Asymmetric lattice-shaped microchannel structures for continuous size-dependent cell sorting

Here we describe a continuous particle/cell sorting system using asymmetrically patterned, lattice-shaped microchannel array structures. The microchannel is composed of two types of microchannels, which are placed in a lattice pattern at a right angle. There is a difference between the densities of these two types of microchannels, which generates the asymmetric flow distribution at every intersection. Large particles/cells are separated from the streamline, resulting in the continuous size-dependent cell sorting. We fabricated PDMS microfluidic devices, and successfully sorted micrometer-sized particles based on size with high separation accuracy. It was clearly shown that the separation size of particles/cells was dominated by the microchannel geometries including the densities of the microchannels and the slanted angles. As an application for cell sorting, we demonstrated the blood cell separation from a diluted blood sample. Erythrocytes and leucocytes were accurately separated and the ratio of recovered leucocytes was raised to ~80%. The presented scheme of particle/cell sorting would become a simple but versatile tool that is useful for general medical and biochemical experiments.