Modeling Shear Stress in Microfluidic Channels for Cellular Applications

Microfluidics provides a promising platform for biomolecule capture. Recent work has shown the feasibility of microfluidic devices for biomedical applications such as cell capture, angiogenesis promotion, and stem cell culture. Most microfluidic cell devices use rectangular channels. A physiologically relevant concern in microfluidic cell work is the shear stress experienced by the cells in these applications. We model shear stress in microfluidic channels with different cross-sectional areas, including rectangular, tapered, and semi-circular. Fluid flow will be modeled using the physical characteristics of water, the primary solvent used in microfluidic applications. Shear stress is analyzed at the surface of the channel and above the area of the captured cells, up to half the channel depth in each scenario using a Newtonian hydrodynamic shear stress calculation. We determine the maximum fluid velocity possible within each channel without exceeding in vivo shear stresses. Coupled with physiological cell dimensions, we propose the best channel geometry for microfluidic cell applications. The results of this study aid in microfluidic device design for biomedical application. These results establish a foundation for microchannel design in the areas of cell culture, cell capture, and drug discovery and screening.