Modeling Microfluidic Separations Using COMSOL Multiphysics

B.A. Finlayson[1], and R.A. Shaw[2]
[1]University of Washington, Seattle, WA, USA
[2]National Research Council of Canada, Winnipeg, MB, Canada
Published in 2010

Infrared spectroscopy can be used to identify chemicals in a stream provided the signal is strong enough. A microfluidic device is modeled here with the objective of separating serum components so as to enhance the metabolite/protein concentration ratio. Serum contains creatinine (a representative metabolite) and albumin (representative protein). The laminar fluid diffusion interface (LFDI) device brings the serum in contact with water, the creatinine diffuses rapidly into the water, while the albumin diffuse more slowly, and then aspirate a product containing significant creatinine but very little albumin.

The goal of the simulations is to predict the composition of the aspirated product using various two-dimensional models to see if the essential features are contained in them. In addition, an analytic solution is derived for the flow of two immiscible fluids between flat plates. Various fluid mechanical insights are found: converging flow at the inlet, separating flow at the exit, and the difference between 2D and 3D simulation results.