Deterministic Lateral Displacement System with Inclined Elliptical Obstacles for Efficient Size-Based Separation of Microparticles

A deterministic lateral displacement system with inclined elliptical posts is demonstrated to sort spherical micrometer-sized solid particles. Numerical simulations via the finite-element method are performed to investigate the microfluidic system performance. Soft microparticles undergo deformations in designs with cylindrical posts or posts with sharp corners. Such deformations occur due to particle clogging between obstacles, which can disrupt the flow lanes. The proposed approach aims to eliminate these challenges. The calculations reveal a much-reduced rate of change in flow velocity between vertically inclined elliptical posts, compared to circular posts. The calculated critical particle sizes are more likely to follow the equation associated with the first flow lane width derived from a parabolic velocity profile at high fluid inlet rates, rather than the two semi-analytical models proposed for circular posts. The experimental and theoretical critical diameter data exhibited greater agreement with the critical diameter equation obtained using the curve-fitting method at lower fluid inlet rates. Overall, the minimum particle size decreased as the rate of flow increased. When assessing the connection between the two, a smaller critical diameter is achieved by decreasing the inclination angle. The adjustability of the system by rotating the posts is a major advantage of the proposed approach.