TbYxOy Electrolyte-Insulator-Semiconductor Glucose Biosensor

Abstract

We report a glucose biosensor based on glucose oxidase (GOD) immobilized on TbYxOy sensing film deposited on the Si substrate through reactive cosputtering in this study. The structural properties of TbYxOy sensing films annealed at different temperatures (600, 700, 800, and 900 °C) were carried out using X-ray photoelectron spectroscopy and atomic force microscopy to obtain the optimal annealing condition. The TbYxOy electrolyte-insulator-semiconductor (EIS) sensor annealed at 900°C exhibited a higher sensitivity of 59.79 mV/pH, a lower drift rate of 0.26 mV/h, and a smaller hysteresis voltage of 1 mV in comparison with the other annealing temperatures. We attribute this behavior to the formation of a honeycomb-like structure and the reduction of lattice defects to improve the TbYxOy stoichiometry. Moreover, we compared two surface modification techniques with 3-aminopropyltriethoxysilane (APTES) and APTES+glutaraldehyde (GA) to immobilize the TbYxOy film surface and thus the enzymatic GOD was covalently bounded to the functionalized surface of a TbYxOy EIS sensor. The TbYxOy glucose biosensor prepared 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 very promising sensing membrane materials for general clinical examination of blood glucose.