Super-Nernstian response of pH detection using metallic tungsten sensing electrode and extended-gate field effect transistor

EGFET pH sensor based on metallic W sensing electrode with stable and superior performance (65.86 mV/pH, r 2 =0.9972) has been demonstrated. The enhanced proton-exchange process and/or the number of H+ ions amplified by transferred electrons related to the hydrolyzation of W could be responsible for the super-Nernstian response of the proposed pH sensors. Firm understanding of the interfacial electronic reactions would be necessary for further development of W-based pH sensors.