(484h) Solvent-Resistant Electrochemical Transistors As Dual Sensing Platforms in Aqueous and Organic Media

Organic electrochemical transistors (OECTs) are promising contemporary sensing platforms for high-fidelity transduction of (bio)chemical signals into electrical observables. In an OECT, such signals cause can ions to inject from an electrolyte into an organic semiconducting polymer channel, changing its bulk conductivity and the output drain current. Such devices provide multiple advantages that make them apt for bioelectronics applications, namely (1) operating voltages less than 1 V, (2) direct interfacing with biologically relevant electrolytes for in vivo application, and (3) printable fabrication, for flexible and stretchable form factors. Despite such advantages, OECTs have only achieved high signal transduction with a narrow subset of channel materials, many of which require cytotoxic cross-linkers to prevent dissolution in aqueous environments and/or exhibit poor processability in carrier solvents. Consequently, there is a strong need to develop biocompatible channel materials with high-processability.

In this work, I discuss the development of single-component OECTs which are insoluble to both aqueous and organic media, yet can be facilely solution-processed from commercial water-soluble carboxylated polythiophene (CPTs) precursors post-synthesis. Such OECTs demonstrate robust stability and high pseudocapacitances even after repeated 2-V width voltage sweeps, as well as high transduction (transconductances = 30 mS at V_gate = -0.5 V) in aqueous and nonaqueous systems. Changes in doping state and ion injection will also be probed using spectroelectrochemistry and electrochemical quartz crystal microbalance to further understand the origin of high transconductance in these materials. In conjunction with other electrochemical techniques, we should be able to elucidate detailed characteristics that dictate high mixed ionic-electronic transport in these materials.