High-Sensitivity pH Sensor Based on Electrolyte-Gated In2O3 TFT

In this letter, a pH sensor was demonstrated based on In
₂
O
₃
-channel electrolyte-gated thin-film transistor (EGTFT). The pH sensitivity is as high as ~75 mV/pH under low operation voltage (<;1.2 V) in the range of pH 2.00 to pH 9.18, which is over the Nernst limit of 59 mV/pH. A new theory was developed to interpret the high pH sensitivity by considering the solution as a gate dielectric. The results suggest that the EGTFT could be a potential candidate for biochemical sensors.