Multiphysics Modeling of Electrochemical Impedance Spectroscopy Responses of SAM-Modified Screen-Printed Electrodes

Area of Science:

• Electrochemistry
• Materials Science
• Computational Modeling

Background:

• Screen-printed electrodes (SPEs) are widely used in electrochemical sensing.
• Self-assembled monolayers (SAMs) of 11-Mercaptoundecanoic acid (MUA) are crucial for modifying electrode surfaces.
• Electrochemical Impedance Spectroscopy (EIS) is a powerful technique for characterizing electrode-surface interfaces.

Purpose of the Study:

• To develop and validate a multiphysics model for simulating EIS responses of MUA-modified SPEs.
• To investigate the effect of MUA concentration on the electrochemical behavior of SPEs.
• To compare simulation results with experimental data for model calibration and validation.

Main Methods:

• Utilized COMSOL Multiphysics® for designing a 3D multiphysics model incorporating electrochemical phenomena, ion/electron transport, and measurement setup.
• Performed experimental cyclic voltammetry and EIS measurements on gold SPEs using a [Fe(CN)6]3-/4- redox couple before and after MUA immobilization.
• Calibrated the model using experimental data and simulated EIS responses for MUA concentrations ranging from 1 µM to 100 µM.

Main Results:

• The multiphysics model accurately simulated the EIS responses of MUA-modified SPEs, showing good agreement with experimental data.
• Simulations effectively captured the variations in EIS parameters with changing MUA concentrations.
• Model-derived surface coverage estimates and charge transfer resistance variations closely matched experimental values (within 2% difference).

Conclusions:

• The developed multiphysics modeling approach provides a reliable tool for predicting the electrochemical behavior of MUA-modified SPEs.
• The model's accuracy in simulating EIS responses validates its utility for surface characterization and sensor development.
• This work demonstrates the successful integration of computational modeling and experimental electrochemistry for understanding interfacial phenomena.