Modeling Electrochemical Impedance Spectroscopy Using Time-Dependent Finite Element Method.

Area of Science:

• Electrochemistry
• Computational Modeling
• Sensor Technology

Background:

• Electrochemical Impedance Spectroscopy (EIS) is vital for characterizing electrochemical systems.
• Accurate modeling of interdigitated electrodes is essential for sensor development.
• Understanding ion transport and electrical properties is key to EIS interpretation.

Purpose of the Study:

• To develop a time-dependent finite element method (FEM) model for simulating a 2D interdigitated electrode.
• To investigate the influence of various physical phenomena on EIS measurements.
• To provide insights for optimizing EIS sensor design and performance.

Main Methods:

• Utilized the finite element method (FEM) in COMSOL Multiphysics for simulation.
• Incorporated ion transport (Nernst-Planck), electric field (Poisson), Stern layer effects, and sheet resistance.
• Validated the model by comparing simulation results with experimental data.

Main Results:

• The model successfully reproduced key features of experimental EIS measurements.
• Multiple excitation cycles are needed for stable impedance measurements.
• Low frequencies (<1 kHz) show significant Stern layer voltage drop; high frequencies (>100 kHz) are dominated by sheet resistance.
• Excitation voltage amplitude affects linearity, especially at low concentrations.

Conclusions:

• The developed FEM model offers quantitative insights into EIS sensor behavior.
• Identified critical factors for high-frequency and low-concentration measurements.
• The model serves as a foundation for future biosensing applications with functionalized electrodes.