Sensing Properties and Stability Analysis of Miniaturized Dual-Mode Uric Acid Biosensor Based on TiO₂ Extended Gate Field Effect Transistor

In this study, in order to control and obtain the uric acid concentration in blood more effectively and rapidly, a miniaturized dual-mode biosensor with rapid response, low cost and disposable has been developed, in this research, the major direction is to develop sensing devices with easy operation and detecting at home. The sensing devices are prepared by screen-printed technology which are based on extended gate field effect transistor (EGFET). The conductive material as electrical transmitted layer is printed on the flexible plastic substrate, and the TiO₂ sensing membrane is deposited by radio frequency (R.F.) sputtering system. The high chemical stability of TiO₂ sensing membrane maintains the sensing responsibility during electrochemical response in pH environment. The sensing windows are defined to circular shape with 1.5 mm diameter by printing UV glue. The structure of sensing device is UV glue/TiO₂/carbon/silver/PET-substrate. The properties of sensing devices are compared with different substrates and membrane materials, and combine the enzyme immobilization technology on biosensor that applied in uric acid detection, in this study, we discuss the stability and reproducibility of device in the range covered the normal uric acid concentration in human blood. The dual-mode circuit provides potentiometric and amperometric mode combined with the sensing devices and measurement system. In concentration detection, dual-mode circuit provides potentiometer sampling and amperometric sampling for users. Moreover, dual-mode circuit which is applied to synchronic measurement and components analysis for several samples, the development of multi-biosensors are the research purpose presently.