeks. Furthermore, the implantable sensors are fabricated using processes that are compatible with low-cost manufacturing (i.e., lithography-free). This sensing technology, therefore, has great potential to be a game-changer in precision forestry and could extend to precision agriculture and horticulture practices.