Multiphysics Model for Simulation of Electrochemical Signals for Biosensing Applications

In this work, we present an optimized multiphysics model for simulating the electrochemical response of biosensors characterized by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The model is designed through COMSOL Multiphysics®, based on the 3D structure of screen-printed electrodes. The main electrochemical mechanisms, such as the metal/solution interface, the electron and ion currents, the potentials, and the measurement set-up, are implemented by the combination of several physics to achieve a complete and flexible model usable for different electrodes. Non-ideal capacitive contributions of the double layer are modeled through a newly implemented frequency-dependent equation. The model is calibrated by a dedicated set of experimental CV and EIS measurements on the devices under test with 10 mM [Fe(CN)6]3-/4- redox couple in phosphate-buffered saline. Then, we verify that the calibrated model is capable of predicting experimental EIS responses at different redox couple concentrations, as well as with different VDC and measurement parameters with the capability of changing the layout of the electrodes. The simulated signals are in good agreement with the experimental results in the entire range of analyzed frequencies with values well within the experimental error.