A layout-dependent formula for the critical separation size of parallelogram-type deterministic lateral displacement arrays

JC Zhang and HL Liu and HX Tang and JL Zhang and ZM Zhang, PHYSICS OF FLUIDS, 35, 052007 (2023).

DOI: 10.1063/5.0149106

The accurate and general formulation of the critical separation size is crucial for the effective design and application of passive microfluidic devices. However, the current formulas for the deterministic lateral displacement (DLD) technique are inadequate in accounting for its structural complexity. To address this limitation, we conducted mesoscopic hydrodynamics simulations to assess the separation performance of various parallelogram-type circular post arrays. Based on the simulation results, we developed a new layout-dependent formula that takes into account key geometric parameters, such as the lateral gap size, row shift fraction, and aspect ratio of downstream and lateral post-post distances, to characterize the lateral gap dimension, periodicity, and asymmetry of DLD arrays, respectively. This formula demonstrated high accuracy over a wide design space, precisely predicting the critical separation sizes of many asymmetric DLD devices in experiments. Furthermore, it is worth noting that when the downstream gap size expands, the veering flow strengthens, which, in turn, results in an increase in the critical separation size. These findings shed light on the unique separation mechanism induced by array asymmetry and present a powerful design tool for maximizing the potential of asymmetric DLD devices.

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