Development of biosensor for glucose estimation by ion sensitive field effect technique

In order to provide a better understanding of ion sensitive field effect device (ISFED) as a biosensor, the C-V characteristics and change in the flatband voltage of an electrolyte-insulator-semiconductor (electrolyte-SiO₂-Si) in response to different pH are examined. The response of silicon oxynitride as an insulator in the EIS to the pH is also examined and it shows good response compared to that of SiO₂. To test the feasibility of the application of C-V characteristics or EIS as a biosensor for glucose estimations, glucose oxidase as an enzyme is immobilized on the surface of EIS. The change in the capacitance of this system (biased at constant voltage) to different concentration of glucose is measured. The output response of differential capacitance shows a linear response to the variation of glucose concentration, thus providing a technique which after further modification could be used as a biosensor