| Summary: | 碩士 === 國立臺南大學 === 電機工程學系碩士班 === 101 === In this thesis, a voltammetry potentiostat with the function of wide range current measurement is proposed for the signal processing of electrochemical biosensors. The integrated voltammetry potentiostat can be combined with biosensors to develop a small size sensing device for human biological monitoring systems.
As far as the circuit design is concerned, at first, the range of biosensor current will be detected by a current detection circuit. Then, the biosensor current will be scaled to an appropriate current value (within 10mA) by a multi ratio current copier circuit. Next, the scaled sensor current will be converted into digital pulses by a sigma-delta modulator, where the frequency of digital pulses is proportional to the magnitude of biosensor current.
The proposed voltammetry potentiostat is designed and fabricated by TSMC 0.35贡m CMOS process. The specifications of the proposed potentiostat are described as follows: the power supply voltage is 3.3 V, the potential of working electrode is 1.2 V, the range of bio-potential of electrochemical biosensor is 0~1.2 V, the maximum range of the measured sensor current is 2.1 mA, the minimum current resolution is 1 nA, the signal processing dynamic range is 126 dB, and the chip layout area is 1.44 × 1.42 mm2. After the fabrication of the proposed chip, this chip has been tested in our laboratory and the measured results show that this chip’s functions can work well.
Finally, the proposed voltammetry potentiostat is integrated with microprocessor to construct the complete signal processing system of electrochemical biosensor, which is used to measure melatonin biosensor for verification. Experimental results show that the measured results of the proposed potentiostat has the same trend with the measured results of the commercial ones.
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