A computational and experimental study inside microfluidic systems: the role of shear stress and flow recirculation in cell docking

In this paper, microfluidic devices containing microwells that enabled cell docking were investigated. We theoretically assessed the effect of geometry on recirculation areas and wall shear stress patterns within microwells and studied the relationship between the computational predictions and experimental cell docking. We used microchannels with 150 mu m diameter microwells that had either 20 or 80 mu m thickness. Flow within 80 mu m deep microwells was subject to extensive recirculation areas and low shear stresses (< 0.5 mPa) near the well base; whilst these were only presented within a 10 mu m peripheral ring in 20 mu m thick microwells. We also experimentally demonstrated that cell docking was significantly higher (p < 0.01) in 80 mu m thick microwells as compared to 20 mu m thick microwells. Finally, a computational tool which correlated physical and geometrical parameters of microwells with their fluid dynamic environment was developed and was also experimentally confirmed.M.C. and M. M. were supported by the Progetto Roberto Rocca Collaboration. The Khademhosseini group is funded by the US Army Engineer Research and Development Center, the Institute for Soldier Nanotechnology, the National Science Foundation and the National Institute of Health grants (HL092836, EB009196 and DE019024). B.G. Chung was partially supported by the National Research Foundation of Korea (Grant Number R11-2008-044-01001-0) and Korea Industrial Technology Foundation (KOTEF) through the Human Resource Training Project for Strategic Technology. The authors thank Professor Marjo Yliperttulaa and Professor Edward Haeggstrom for helpful discussion