Development of extended gate field effect transistor (EGFET) biosensors based on mixed vanadium and titanium oxides for pH determination

Abstract

Biosensors are indispensable tools in the medical area because of their several applications. Each application requires a specific sensor. Biological flows are made of a great diversity of matter, that must be explored, and that leads to the development of new kinds of biosensors bringing significant advances in relation to selectivity, the simpleness of operation, reduction of the detection limit, analysis in real-time, reproducibility, etc. The ISFET (Ion Sensitive Field Effect Transistor) was the first semiconductor-based low-dimension chemical sensor. In comparison to other kinds of biosensors, it presents well-known advantages as miniaturization, high sensibility, low cost, and multi-detection. An alternative to building an ISFET is the so called EGFET (Extended Gate Field Effect Transistor). The EGFET, working as a pH sensor, contains a membrane deposited on a substrate. This membrane is responsible for the detection of ions and it is connected to a commercial MOSFET. For its use as a biosensor, the surface of the membrane of the EGFET is modified with the addition of enzymes. However, for a perfect immobilization of these enzymes, a material that possesses a surface that permits the entrapment of those specimens is necessary. Thus, the possibility of the use of oxides, as an example, vanadium or titanium oxides, might be very attractive due to their capacity of enzymes immobilization. Therefore, in this project the use of mixed titanium and vanadium oxide will be explored as a tool for the development of new materials and new morphological conceptions, aiming for their final application as a biosensor. Tests will be performed as a function of pH. (AU)