A cyclic voltammetry electrochemical sensing chip was implemented with a time-based readout circuit and a current feedback control loop for wide-range and high-linearity current detection. The design utilizes a chopper-stabilized, low-noise potentiostat circuit and a delay chain time-to-digital converter to improve accuracy and the conversion rate. A current feedback loop is employed to mitigate nonlinearity of the current-to-frequency converter. Also, an on-chip pattern generator with a current reducer is used to create area-efficient, multi-rate ramp signals for cyclic voltammetry and fast-scan cyclic voltammetry measurements. The chip is fabricated using a 0.18-μm CMOS process. It achieves an 8-nA current resolution in the current range of -7 A to 10 A with an R2 linearity of 0.999 while consuming 19 W. The Allan deviation floor is 4.83 Hz at the 7-second integration window, resulting in an 87-pArms input-referred current noise. The applicable limit of detection for K3[Fe(CN)6] concentration is 31 pM. To measure various reactions, the scan rate can be adjusted from 0.008 V/s to 400 V/s with a throughput data rate of up to 50 kS/s.
|Journal||IEEE Transactions on Biomedical Circuits and Systems|
|State||Accepted/In press - 2021|
- Current measurement
- Frequency conversion
- high data throughput
- on-chip pattern generator