Enhancing Conductivity in 3D Organic Electrochemical Transistors with PEDOT–Tetramethacrylate Integration

Electroconductive hydrogels offer a unique combination of conductivity and biocompatibility, mimicking the extracellular matrix for bioelectronic applications. Herein, we present a homogeneous, conductive, and cytocompatible hydrogel-based organic electrochemical transistor (OECT) composite, combining methacrylated gelatin (GelMA), PEDOT:PSS, and tetramethacrylated PEDOT:TOS (PEDOT-TMA:TOS). This three-component hydrogel overcomes challenges in PEDOT aggregation, low conductivity, and cytotoxicity. The hydrogel exhibited remarkable electrochemical performance with a five-order impedance reduction, sheet resistance of 1.53 kΩ sq –1, and conductivity of 2.9 S m –1 . OECTs fabricated with the hydrogel showed a threshold voltage of 0.216 V, transconductance of 2.1 mS, and an on/off ratio of 156.7. Live/dead assays confirmed excellent cytocompatibility due to efficient radical scavenging during cross-linking. This 3D conductive hydrogel network, compatible with cellular integration, establishes a foundation for next-generation bioelectronics, including sensors, neural interfaces, and tissue engineering.