Multiphysics Modeling of the Electrochemical Response of Screen-Printed Electrodes for Sensing Applications

In this work, we present and validate a new 3-D COMSOL Multiphysics model capable of simulating the cyclic voltammetry (CV) and the electrochemical impedance spectroscopy (EIS) response of screen-printed devices. The proposed model considers the dominant electrical and electrochemical phenomena on the electrodes and in the electrolyte solution with redox reactions occurring at the metal/solution interface. The terminals of the simulated device are virtually connected to an equivalent circuit of a potentiostat in order to apply the potential and perform the CV readings with possibility to extend to other types of voltametric measurements. The model is calibrated on screen-printed devices through dedicated sets of experimental measurements that use CV and EIS with 10 mM [Fe(CN)6]<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$^{{3}-/{4}-}$ </tex-math></inline-formula> as redox mediator in phosphate-buffered saline (PBS) solution. The model parameters for each device are retrieved from the experimental measurements, e.g., double layer capacitance, red/ox diffusivity, electrolyte conductivity equilibrium, and so on. After the calibration, the model is capable of simulating CV responses using different scan rates and redox couple concentrations. The obtained simulated CV signals are significantly consistent with the experimental data, fitting well the experimental curves of both the devices. The simulated/experimental peaks differ less than 50 mV, while the anodic and cathodic current peaks vary only of few microamperes (<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\lt 11~\mu $ </tex-math></inline-formula>A), with values within the standard deviation of measurement experimental measurements. Finally, the proposed model will allow the simulation of more complex electrode morphologies and electrochemical conditions as well, as the model parameters are retrieved experimentally through specific measurements.

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