A Novel Low Unity-Gain Frequency and Low Power Consumption Instrumentation Amplifier Design for RuO2 Uric Acid Biosensor Measurement

In this study, a novel low unity-gain frequency and low power consumption instrumentation amplifier (UGFPCIA) was designed and applied to the readout circuit of the potentiometric biosensor measurement system. The proposed UGFPCIA was developed using the Taiwan Semiconductor Manufacturing Company (TSMC) 0.18-mu m process technology, and simulated in a Laker analog design environment, and had a 1.5-V supply voltage for reduced power consumption. The uric acid (UA) biosensor based on RuO2 thin film was fabricated in this study. The sensing characteristics of the RuO2 UA biosensor were measured by the proposed UGFPCIA and the LT1167, a commercial instrumentation amplifier; then, their readout circuits were compared. According to the chip measurement results, the proposed UGFPCIA achieved a common-mode gain of -54 dB and a unity-gain frequency (UGF) of 588 kHz. Its power consumption was 397.92 mu W. Moreover, the measurement results showed that the sensitivity and linearity of the flexible arrayed RuO2 UA biosensor were 7.15 mV/(mg/dL) and 0.997, respectively. The LT1167 used a 2.3-V minimum supply voltage, while the proposed UGFPCIA used a 1.5-V minimum supply voltage; the power consumption is 84% lower than the former. This indicates that UGFPCIA was more stable during the measurement process and consumes lesser power.