Comparison of Carbon and Platinum Performance as TiO2 Membrane Substrate Material and Applied to Glucose Biosensor Using Amperometric Readout Circuit 

[[abstract]]This work proposes an amperometric glucose biosensor based on TiO2 enzyme-sensitive field effect transistor (EnFET). The sensing film of separated extended-gate field-effect transistor (SEGFET) was produced by screen-printed carbon fabricated on a flexible substrate and E-gun evaporating platinum. Titanium oxide (TiO2) was used with sol-gel technology or sputtering technology to deposit on the carbon or platinum substrate. Gel entrapment was adopted to fix glucose oxidase on TiO2 membrane to form enzyme membrane, which was made using enzyme immobilizing technology to establish EnFET The responding electric currents were measured using a three-electrode cyclic voltammetry (CV) measurement system. Experimental results exhibit that enzyme/TiO2/carbon and enzyme/TiO2/Pt show typical CV characteristics adopted three electrodes system. Platinum has large work function, so using it as the TiO2 conductive substrate owns close zero reaction potentials. Enzyme/TiO2/carbon shows one reaction peak clearly. Amperometric readout circuit including two operational amplifiers and a resistance was used of enzyme/TiO2/conductive-layer glucose sensors. The system used enzyme/TiO2 as working electrode, the counter electrodes (CE) and the reference electrode (RE) which are all TiO2/conductive-layer. In this experiment, the TiO2/conductive-layer is conductive, and so can be used as a counter electrode and a reference electrode to deliver the base potential for working electrode. The counter electrodes maintains for keeping a constant potential between RE and CE. The enzyme/TiO2/Pt results exhibit good linearity for glucose concentrations of between 0 and 400 mg/dL, and the corresponding sensitivity is approximately 74.1 (nV cm(-2)) (100 mg/dL)(-1) glucose.[[note]]SC