Focusing and Sorting of Particles in Spiral Microfluidic Channels

We present a microfluidic device for focusing and separation applications of large particles exploiting inertial migration in curved microchannels. Due to the curvilinear geometry of the microchannel particles experience a combination of inertial lift and Dean drag forces causing a lateral equilibration at a position near the inner wall. Depending on the ratio of lift and Dean drag forces particles with different sizes occupy distinct equilibrium positions resulting in individual particle streams. For testing the principle, a 5 loop spiral microchannel was used. Channel width and spacing between successive loops were fixed to 500 mu m and the height to 220 mu m. To evaluate the device for sorting large insect cells, particle focusing and separation was carried out using fluorescently labeled 40 mu m and 60 mu m polystyrene beads. (C) 2011 Published by Elsevier Ltd.