Rapid Self-Driven Formation of Conducting Polymers for Bioelectronics.

<title>Abstract</title> <p>Organic mixed ionic-electronic conductors (OMIECs) are pivotal for next-generation organic electronics and bioelectronics. However, conventional fabrication methods such as electrochemical and chemical polymerization, and spin-coating often involve complex, multi-step processes, specialized equipment, time-consuming patterning, and significant energy input. Here, we overcome these limitations by introducing a self-driven polymerization method, in which an OMIEC precursor molecule undergoes direct oxidation on a metal electrode. This simple, equipment-free approach enables rapid, in situ formation of conducting polymer coatings on a range of noble metal surfaces, including challenging architectures. This method enables one-step formation of high-performance organic electrochemical transistors with simultaneous glucose oxidase integration, directly producing a functional glucose biosensor and highlighting its potential for multifunctional devices. Importantly, we validate the performance of these high-capacitance coatings in a soft multielectrode array cuff for sciatic nerve interfacing, achieving selective electrical stimulation and high-fidelity in vivo recording. The device supports motor-selective stimulation, ultra-low stimulation saturation thresholds (25–30 µA), and reliable detection of sensory compound action potentials across multiple plantar hind paw regions. Overall, this fast, scalable, and aqueous-based approach provides a high-throughput route for fabricating advanced bioelectronic devices.</p>