Highly accurate deterministic lateral displacement device and its application to purification of fungal spores

Abstract

We have designed, built, and evaluated a microfluidic device that uses deterministic lateral displacement for size-based separation. The device achieves almost 100% purity and recovery in continuously sorting two, four, and six micrometer microspheres. We have applied this highly efficient device to the purification of fungal (Aspergillus) spores that are spherical ( approximately 4 mum diameter) with a narrow size distribution. Such separation directly from culture using unfiltered A. niger suspensions is difficult due to a high level of debris. The device produces a two to three increase in the ratio of spores to debris as measured by light scatter in a flow cytometer. The procedure is feasible at densities up to 4.4x10(6) sporesml. This is one of the first studies to apply microfluidic techniques to spore separations and has demonstrated that a passive separation system could significantly reduce the amount of debris in a suspension of fungal spores with virtually no loss of spore material.

Rotational separation of non-spherical bioparticles using I-shaped pillar arrays in a microfluidic device

“…Beads (2.5 mm) peaked at B16 ± 1.7% separation at channel 6, whereas the output distribution spread was wide and relatively evenly distributed along channels 4-15. The spread that is observed here seems counter-intuitive to the previous performance of DLD devices, which enables distinct separations 18,21,25 . The observed phenomenon could be due to DLD mixed separation mode and further elaborated in Supplementary Note S1 (refs 26-28).…”

“…This separation principle is based on DLD, which has been established as an efficient technique for the continuousflow separation of particles that are dependent on their spherical dimension, by using conventional cylindrical pillars [18][19][20][21] . Accounting for the shape of particles, we hypothesize that inducing rotations of non-spherical particles will increase the effective separation size of the particles.…”

Inertia and scaling in deterministic lateral displacement

“…[1][2][3][4][5][6][7][8][9][10] It has, in fact, been successfully used in a number of applications, especially for the separation of biological samples. [11][12][13][14][15][16][17][18] Although in most cases DLD is described (and investigated) as a size-based separation technique, it could also separate particles based on shape and flexibility 19,20 and may contribute to the growing field of chiral separation. 21,22 We have shown that a simple model 23,24 that describes the motion of a suspended sphere around an individual obstacle in the DLD array (which we refer to as a particle-obstacle collision) predicts the separation capability of the system.…”

Large-Volume Microfluidic Cell Sorting for Biomedical Applications

“…Davis and coworkers (37) reported fractionating blood components (platelets, RBCs, and WBCs) using the DLD technique. Inglis et al (38) have also applied DLD to purify fungal Aspergillus spores of about 4 μm with a density of up to 4.4 × 10 6 spores/ml. Their device successfully isolated 99% of the target particles while eliminating 96% of smaller and larger particles.…”