Enhanced particle filtration in straight microchannels using shear-modulated inertial migration

In this work, we introduce a novel method for enhanced particle filtration using shear-modulated inertial migration in straight microchannels. Depending on their size, inertial lift causes particles to migrate toward microchannel walls. Using microchannels with high aspect ratio cross sections, the fluidic shear can be modulated, resulting in preferential equilibration of particles along the longer microchannel walls. Due to large lift forces generated in these high aspect ratio channels, complete particle filtration can be achieved in short distances even at low flow rates (Re < 50). Based on this principle, we use a straight microfluidic channel with a rectangular cross section to passively and continuously filter 1.9 mu m polystyrene particles. Overall, the proposed technique is versatile and can be easily integrated with on-chip microfluidic systems for filtration of a wide range of particle sizes, from micro- to nanoparticles. (C) 2008 American Institute of Physics. [DOI: 10.1063/1.2998844]