Online oxygen measurements inside a microreactor with modeling of transport phenomena

Abstract

Oxygen imaging using an epifluorescent microscope was performed inside a microfluidic chip by utilizing nanosensor particles stained with oxygen-sensitive luminescent dye. The oxidation reaction of β-d-glucose to hydrogen peroxide and δ-d-gluconolactone by molecular oxygen in the presence of glucose oxidase from Aspergillus niger inside microreactors with Y-shaped microchannels was followed with this measuring technique. This reaction is widely used in diagnostics and biotechnology. Dissolved oxygen concentrations were measured at various flow rates and microchannel dimensions. Additional batch experiments and microreactor experiments with a reaction-free set-up were conducted. Mathematical models, ranging from a full 3D description of transport phenomena, incorporating convection, diffusion and enzymatic reaction terms along with the parabolic velocity profile, to simplified less precise models were developed to simulate the concentration of dissolved oxygen inside the microchannels, to assess the required model complexity for achieving precise results and to depict the governing transport characteristics at the microscale.