Enzymatic glucose biosensor based on TbY_xO_y electrolyte-insulator-semiconductor

We report herein a glucose biosensor based on glucose oxidase (GOD) immobilized on TbY_xO_y sensing film grown by reactive cosputtering. The structural properties of TbY_xO_y sensing films annealed at different temperatures (600, 700, 800, and 900°C) were performed using X-ray photoelectron spectroscopy and atomic force microscopy to identify the optimal annealing condition. The TbY_xO_y electrolyte-insulator-semiconductor (EIS) sensor annealed at 900°C exhibited a higher sensitivity of 59.79 mV/pH, a lower hysteresis voltage of 1 mV, and a smaller drift rate of 0.26 mV/h than did those prepared at the other annealing temperatures. We attribute this behavior to the formation of a honeycomb-like structure and a decrease in the amount of lattice defects improving the stoichiometry of TbY_xO_y film. Furthermore, we compared two surface modification techniques with 3-aminopropyltriethoxysilane (APTES) and APTES+glutaraldehyde (GA) to functionalize the TbY_xO_y film surface and thus the enzymatic GOD was covalently immobilized on the modified surface of a TbY_xO_y EIS sensor. The TbY_xO_y glucose biosensor treated with APTES+GA has a high sensitivity (19.85 mV/mM) in solutions containing glucose at concentrations in the range 2.8 mM. This TbY_xO_y EIS biosensor is adequate for general clinical examination of blood glucose.