An Extended-Gate Field-Effect Transistor Applied to Resistive Divider Integrated With the Readout Circuit Using 180nm CMOS Process for Uric Acid Detection

In this work, an extended-gate field-effect transistor (EGFET) applied to resistive divider integrated with the low unity-gain frequency and power consumption instrumentation amplifier (UGFPCIA) was developed successfully in a chip by the Taiwan Semiconductor Manufacturing Company (TSMC) 180nm CMOS process technology. The EGFET was designed based on the uricase/ruthenium dioxide (RuO2) sensing film to detect uric acid. The EGFET resistive divider achieved an effective measurement system due to its simplicity, convenience, and low cost. The current properties of EGFET based on the uricase/ RuO2 sensing film were also investigated using a semiconductor parameter analyzer. The uric acid concentration which covered the human body (2mg/dL to 7mg/dL) was applied in the measurement. The experimental results indicated that the EGFET resistive divider had a good uric acid sensitivity of 12.69 mV/(mg/dL), high linearity of 0.997, a fast response time of 8 seconds, hysteresis effect of 1.34 mV, LOD of 0.082 mg/dL, and good selectivity to uric acid.