Hydrodynamic sorting of microparticles by size in ridged microchannels

Sorting and separation are key elements in many microfluidic processes. Here, we use computational modeling to design a hydrodynamic method for high-throughput separation of solid microparticles by size in microchannels. The rapid and high-resolution separation occurs due to a combination of two hydrodynamic effects: cross-stream inertial migration of particles and circulatory fluid flows created by periodic diagonal ridges protruding from opposite channel walls. This new continuous separation method operates in a wide range of Reynolds numbers, is insensitive to the magnitude of channel flow rate, and features simple design that can be readily integrated into microfluidic devices for massive sample analysis.