A Voltage-Assist 16-Channel Electrochemical Biosensor With Linearity Compensation

Area of Science:

• Electrochemical sensor technology
• Biomedical signal processing
• Low-power integrated circuit design

Background:

• Electrode capacitive loading causes significant error currents and settling issues in electrochemical signal acquisition.
• Existing methods struggle to accurately capture and compensate for these nonlinearities, impacting overall measurement reliability.

Purpose of the Study:

• To develop an efficient current-and-voltage dual-mode acquisition technique to mitigate inaccuracies caused by electrode capacitive loading.
• To reduce the complexity and power consumption of electrochemical signal acquisition systems.

Main Methods:

• A voltage front-end (VFE) was employed to acquire and compensate for electrode voltage errors and nonlinearities.
• An inverter-based capacitive trans-impedance amplifier (IB-CTIA) was utilized to enhance input transconductance for low-noise performance.
• The technique was verified using Interleukin-6 (IL-6) immunoassays on a prototype chip fabricated in a 180-nm CMOS process.

Main Results:

• The IB-CTIA achieved low input-referred current noise (3.9 pA_rms) and a high dynamic range (126 dB) with low static power consumption (18 μW).
• Nonlinear error compensation improved the correlation coefficient of IL-6 detection results from 0.951 to 0.980.
• The limit of detection (LoD) for IL-6 was reduced from 8.31 pg/mL to 6.90 pg/mL.

Conclusions:

• The proposed current-and-voltage dual-mode acquisition technique effectively compensates for electrode capacitive loading errors in electrochemical measurements.
• This approach enhances detection accuracy and sensitivity, making it suitable for low-power, high-performance biosensing applications.
• The relaxed gain and bandwidth requirements for the current front end simplify circuit design and reduce power consumption.