Flexible AlN Coupled MOSFET Device for Touch Sensing

This work presents touch sensing device with flexible piezoelectric Aluminium Nitride (AlN) capacitor tightly coupled with a MOSFET device. Unlike conventional high temperature deposition, the AlN in this work was sputtered on polyimide at room temperature to obtain a flexible piezoelectric touch sensing element. Further, the proposed device has reliable operation as unlike other similar touch sensing devices, where high voltage needed to polarize the piezoelectric layer poses a major risk for the MOSFET operation, the AlN does not require any poling. The touch sensor has been evaluated in a force range of 0.5-3.5N and normalised change in drain current per unit force or the sensitivity is found to be 2.64 N-1.