Comparative Sensibility Study of WO₃ ph Sensor Using EGFET and Ciclic Voltammetry

In this present study, the investigation about pH sensorial properties of WO₃, via sol-gel, was evaluated by Voltammetry and Extended Gate Field Effect Transistor techniques. The X-ray diffractogram indicates the presence of a lamellar structure, d = 0.69 nm, resulting in WO₃.2H₂O. From Scanning Electron Microscopy of WO₃.2H₂O was observed a process corresponding to the delamination which consists of irregular stacking with rounded platelets. The WO₃.2H₂O was investigated as a pH sensor in the pH range 2–12, by the EGFET and Voltametry techniques presenting a sensitivity of 52 mV/pH and 60 mV/pH, respectively. These results can indicate that both Voltammetry and EGFET techniques present values close to the theoretical limit (59.2 mV/pH) as well as the material is a promising candidate for applications as a pH sensor and as disposable biosensor in the future.

tungsten oxide; pH sensor; voltammetry; EGFET