A time-based VLSI potentiostat for ion current measurements

A time-based CMOS integrated potentiostatic control circuit has been designed and fabricated. The design maintains a constant bias potential between the reference and working electrodes for an amperometric chemical sensor. A technique of converting input currents into time for amperometric measureme...

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Bibliographic Details
Published in:IEEE sensors journal 2006-04, Vol.6 (2), p.239-247
Main Authors: Narula, H.S., Harris, J.G.
Format: Article
Language:English
Subjects:
Amplification
Chemical sensors
Circuit design
CMOS
Current measurement
Cyclic voltammogram
Dynamic range
Electric potential
Electrical measurements
electrochemical sensing
Electrodes
Energy consumption
Integrated circuit measurements
Nonlinearity
potentiostat
Power generation
Time measurement
time-based processing
Very large scale integration
Voltage
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Summary:A time-based CMOS integrated potentiostatic control circuit has been designed and fabricated. The design maintains a constant bias potential between the reference and working electrodes for an amperometric chemical sensor. A technique of converting input currents into time for amperometric measurements is proposed. This technique eliminates current amplifying circuitry, reduces matching problems, and increases dynamic range while saving on area and power consumption. Redox currents ranging from 1 pA to 200 nA can be measured with a maximum nonlinearity of /spl plusmn/0.1% over this range. The design can be used to generate cyclic voltammograms for an electrochemical reaction by sweeping the voltages across a range specified by the user. Analog inputs are processed and digital outputs are generated without requiring a power-hungry A/D converter. A prototype chip has been fabricated in the 0.5-/spl mu/m AMI CMOS process. Experimental results are reported showing the performance of the circuit as a chemical sensor.
ISSN:1530-437X
1558-1748
DOI:10.1109/JSEN.2006.870142