Deterministic lateral displacement (DLD) in the high Reynolds number regime: high-throughput and dynamic separation characteristics

2018 ◽  
Vol 22 (6) ◽  
Author(s):  
Brian M. Dincau ◽  
Arian Aghilinejad ◽  
Taylor Hammersley ◽  
Xiaolin Chen ◽  
Jong-Hoon Kim
Author(s):  
Brian Dincau ◽  
Arian Aghilinejad ◽  
Jong-Hoon Kim ◽  
Xiaolin Chen

Deterministic lateral displacement (DLD) is a common name given to a class of continuous microfluidic separation devices that use a repeating array of pillars to selectively displace particles having a mean diameter greater than the critical diameter (Dc). This Dc is an emergent property influenced by pillar shape, size, and spacing, in addition to the suspending fluid and target particle properties. The majority of previous research in DLD applications has focused on the utilization of laminar flow in low Reynolds number (Re) regimes. While laminar flow exhibits uniform streamlines and predictable separation characteristics, this low-Re regime is dependent on relatively low fluid velocities, and may not hold true at higher processing speeds. Through numerical modeling and experimentation, we investigated high-Re flow characteristics and potential separation enhancements resulting from vortex generation within a DLD array. We used an analytical model and computational software to simulate DLD performance spanning a Re range of 1–100 at flow rates of 2–170 μL/s (0.15–10 mL/min). Each simulated DLD array configuration was composed of 60 μm cylindrical pillars with a 45 μm gap size. The experimental DLD device was fabricated using conventional soft lithography, and injected with 20 μm particles at varying flow rates to observe particle trajectories. The simulated results predict a shift in Dc at Re > 50, while the experimental results indicate a breakdown of typical DLD operation at Re > 70.


Author(s):  
Kawkab Ahasan ◽  
Jong-Hoon Kim

Abstract Deterministic lateral displacement (DLD) is a method of inertial size-based particle separation with potential applications in high throughput sample processing, such as the fractionation of blood or the purification of target species like viral particles or circulating tumor cells. Recently, it has been shown that symmetric airfoils with neutral angle-of-attack (AoA) can be used for high-throughput design of DLD device, due to their mitigation of vortex effects and preservation of flow symmetry under high Reynolds number (Re) conditions. While high-Re operation with symmetric airfoils has been established, the effect of AoA for airfoil on the DLD performance has not been characterized. In this study, we present a high-Re investigation with symmetric airfoil-shaped pillars having positive and negative 15 degree AoA. Both positive and negative AoA configurations yield significant flow anisotropy at higher flow rates. The stronger shift of the critical diameter (Dc) was observed with negative AoA, but not in positive AoA device. The most likely contributor may be the growing anisotropy that develops in the AoA device at higher flow rates. This study shows that high-Re DLD design with airfoil shaped pillars requires significant consideration for pillar orientation to control flow symmetry.


Author(s):  
Arian Aghilinejad ◽  
Christopher Landry ◽  
George Cha ◽  
Xiaolin Chen

Abstract Cancer is among a major health concerns all over the world. Cancer metastasis, which defines as the migration of malignant cells from original sites to distant organs, is the main reason of death due to cancer and there is growing evidence that Circulating Tumor Cells (CTCs) are responsible for initiating the metastasis. Due to the importance of these bioparticles in biotechnology and medicine, there is a growing interest to study and separate them through different techniques especially microfluidic label-free technologies. One such technology, termed Deterministic Lateral Displacement (DLD) has recently shown promising abilities to separate cells and particles of different sizes. However, DLD is a separation method that takes advantages of the predictable flow laminae of low Reynolds number (Re) fluid flow. In order to achieve higher device throughput, effects of higher Reynolds number flow on DLD device should be studied. Additionally, the higher flow rates would apply higher forces and shear stresses on the cells which threaten the cell’s viability. In this study, employing numerical simulation, the effect of high Re number on DLD device for separating cancer cells has been investigated. Specifically, we conducted force analysis and by focusing on the downstream gap distance between the posts, we improved the device which results in less cell deformation. Our developed numerical model and presented results lay the groundwork for design and fabrication of high-throughput DLD microchips for enhanced separation of CTCs.


1994 ◽  
Vol 9 (3) ◽  
pp. 279-285 ◽  
Author(s):  
Rahima K. Mohammed ◽  
Tim A. Osswald ◽  
Timothy J. Spiegelhoff ◽  
Esther M. Sun

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