Architecting Organic Electrochemical Transistors for Bioelectronics: From Channel Micro‐Engineering to Microarray Systems

Organic electrochemical transistors (OECTs) have emerged as transformative devices that revolutionize next‐generation electronics to bridge ionic/electronic signaling at the interface between biological and microelectronic systems. This review systematically explores fundamental breakthroughs in OECT channel material engineering and device manufacturing across micro/nanoscales for emerging bioelectronic systems, emphasizing microarchitecture design and patterning strategies that unlock advantages including enhanced transistor performance, high speed, improved mechanical durability, high‐fidelity integration, as well as biocompatibility. We first briefly introduce the device physics underpinning OECTs and state‐of‐the‐art material innovations, focusing on nanostructure‐dominated mixed ionic–electronic conduction. Subsequently, we elaborate on tailored microscale channel architectures, encompassing 1D fibers, 2D micro/nanoporous films, and 3D soft hydrogel networks to address both electronic and mechanical challenges. Furthermore, we highlight advances in scalable fabrication techniques such as printing/photolithography‐based approaches and vertical architectures for developing high‐density flexible OECT arrays. In addition, diverse bioelectronic applications are summarized, including biosensing, signal processing, implantable biointerfaces, and brain‐inspired computing, demonstrating the versatility of OECTs. The discussion concludes by outlining future directions to enhance device reliability and scalability, addressing critical challenges such as material stability and integration complexity. Through this comprehensive analysis, we provide a roadmap for advancing OECT micro/nanotechnology, inspiring future research and accelerating its adoption in bioelectronics.