Double layer capacitance measured by organic field effect transistor operated in water

Abstract

Pentacene ultra thin film transistors were exposed to water and operated with a conventional silicon/silicon oxide bottom gate and an electrolyte top gate controlled by a working electrode. The transistors are highly sensible (μV) to the electrochemical potential of the aqueous electrolyte. We show that dual gate operation permits the measurement of the double layer capacitance, C DL=14.6 μF/cm 2. The device exhibits a fast (4.6 ms) and stable response, without bias stress as opposed to conventional bottom gate operations, when controlled with the electrolyte gate. These features make the device a promising candidate for potentiometric transducers required for non-invasive electrophysiology. © 2012 American Institute of Physics.