Current status and further development of deterministic lateral displacement for micro-particle separation

Abstract

Deterministic lateral displacement (DLD) is a passive, label-free, continuous-flow method for particle separation. Since its discovery in 2004, it has been widely used in medical tests to separate blood cells, bacteria, extracellular vesicles, DNA, and more. Despite the very simple idea of the DLD method, many details of its mechanism are not yet fully understood and studied. Known analytical equations for the critical diameter of separated particles include only the gap between the columns in the DLD array and the fraction of the column shift. The dependence of the critical diameter on the post diameter, channel height, and a number of other geometric parameters remains unexplored. The problems also include the effect of flow rate and particle concentration on the critical diameter and separation efficiency. At present, DLD devices are mainly developed through numerical simulation and experimental validation. However, it is necessary to find fundamental regularities that would help to improve the separation quantitatively and qualitatively. This review discusses the principle of particle separation, the physical aspects of flow formation, and hydrodynamic forces acting on particles in DLD microchannels. Various analytical models of a viscous flow in an array of cylindrical posts are described. Prospects for further research are outlined.