Organic Electrochemical Transistors for In Vivo Bioelectronics

• Published in: Advanced materials (Weinheim) 2021-12, Vol.33 (49), p.e2101874-n/a
• Main Authors: Nawaz, Ali, Liu, Qian, Leong, Wei Lin, Fairfull‐Smith, Kathryn E., Sonar, Prashant
• Format: Article
• Language: English
• Subjects: Bioelectricity; electrophysiology; in vivo bioelectronics; Interface stability; neural interfacing; Neurotransmitters; OECTs; organic transistors; plant interfacing; Semiconductor devices; Transistors
• ISSN: 0935-9648; 1521-4095
• DOI: 10.1002/adma.202101874

Organic electrochemical transistors (OECTs) are presently a focus of intense research and hold great potential in expanding the horizons of the bioelectronics industry. The notable characteristics of OECTs, including their electrolyte‐gating, which offers intimate interfacing with biological environments, and aqueous stability, make them particularly suitable to be operated within a living organism (in vivo). Unlike the existing in vivo bioelectronic devices, mostly based on rigid metal electrodes, OECTs form a soft mechanical contact with the biological milieu and ensure a high signal‐to‐noise ratio because of their powerful amplification capability. Such features make OECTs particularly desirable for a wide range of in vivo applications, including electrophysiological recordings, neuron stimulation, and neurotransmitter detection, and regulation of plant processes in vivo. In this review, a systematic compilation of the in vivo applications is presented that are addressed by the OECT technology. First, the operating mechanisms, and the device design and materials design principles of OECTs are examined, and then multiple examples are provided from the literature while identifying the unique device properties that enable the application progress. Finally, one critically looks at the future of the OECT technology for in vivo bioelectronic applications. The role of organic electrochemical transistors in different in vivo bioelectronic applications, ranging from human electrophysiology to plant interfacing, is discussed. Particular emphasis is given on analyzing the key materials design and device design aspects that make these devices ideal for addressing future in vivo biological systems. Finally, some challenges, limitations, and future applications are critically assessed.