The Rising of Flexible Organic Electrochemical Transistors in Sensors and Intelligent Circuits

Flexible electronic devices in biomedicine, environmental monitoring, and brain-like computing have garnered significant attention. Among these, organic electrochemical transistors (OECTs) have been spotlighted in flexible sensors and neuromorphic circuits for their low power consumption, high signal amplification, excellent biocompatibility, chemical stability, stretchability, and flexibility. However, OECTs will also face some challenges on the way to commercialized applications, including the need for improved long-term stability, enhanced performance of N-type materials, integration with existing technologies, and cost-effective manufacturing processes. This review presents the device physics of OECTs in detail, including the evaluation of their various properties and the introduction of different configurations of the aforementioned OECTs. Subsequently, the components of this device and their roles are explained in depth, and the main ways to design and fabricate flexible OECTs are summarized. Following this, we summarize and analyze the principles and applications of OECTs for electrophysiological signal sensing, chemical sensing, biosensing, and sensor arrays. In addition, the concepts of OECT-based digital and neuromorphic circuits and their applications are presented. Finally, the paper summarizes the opportunities and challenges of OECT-based flexible electronics.