Potentiodynamic sensing with Organic Electrochemical Transistors

In recent years, bioelectronic interfaces have showed potential to successfully address some challenging applications of bioelectrochemistry. In particular, Organic Electrochemical Transistors (OECTs) based sensors and devices capable of on-site amplification and transduction of biochemical events have entered a variety of scientific fields, including wearable electronics, live cells monitoring and neural interfaces. Focusing on OECT-based sensors, conventional routes as well as more innovative strategies are exploited nowadays to functionalise the transistor elements and achieve the desired sensing performance. However, most of them rely on potentiostatic operation, where the poor control of electrochemical potentials due to the absence of a reference electrode intrinsically limits the achievement of a selective and reproducible response. Among all electrochemical methods, potentiodynamic techniques were applied to OECT sensing by our research group to overcome those issues and develop robust analytical tools towards quantitative, real-life applications. With this contribution, we present the main advantages offered by the potentiodynamic approach when OECT sensing is applied to the detection of redox-active molecules and ions. Upon optimization of the gate potential window and scan rate, poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) (PEDOT:PSS) based OECT sensors were successfully used to selectively detect dopamine in the presence of uric and ascorbic acid without any chemical or electrochemical functionalisation. Moreover, we have recently explored fat-soluble vitamins detection and proposed the first OECT sensor working in organic media. At the moment, the unique advantages of the OECT configuration are allowing us to investigate the potentiodynamic detection of a wound healing biomarker under flow conditions using a fully textile OECT.