Microfluidic gating of an organic electrochemical transistor

A microfluidic-based organic electrochemical transistor is reported. The integrated microfluidic channel not only confines and directs the flow of liquid electrolyte over the active layer of the transistor but also provides the gate electrode for the transistor. The active layer employed in this work is poly(3, 4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS), which results in a transistor that is inherently "on" but that can be turned "off" through application of a positive gate voltage. The transistor behavior is understood in terms of an electrochemical mechanism and is shown to depend on the ionic strength of the electrolyte. The applicability of the device to microfluidic-based chemical and biological sensing is discussed.