Fast and Long-Term Stable Nanofiber Channel Organic Electrochemical Transistor Sensor

Organic electrochemical transistor (OECT) has excellent transconductivity compared to field-effect transistor. It also has good operation compatibility in aqeuoust environemt including implanted bioconditions. In organic electrochemical transistor (OECT), the ion of electrolyte penetrates into the organic channel and changes the conductivity. Research using the OECT sensor for sensing bio electric signals and bio materials is being actively conducted. However, OECT has a slower response time and a shorter lifespan than conventional transistors.<br/>Here, we mixed PEDOT:PSS with polyacrylamide and electropin to produce nanofiber. This mixture have structural advantages over the existing film channel-type OECT by using nanofiber as a channel. First, it has a larger surface area in the same dimension than in the existing film type channel. The increase in the surface area leads to the increase in the penetration area of the ion, making it easier for the ion to penetrate. This allows for a faster response time(transient time) in terms of ion sensing. Second, it is stable in an underwater environment(in vitro) using polyacrylamide. It was confirmed that there was little change in performance even after 36 months in DI water. At room temperature in the phosphate buffer solution solution, the change in conductivity was maintained at around 10% even after 2 months. In addition, it was confirmed that there was little change in conductivity in an experiment in which 5000 cycles of repeated pulse signals were loadded. Third, PEDOT:PSS/polyacrylamide nanofiber is stretchable. Swelling and contraction occur in the process of dimethyl sulfoxide(DMSO) secondary doping in polyacrylamide. The crystallization of PEDOT:PSS occurs and its conductivity increases through DMSO secondary doping. In the case of PEDOT:PSS/polyacrylamide nanofiber, stretchability and conductivity are improved. In addition, there is no change in resistance to tensile stress, so it can be used as a stretchable sensor