We report herein a glucose biosensor based on glucose oxidase (GOD) immobilized on TbYxOy sensing film grown by reactive cosputtering. The structural properties of TbYxOy sensing films annealed at different temperatures (600, 700, 800, and 900 degrees C) were performed using X-ray photoelectron spectroscopy and atomic force microscopy to identify the optimal annealing condition. The TbYxOy electrolyte-insulator-semiconductor (EIS) sensor annealed at 900 degrees 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 TbYxOy film. Furthermore, we compared two surface modification techniques with 3-aminopropyltriethoxysilane (APTES) and APTES+glutaraldehyde (GA) to functionalize the TbYxOy film surface and thus the enzymatic GOD was covalently immobilized on the modified surface of a TbYxOy EIS sensor. The TbYxOy 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 TbYxOy EIS biosensor is adequate for general clinical examination of blood glucose. (C) 2016 The Electrochemical Society. All rights reserved.