Abstract

Micro spaces are the environments, which provide insight into the mechanism of the process, and the microfluidic device is an excellent tool to gain a deeper understanding of the underlying mechanisms and principles of chemical and biochemical processes. 

In this lecture, the verification and validation of mathematical models developed for homogeneous and non-homogeneous microfluidic systems will be discussed. The oxygen imaging using an epifluorescent microscope was performed inside a microfluidic chip by utilizing nanosensor particles stained with oxygen-sensitive luminescent dye. The enzyme catalysed oxidation reaction of b-D-glucose to hydrogen peroxide and d-D-gluconolactone inside Y-shaped microchannels was followed with this measuring technique. 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. In more complex non-homogeneous system, azobenzene concentration profiles in multiphase microflows inside microchannels were measured with optimized thermal lens microscope (TLM) technique. Again, a detailed description of the transport phenomena by means of mathematical modeling is presented and validated by on-line measurements.