Organic electrochemical transistor-based theranostics: materials, mechanisms, and system integration

Abstract Organic electrochemical transistors (OECTs), leveraged by their unique volumetric doping mechanism and ultra-high transconductance performance, have emerged as a pivotal device platform for constructing high-performance bioelectronic interfaces. OECT-based theranostics aim to develop intelligent closed-loop systems that integrate sensing, decision-making, and execution, thereby overcoming the latency and discretization limitations of traditional medical models when managing dynamic physiological fluctuations. This article systematically reviews the performance evolution of OECT materials from p-type to n-type, discusses critical strategies for enhancing device stability and transconductance density, such as side-chain engineering and ladder-type molecular design, while emphasizing the essential role of complementary logic circuits in minimizing the static power consumption of implantable electronics. Furthermore, breakthroughs in OECT-based neuromorphic computing are addressed; by simulating synaptic plasticity (STP/LTP) and engineering organic electrochemical neurons (OECNs), a highly efficient sensing-computing closed-loop architecture has been realized. The current application landscape of OECTs in electrophysiological monitoring, neurochemical sensing, and multimodal synergistic sensing is detailed, alongside a summary of high-density array fabrication and system integration strategies, including 3D printing, inkjet printing, and 3D hydrogel integration. Finally, future outlooks are provided, focusing on challenges such as the environmental stability of n-type materials, multimodal signal crosstalk, and long-term clinical reliability.