Preparation of the Composite Yarn PEDOT:PSS/rGO/PAN/DL and Its Application in Sodium-Ion Detection

Effective farmland management requires real-time monitoring of plant growth status and timely response to stressors. To achieve this goal, we utilized wire organic electrochemical transistors (WECTs) to convert ion signals in plant vasculature into electrical signals in circuits, enabling the detection of ion concentrations. In our study, we employed a flexible substrate composed of a core-sheath structure nanofiber yarn impregnated with poly(3,4-ethylenedioxythiophene): polystyrene sulfonate (PEDOT:PSS) as a semiconductor channel. The gate was made of silver wire, while silver paste was sprayed at both ends of the core-sheath yarn to serve as a source and drain. This configuration allowed us to construct a wire organic electrochemical transistor that exhibited modulation performance and sensitivity at low voltages, with a transconductance of 1.07 × 10^–4 S. We conducted sodium ion concentration testing and successfully achieved the sensing of sodium ions at concentrations ranging from 10^–4 to 10^–1 M. This study lays the groundwork for the future development of organic electrochemical transistors in plants, enabling in situ detection of sodium ion concentrations under salt stress.