A Photo‐Patternable Solid‐State Electrolyte for High‐Performance, Miniaturized, and Implantable Organic Electrochemical Transistor‐Based Circuits

Abstract

Abstract Organic electrochemical transistors (OECTs) are crucial for next‐generation (bio‐)electronic devices but are often constrained by the use of aqueous electrolytes, which introduce crosstalk, hinder miniaturization, and limit circuit integration. Here, a photo‐patternable solid‐state electrolyte based on 𝜄‐carrageenan (𝜄‐CGN) and poly(ethylene glycol) diacrylate (PEGDA) is presented, enabling high‐performance OECTs and complementary circuits. The 𝜄‐CGN electrolyte exhibits high ionic conductivity (>10 mS cm −1 ), comparable to a 0.1 m NaCl aqueous electrolyte, while supporting precise patterning down to 15 µm, fast transient response times, minimal hysteresis, and excellent stability in both p‐ and n‐type OECTs. Compact solid‐state NAND/NOR gates (500 × 800 µm 2 ), 4‐input NAND gates (1600 × 800 µm 2 , 8 OECTs), and half‐adders (2 × 1 mm 2 , 18 OECTs) are demonstrated, all exhibiting correct logic functions and low‐voltage operation. To highlight its potential for implantable bioelectronics, solid‐state spiking circuits, monolithically integrated with flexible cuff electrodes, are developed for vagus nerve stimulation in mice. These findings establish 𝜄‐CGN‐based solid‐state electrolytes as a promising platform for scalable, implantable circuits, paving the way for next‐generation bioelectronic devices.