Deterministic Lateral Displacement of Semiflexible Chain Dynamics in Microfluidic Pillar Arrays

Deterministic lateral displacement (DLD) is a high resolution size-based separation technique showing great potential for particle separation, especially for biological particle sorting. Over the past decade, rigid spherical particle separation using DLD method has been widely explored to facilitate the design of new DLD devices, while particles with different shapes and deformability have not been fully studied. Here, we investigate the migration dynamics of semi-flexible chains with high aspect ratio in gravity-driven DLD devices. Specifically, DNA linked semi-flexible colloidal chains serve as model high aspect ratio deformable particles and transport through a microfluidic pillar array device induced by a gravitational body force. Chain trajectories are presented using both experiments and simulation results. Similar to rigid spherical particles in the pillar arrays, zigzag and laterally displaced trajectories are observed for the longer and more flexible chains. In addition, the high aspect ratio and deformable nature of the chains lead to a richer local dynamical behavior, including bouncing, hairpin shape bending, sliding and hooking. We discuss how the deformability and size of chains affect their migration trajectories through microfluidic posts.