Fundamentals and Applications of Organic Electrochemical Transistors for Biosensing

Abstract

Sensors that interface with biological environments such as human sweat, foods, and biofuels have garnered significant interest in recent years. The primary need in these complex fields is for a sensor device that can provide a real-time data stream in chemically unforgiving environments while also being portable or wearable and consume low power. Electronic devices that include organic semiconductors can begin to address these issues, as they are flexible, biocompatible and scalable materials. Yet, organic semiconductors are still being actively understood. They have relatively complex microstructural transformations when a voltage is applied to them in an electrochemical environment. Further, their unique ability to conduct both electronic charges and ions offer competing design principles when using them in a device. Understanding these processes occurring during device use is crucial for their application. This work first utilizes a model organic semiconductor, poly(3-hexylthiophene), to examine the microstructural changes occurring during electrochemical oxidation, and possible alternatives to improve ion conduction. Then, P3HT is used as the semiconductor channel in a floating gate organic electrochemical transistor modified with an ion gel to prevent degradation. The final device with modifications to each interface is used for sensing of a yeast used in the biofuel process, Yarrowia lipolytica. The critical interfacial factors that contribute to the overall performance of this device are examined, with a particular focus on reproducibility and manufacturability. It’s found that the final device can provide simplicity and amplification above traditional impedance-based sensors.