Fig. 2: Wet electrical characteristics and pH sensing.

Transfer characteristics of the WSe2(top)/MoS2(bottom) ISFET at different pH values during a forward and b reverse sweep of the back gate voltage (VBG), c schematic of the pH sensing mechanism showing the formation of surface charge on oxide and electric double layer (EDL) in the electrolyte, and d simplified equivalent model showing signal transduction in a double-gated device.