A Microfluidic Platform for Electrochemical Concentration and Detection
A poly(methyl methacrylate) (PMMA) microfluidic platform with a hot-embossed microchannel, 150 mm wide and 20 mm deep, was developed for multiple purpose detection using electrochemical methods. This device is able to accommodate a three-electrode system encased in 1/16" diameter PEEK tubing; and these electrodes are removable so they can be cleaned, polished and calibrated before and after experimental runs. Interchangeable micro-disc working electrodes can be used depending on the desired analyte detection; and a "leak-less" reference electrode was employed. Electrochemical characterization is performed using cyclic voltammetry and chronoamperometry at flow rates between 0.1 and 5 mL/min and analyte concentrations between 5 and 20 mM. The effect of scan rates between 20-100 mV/s during cyclic voltammetry was also studied. The application of convection greatly affects the current density at the electrode surface and the shape of the cyclic voltammograms. A 3D numerical simulation was developed for cyclic voltammetry and chronoamperometry in the device at different flows, concentrations, and scan rates, using COMSOL Multiphysics® software with the experimental and simulation results showing good agreement over the range of conditions studied and helped us identify several minor flaws in our platform design.