Three-dimensional gravity-driven deterministic lateral displacement

TL;DR

This paper introduces a three-dimensional deterministic lateral displacement system that enhances particle separation by utilizing both in-plane and out-of-plane trajectories, allowing for more effective size-based fractionation.

Contribution

The study extends traditional 2D DLD systems into 3D by incorporating out-of-plane particle motion, supported by a theoretical model and experimental validation.

Findings

In-plane motion matches 2D DLD predictions

Out-of-plane displacement varies with particle size and orientation

Enables simultaneous multi-stream particle separation

Abstract

We present a simple solution to enhance the separation ability of deterministic lateral displacement (DLD) systems by expanding the two-dimensional nature of these devices and driving the particles into size-dependent, fully three-dimensional trajectories. Specifically, we drive the particles through an array of long cylindrical posts, such that they not only move in the plane perpendicular to the posts as in traditional two-dimensional DLD systems (in-plane motion), but also along the axial direction of the solid posts (out-of-plane motion). We show that the (projected) in-plane motion of the particles is completely analogous to that observed in 2D-DLD systems. In fact, a theoretical model originally developed for force-driven, two-dimensional DLD systems accurately describes the experimental results. More importantly, we analyze the particles out-of-plane motion and observe that, for certain orientations of the driving force, significant differences in the out-of-plane displacement depending on particle size. Therefore, taking advantage of both the in-plane and out-of-plane motion of the particles, it is possible to achieve the simultaneous fractionation of a polydisperse suspension into multiple streams.