Investigating the impact of pillar shape on flexible erythrocyte separation through deterministic lateral displacement

The deterministic lateral displacement (DLD) method has gradually moved beyond the separation of spherical rigid particles and has been successfully applied to the field of biological cells, especially to the separation of disc-shaped flexible erythrocytes. Different shapes of micropillars in the DLD device significantly affect the sorting performance of erythrocytes. We investigated the effect of the flow field in the gap of micropillars of different shapes (circular, triangular, I-shaped) on the behavior of erythrocyte tumbling motion. The simulation results showed that in the I-shaped pillar DLD device, compared with the circular and triangular pillars, the erythrocytes exhibited a stable and continuous flipping motion during the movement along the array offset direction, which enabled the effective separation size to be maintained at a high level. In addition, the formula for calculating the critical diameter of the I-shaped pillar DLD array for separating erythrocytes was obtained by fitting, which provides strong support for a more efficient design of the I-shaped pillar DLD device dedicated to erythrocyte sorting.