Simulation based optimization of microfluidic devices used for molecular enrichment

Microfluidic devices are used in several engineering fields ranging from biomedical to chemical to engineering for applications such as micro reactor, target molecular enriching and cell capturing. With regard to related applications, microfluidic devices offer advantages such as high surface area to volume ratio, increased mass transfer coefficient and portability in addition to their requirement of low analytes. Affinity based microfluidic devices with microscale posts have high compactness and mass transfer coefficient. In order to maximize the benefits offered by employing microfluidic devices, it is important to apply parametric study in the device designing work. This study is aimed at studying the operating and geometric parameters of microfluidic devices with square/rectangular microscale posts. The geometric parameters, such as aspect ratio of the microposts used, could possibly decide the performance of the device. Operating parameters studied are Reynolds number, Peclet number, Damköhler number, and equilibrium reaction constant. These parameters encompass the influence of velocity, diffusivity, density, viscosity, hydraulic diameter, inlet concentration of species and absorption/desorption reaction constants. This work theoretically analyzes the influence of the above mentioned parameters using COMSOL Multiphysics 4.2.a. The governing equations of microfluidic devices, i.e. Navier-Stokes equations and the advection-diffusion equation, subjected to the above mentioned operating parameters, are solved to obtain the velocity profile, pressure drop and concentration profile of the species. The metric used for analyzing the influence of each operating parameter is the capture efficiency, i.e. the ratio of outlet concentration to inlet concentration as well the pressure drop. The results of this study would improve the design of microfluidic devices used for chemical reactions as well as that used for protein enrichment.