Silicon-Based Glucose Oxidase Working Electrode for Glucose Sensing.

We created a glucose oxidase (GOx) working electrode on a silicon-on-insulator (SOI) wafer for glucose sensing. The SOI wafer was electrically connected to a copper wire, and the GOx was immobilized onto the hydrophilized SOI surface via silanization with aminopropyltriethoxysilane and glutaraldehyde. Electrochemical analysis (i.e., cyclic voltammetry) was employed to identify the sensing mechanism and to evaluate the performance of these SOI-GOx glucose sensors. The response of the SOI-GOx working electrode was significantly higher in the presence of oxygen than that without oxygen, indicating that a hydrogen peroxide pathway dominated in our SOI-GOx electrode. The height of cathodic peaks increased linearly with the increase of glucose concentrations up to 15 mM. The SOI-GOx working electrode displayed good stability after more than 30 cycles. On the 133 day after the electrode was made, although the response of the SOI-GOx electrode dropped to about one-half of its original response, it was still capable of distinguishing different glucose concentrations. This work suggests that the SOI-GOx working electrode that we developed might be a promising candidate for implantable glucose sensors.