A Verilog-A-Based Redox-Signal Transduction Model for Co-Simulating Surface-Bound Electrochemical Biosensors and...

Area of Science:

• * Electrochemical biosensor modeling
• * Circuit simulation for biosensing applications

Background:

• * Surface-bound electrochemical aptamer-based (E-AB) sensors offer high selectivity and sensitivity for continuous biomolecular monitoring.
• * Accurate co-simulation of E-AB sensors with readout circuits is challenging due to complex electrode-electrolyte interface behavior and electron-transfer kinetics.

Purpose of the Study:

• * To develop a compact, SPICE-compatible electrochemical cell model for surface-bound E-AB sensors.
• * To improve the physical interpretability and numerical stability of circuit simulations for biosensors.

Main Methods:

• * Implemented a Verilog-A model combining Marcus-Hush electron-transfer kinetics with a fractional-order RC-ladder representation of the electrical double layer (EDL).
• * Validated the model using square-wave voltammetry (SWV) on two E-AB sensors across various frequencies and concentrations.
• * Co-simulated the model with a transimpedance amplifier to compare electronic noise spectra with experimental data.

Main Results:

• * The model accurately captured electron-transfer kinetics, thermodynamics, and concentration response (Langmuir isotherm).
• * Simulated transient currents aligned well with experimental data.
• * Co-simulation with a transimpedance amplifier yielded electronic noise spectra closely matching experimental results, outperforming the simplified Randles circuit model.

Conclusions:

• * The proposed model provides a physically grounded framework for simulating surface-bound redox-based electrochemical biosensors.
• * Enables accurate co-simulation of E-AB sensors with readout circuits, facilitating biosensor design and development.
• * Advances continuous in-vivo and in-vitro biomolecular monitoring capabilities.