Semianalytical modeling of the mass transfer in microfluidic electrochemical chips

TL;DR

This paper develops a semi-analytical model for mass transfer in microfluidic electrochemical chips, incorporating diffusion, electrochemical reactions, and flow profiles, enabling improved measurement techniques at the electrode interface.

Contribution

It introduces a semi-analytical solution extending the Leveque approximation for mass transfer in microfluidic electrochemical systems, including transfer functions for practical measurements.

Findings

Derived transfer functions for reactant concentration and current density.

Extended Leveque approximation to include electrochemical reactions.

Applicable to heat transfer modeling in similar microfluidic systems.

Abstract

This paper reports a mass transfer model of a reactant flowing in a large aspect ratio microfluidic chip made of a channel with electrodes on the side walls. A semi-analytical solution to the two-dimensional Fickian diffusion of a reactant in a microchannel, including the electrochemical reaction at the electrode interface, and the velocity profile obtained from the Navier-Stokes equations in a fully developed laminar regime is found . The solution is written in the Laplace domain in terms of transfer functions. The proposed solution is an extension of the Leveque approximation describing the reactant diffusion from the electrode to the middle of the microfluidic channel. The main applications of this work are the use of the obtained transfer functions for the measurement of the Faradic current density or the chemical concentration at the electrode interface. The study can also be extended to the heat transfer in microfluidic electrochemical chips (temperature or heat flux measurements at the electrode interface).