A pressure sensitive ionic gel FET for tactile sensing

Field-effect-transistor (FET) is combined with an ionic gel to realize a pressure sensitive ionic-gel field-effect-transistor (PSG-FET) of high sensitivity and low operational voltage. The ionic gels form a layer of charge accumulation in a nanometric scale called the electrical double layer (EDL) on each electrode upon voltage application and exhibit quite high capacitance. The source-drain current through the ZnO channel increases from the initial 44 nA (without pressure) to 783 mu A (with pressure, 7 kPa), yielding an ON/OFF contrast as large as 1.7 x 10(4), due to EDLs, which is interpreted as a pressure sensitivity of 2.2 x 10(3) kPa(-1). Judging from the drain current and the gate voltage properties, the threshold voltage is calculated to be 2.8V owing the large capacitance created by the ionic gel. Published by AIP Publishing.