A Combinatorial Approach to Novel Boundary Design in Deterministic Lateral Displacement

Abstract: Deterministic lateral displacement (DLD) is a high-resolution separation technique used in various fields. A fundamental challenge in DLD is ensuring uniform flow characteristics across channel, particularly near sidewalls where pillar matrix inevitably loses its lateral periodicity. Despite attempts in the literature to improve boundary design, significant variations in critical diameter persist near sidewalls, adversely affecting the separation performance. We propose a combinatorial framework to develop an optimal design aimed at minimizing flow disturbances. We employ a set of parameterized boundary profiles, integrating multiple DLD channels, each with distinct design parameters, into a single microfluidic chip in parallel. Fluorescent beads are introduced into the chip via through-wafer via, flowing through inlet buses and DLD channels. The width of large-particle-laden stream downstream of channels is determined using fluorescence microscopy and image processing. The experimental results suggest an optimal range of design parameters for depletion and accumulation sidewalls. We conduct numerical simulations to further explore the experimental findings and refine the optimization. Comparison of results with existing design methodologies in the literature demonstrates the superior performance of the proposed framework. This work paves the way for design of DLD systems with enhanced performance, particularly for applications requiring high recovery rates and purity simultaneously.