DLD pillar shape design for efficient separation of spherical and non-spherical bioparticles

Abstract

Particle sorting methods in microfluidic platforms are gaining momentum for various biomedical applications. Bioparticles are found in different shapes and sizes. However, conventional separation techniques are mainly designed for separation of spherical particles. Thus, there is a need to develop new methods for effective separation of spherical and non-spherical bioparticles for various applications. Deterministic lateral displacement (DLD) microfluidic methods have become popular for high separation resolution, simplicity, and predictability. However, shape sorting in the DLD separation methods is not well researched. Recently, we explored this area and found that pillar shapes in DLD significantly affect bioparticle separation. In this work, we designed a group of different pillar shapes with protrusions and groove structures with the hypothesis that pillar protrusions will induce particle rotation while pillar grooves will confine the particle rotational movement in a directed path for effective separation in a DLD pillar array. Using combinations of protrusions and grooves, 3-dimensional spherical particles, 2-dimensional planar disc-shaped red blood cells and 1-dimensional rod-shaped bacteria were separated and two interesting phenomena were observed. Firstly, the arrangement of pillar protrusions and grooves induces inertial movements, enhancing the separation of spherical particles. Secondly, non-spherical particles experience dominant rotational movements due to the protrusions and grooves which help in changing their orientations. This gives an opportunity to perform efficient separation based on the desired orientation (the longest dimension of the particles) by restricting or containing their movement within a specific DLD path.

Inhibition of clot formation in deterministic lateral displacement arrays for processing large volumes of blood for rare cell capture

“…However, erythrocyte contamination of the product was significant with nearly 4.5% of the input erythrocytes appearing in the product. At the high Reynolds number used in these flows (Re ~ 10), it has recently been reported that erythrocytes, which have a discoid shape, behave in a DLD array as if they have a much larger size than they do at low Reynolds number, an effect not observed for circular posts [32]. Thus more are collected as “large cells” than would otherwise occur.…”

Improving diagnosis of pneumococcal disease by multiparameter testing and micro/nanotechnologies

“…A combination of grooves and protrusions in a microfluidic device could successfully separate, 3D spherical particles, red blood cells (2D planar shaped) and rod shaped bacteria. The bacteria investigated in this work were: E. coli (rod-shaped or bacillus), K. pneumoniae (rod shaped), S. epidermidis (spherical or coccus) and Pseudomonas aeruginosa (rod-like or coccobacillus) (55). The final example is the work of Kang et al (56) who presented a method to selectively detect bacteria directly from milliliters of diluted blood in one step.…”

Numerical Study of Pillar Shapes in Deterministic Lateral Displacement Microfluidic Arrays for Spherical Particle Separation

“…These DLD devices with shaped pillars are found to have smaller critical sizes than circular ones [26]. Ranjan et al [28] validated that protrusions and groove structures substantially affected separation efficiency. In other words, DLD geometric characteristics play an important role in spherical particle separation.…”

“…Although a variety of pillar shapes in DLD devices have been evaluated experimentally [28], it is yet a rule of thumb in designing and optimizing DLD microfluidic arrays for efficient separation of biological samples. The critical size is of vital importance in DLD.…”