Deterministic Lateral Displacement Microfluidic Chip for Minicell Purification

Abstract

Deterministic lateral displacement (DLD) is a well-known microfluidic technique for particle separation with high potential for integration into bioreactors for therapeutic applications. Separation is based on the interaction of suspended particles in a liquid flowing through an array of microposts under low Reynolds conditions. This technique has been used previously to separate living cells of different sizes but similar shapes. Here, we present a DLD microchip to separate rod-shaped bacterial cells up to 10 µm from submicron spherical minicells. We designed two microchips with 50 and 25 µm cylindrical posts and spacing of 15 and 2.5 µm, respectively. Soft lithography was used to fabricate polydimethylsiloxane (PDMS) chips, which were assessed at different flow rates for their separation potential. The results showed negligible shear effect on the separation efficiency for both designs. However, the higher flow rates resulted in faster separation. We optimized the geometrical parameters including the shape, size, angle and critical radii of the posts and the width and depth of the channel as well as the number of arrays to achieve separation efficiency as high as 75.5% on a single-stage separation. These results pave the way for high-throughput separation and purification modules with the potential of direct integration into bioreactors.

Fabrication of Embedded Microfluidic Chips with Single Micron Resolution Using Two‐Photon Lithography

“…DLD is a useful tool for the continuous separation of micrometer-sized particles such as bacteria, parasites, and tumor cells in the blood. [46,47] In general, this process utilizes laminar flow through a periodic array of obstacles (e.g., pillars) in a microfluidic device (see Figure 4), where the total fluid flux between each gap of the obstacles is divided into multiple streamlines. [46] Each streamline contains an equal fluid flux.…”

“…[46,49] Recently, our groups reported the separation of cells with rodlike and spherical morphologies with high efficiency of 75.5% by inserting a mixed solution containing both cell types into a DLD chip and using a flow rate of 50 μL min −1 . [47] Within the present work, we manufactured DLD chips with a row shift angle of 1°a nd a D c of 800 nm and 1.4 μm, respectively. Using Equation (S4) (Supporting Information) we calculated a pillar spacing G of 4 μm for a D c of 800 nm and of 7 μm for a D c of 1.4 μm.…”

Portable platform for leukocyte extraction from blood using sheath-free microfluidic DLD

“…25 Most importantly, they can separate cells without the need for sample pretreatment, such as labeling or lysis. 26 These advantages have made DLD a widely used method for separating and enriching samples containing various cell types and biological particles, including stem cells, 27 circulating tumor cells (CTCs), 28,29 blood cells, 30,31 bacteria, 32 bacterial minicells, 33 parasites, 34 spores, 35 and nano-sized particles. 36 Despite these benefits, several limitations of DLD devices have been identified such as low-throughput (ranging from 1 nL min −1 to 10 μL min −1 ), 22 occlusion in the regions around the posts, suboptimal purity of cell recovery (<70%), 25 and the requirement for hydrodynamic sample focusing using a sheath flow (see Table S1…”

Pumpless deterministic lateral displacement separation using a paper capillary wick

“…[31][32][33][34][35][36] Deterministic lateral displacement (DLD) is a well-known passive hydrodynamic separation method that relies on an array of micropillars to alter the path of particles based on their size and deformability. 37 Nearly all prior DLD works have used syringe pumps [38][39][40][41][42][44][45][46][47] or pressure regulators 43,[48][49][50][51][52][53][54][55][56][57][58][59] which increase the cost of using DLD and reduce the likelihood of its use in resource-limited situations. Few studies have accomplished a passive fluid driving method, 60,62,63 but in each of these cases, the separated products flow directly into the pump with no opportunity for direct product collection, though Tran et al 61 showed that cells drawn into the paper wick can be eluted after separation and are still viable.…”