Highly sensitive palladium oxide thin film extended gate FETs as pH sensor

Abstract

It is well-known that palladium readily absorbs hydrogen gas at room temperature. Based on this unique property of palladium, palladium oxide (PdO)-sensitive membrane in the extended gate field-effect transistor (EGFET) configurations have been evaluated as a detector for hydrogen ions in pH buffer solutions. The PdO thin film was prepared by a two-step process through reactive electron beam evaporation and subsequent thermal oxidation in an optimal O2 flow. Our results indicate that the PdO-based EGFET sensor showed super-Nernstian sensitivity approximately 62.87mV/pH, while exhibiting good linearity as well as good stability between pH 2 and pH 12. Our research demonstrates that PdO membrane can be used in EGFET structure without compromising sensitivity achieved by conventional methods. Furthermore, the disposable PdO sensor shows great potential for low cost biochemical detection due to its simplified fabrication and measurement system.