The fluidic resistance of an array of obstacles and a method for improving boundaries in deterministic lateral displacement arrays

Abstract

Deterministic Lateral Displacement (DLD) is a microfluidic method of separating particles by size. DLD relies on precise flow patterns to deliver highresolution particle separation. These patterns determine which particles are displaced laterally, and which follow the flow direction. Prior research has demonstrated that the lateral array boundaries can be designed to improve the uniformity of the critical size and hence separation performance. A DLD device with an invariant critical size throughout is yet unknown. In this work we propose a 3D design approach. We first represent the flow through the DLD as a 2D lattice of resistors. This is used to determine the relative flow resistances at the boundaries that will deliver the correct flux patterns. We then use the Lattice Boltzmann Method to simulate fluid flow in a 3D unit cell of the DLD and measure the fluidic resistance for a range or typical dimensions. The results of this work are used to create a new equation for fluidic resistance as a function of post size, post height, and post spacing. We use this equation to determine array geometries that should have the appropriate resistances. We then design and simulate (in COMSOL) complete devices and measure fluid fluxes and first flow-lane widths along the boundaries. We find that the first flow-lane widths are much more uniform than in any devices described previously. This work provides the best method for designing periodic boundaries, and enables narrower, shorter and higher throughput DLD devices.

Deterministic Lateral Displacement: Challenges and Perspectives

“…A related problem is the design of the nonperiodic lateral device boundaries. Strategies for improving the flow patterns and particle dynamics near boundaries exist. − However, no approach has yet delivered perfect DLD boundaries in three dimensions (3D).…”

Using symmetry to control viscoelastic waves in pillar arrays

“…21 Furthermore, the geometry of the pillar array and device boundaries may introduce a lateral ow component, 22 an effect that can be somewhat mitigated by the addition of carefully designed compensatory structures to the array boundaries. 23,24 For DLD, decreasing the symmetry of the cross section of pillars from circular to triangular 21,25 has been used to decrease the critical size, the propensity for clogging and to increase the sensitivity to deformability when sorting cells. 26 In viscoelastic ows, longitudinal symmetry is broken by deadzones forming upstream of pillars.…”

A Review of Capillary Pressure Control Valves in Microfluidics

“…Microfluidic processes have strong potential in biomedical applications due to their small volume of samples and reagents, high throughput, and potential for automation. After decades of development, microfluidic devices have moved partly from the laboratory to practical applications, such as cell separation [3,4], analytical reactions and detections [5,6], immunoassays [7][8][9], as well as polymerase chain reaction (PCR) [10][11][12].…”