Pressure sensitive contact transistors operating in subthreshold regime

Abstract

Low power consumption and high sensitivity are essentially required for large-area flexible electronic sensor arrays. In this work we introduce organic thin-film transistors whose source-drain contact varies with applied pressure, called contact transistors. A carbon nanotube-coated micro-structure rubbery polymer is patterned to use as deformable source/drain electrodes of a bottom-gate and top-contact transistor. Both the contact resistance and contact area between the electrodes and a semiconductor layer vary upon pressure applied, leading to the change in transistor’s drain current. A high sensitivity of 10.69 kPa-1, a low limit-of-detection pressure of 12 Pa and a fast response time of ~ 140 ms are successfully realized with the pressure sensitive contact transistors operating in unprecedented subthreshold regime at low gate voltage (~ 1 volt) and ultralow power (~ 10 nW). We finally demonstrate a 5 x 5 active matrix pressure sensor array based on the contact transistors with pixel per inch of 12.83.