AC and DC Differential Bridge Structure Suitable for Electrochemical Interfacial Capacitance Biosensing Applications

Area of Science:

• * Biosensing and electrochemical sensor technology.
• * Electronic instrumentation and circuit design.

Background:

• * Electrode-solution interfacial capacitance is a key parameter in biosensing.
• * Existing methods face challenges with sensitivity, interference, and drift.
• * Low-cost, high-performance biosensing platforms are in demand.

Purpose of the Study:

• * To present a novel capacitive differential bridge structure with AC/DC excitation and balancing.
• * To investigate the impact of component mismatch on bridge performance.
• * To provide design guidelines for balancing networks and readout circuitry.

Main Methods:

• * Development of a series RC balancing capacitive differential bridge.
• * Investigation of component mismatch effects on sensitivity and linearity.
• * Implementation of a custom real-time amplification/filtering readout board with sine fitting.
• * Utilization of Microcystin-(Leucine-Arginine) toxin dilutions for proof of concept.

Main Results:

• * The proposed bridge structure demonstrates higher sensitivity and reduced common-mode interference.
• * An 8-bit detection resolution was achieved for a 1% fractional capacitance change.
• * The system successfully detected minute capacitance changes at the electrode-solution interface.
• * Characterization and measurement results validate the effectiveness of the proposed structure.

Conclusions:

• * The developed capacitive differential bridge is effective for low-cost biosensing.
• * The series RC balancing structure enhances sensitivity and drift control.
• * The study provides a practical guideline for designing high-resolution capacitive biosensors.