Breakdown of deterministic lateral displacement efficiency for non-dilute suspensions: A numerical study

Vernekar, Rohan; Krüger, Timm

doi:10.1016/j.medengphy.2015.06.004

Cited by 21 publications

(40 citation statements)

References 32 publications

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“…We have also performed simulations with dense RBC suspensions for various capillary numbers, viscosity contrasts and row-shift fractions. Our findings agree well with the numerical [57] and experimental [26] studies:…”

Section: Resultssupporting

confidence: 92%

“…So it is difficult to separate small rigid particles or stiff cells from dense suspensions because those would zig-zag, too. This result agrees with the numerical [57] and experimental [26] studies which use shallow devices (See Section 3.4).…”

Section: Contributionssupporting

confidence: 90%

“…Regarding numerical methods, all the studies above used either the immersed boundary method [34,50,57], lattice-Boltzmann method [34,57], fictitious domain method [60] or dissipative particle dynamics [22,62]. Here, we use our in-house algorithms based on the boundary integral equation formulation for Stokesian particulate flows [28].…”

Section: Related Workmentioning

confidence: 99%

“…This renders its systematic analysis infeasible even in 2D. In order to evade the computational cost the numerical studies conducted so far in this area reduced the simulation domain to a single pillar by assuming periodicity [34,50,57,60,62]. However, one pillar with periodic conditions requires imposing an artificial lateral force to enforce zero net lateral flow since in real DLD devices the lateral flow is restricted by the walls.…”

Section: Dld Modelmentioning

confidence: 99%

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Sorting same-size red blood cells in deep deterministic lateral displacement devices

Kabacaoglu

Biros

2018

J. Fluid Mech.

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Microfluidic sorting of deformable particles finds many applications, for example, medical devices for cells. Deterministic lateral displacement (DLD) is one of them. Particle sorting via DLD relies only on hydrodynamic forces. For rigid spherical particles, this separation is to a great extend understood and can be attributed to size differences: large particles displace in the lateral direction with respect to the flow while small particles travel in the flow direction with negligible lateral displacement. However, the separation of non-spherical deformable particles such as red blood cells (RBCs) is more complicated than rigid particles. For example, is it possible to separate deformable particles that have the same size but different mechanical properties?We study deformability-based sorting of same-size RBCs via DLD using an in-house integral equation solver for vesicle flows in two dimensions. Our goal is to quantitatively characterize the physical mechanisms that enable the cell separation. To this end, we systematically investigate the effects of the interior fluid viscosity and membrane elasticity of a cell on its behavior. In particular, we consider deep devices in which a cell can show rich dynamics such as taking a particular angular orientation depending on its mechanical property. We have found out that cells moving with a sufficiently high positive inclination angle with respect to the flow direction displace laterally while those with smaller angles travel with the flow streamlines. Thereby, deformability-based cell sorting is possible. The underlying mechanism here is cell migration due to the cell's positive inclination and the shear gradient. The higher the inclination is, the farther the cell can travel laterally. We also assess the efficiency of the technique for dense suspensions. It turns out that most of the cells in dense suspensions does not displace in the lateral direction no matter what their deformability is. As a result, separating cells using a DLD device becomes harder.• We investigate the cell dynamics in DLD flow, i.e., we study cell's inclination angle and lateral velocity in Sections 3.1 and 3.2.• We compare these cell-in-DLD dynamics with simple flows such as a free shear and a confined Poiseuille flows in Sections 4.1 and 4.2.• In order to quantify migration, we compute a new quantity in Section 4.3, which we call the "pseudolift", that turns out to be an indicative measure of migration.• Lastly, we present phase diagrams for the transport modes in Section 3.3 and investigate the separation in dense RBC suspensions in Section 3.4 for different viscosity contrasts, capillary numbers and device configurations. The efficiency of DLD for dense suspensions in deep devices has not been studied experimentally and numerically. However, it is essential to investigate the dense suspension regime because the deep devices with dense suspensions provide higher throughput than the shallow devices with dilute suspensions.Methodology. We use a standard 2D mechanical model for RBCs [33,40,43...

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Section: Resultssupporting

confidence: 92%

Section: Contributionssupporting

confidence: 90%

Section: Related Workmentioning

confidence: 99%

Section: Dld Modelmentioning

confidence: 99%

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Sorting same-size red blood cells in deep deterministic lateral displacement devices

Kabacaoglu

Biros

2018

J. Fluid Mech.

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“…Performing simulations of cell sorting in a whole device is computationally very expensive even for a single simulation, let alone for optimization. In order to evade the computational cost the numerical studies for the simulation of DLD reduced the simulation domain to a single pillar by assuming periodic boundary conditions [22,30,38,39,42]. Such boundary conditions are tantamount to imposing artificial vertical pressure difference to enforce no net vertical flow [5,42].…”

Section: Dld Modelmentioning

confidence: 99%

Optimal design of deterministic lateral displacement device for viscosity-contrast-based cell sorting

Kabacaoglu

Biros

2018

Phys. Rev. Fluids

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We solve a design optimization problem for deterministic lateral displacement (DLD) device to sort samesize biological cells by their deformability, in particular to sort red blood cells (RBCs) by their viscosity contrast between the fluid in the interior and the exterior of the cells. A DLD device optimized for efficient cell sorting enables rapid medical diagnoses of several diseases such as malaria since infected cells are stiffer than their healthy counterparts. The device consists of pillar arrays in which pillar rows are tilted and hence are not orthogonal to the columns. This arrangement leads cells to have different final vertical displacements depending on their deformability, therefore, it vertically separates the cells. Pillar cross section, tilt angle of the pillar rows and center-to-center distances between pillars are free design parameters. For a given pair of viscosity contrast values of the cells we seek optimal DLD designs by fixing the tilt angle and the center-to-center distances. So the only design parameter is the pillar cross section. We propose an objective function such that a design minimizing it delivers designs providing efficient cell sorting. The objective function is evaluated by simulating the cell flows through a device using our 2D model (Kabacaoglu et al. [Journal of Computational Physics, 357:43-77, 2018]). We solve the optimization problem using a stochastic optimization algorithm. Since the algorithm converges in O(1000) iterations and our high-fidelity DLD model is expensive to evaluate the objective function, we propose a low-fidelity DLD model to enable fast solution of the problem. Finally, we present several scenarios where solving the optimization problem finds designs that can separate cells with similar viscosity contrast values. These designs have cross sections that have features similar to a triangle. To the best of our knowledge, this is the first study which poses designing a DLD device as a constrained optimization problem so as to discover optimal designs systematically.

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Bending and low‐frequency vortex shedding of flexible cylinders in laminar shear flow

Derksen

2021

AIChE Journal

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Simulations of the interaction between flexible cylinders attached to a solid surface and a laminar shear flow have been performed. The flow simulations fully resolve the geometrical details and are based on the lattice-Boltzmann method. An immersed boundary method is used to impose the no-slip conditions at the cylinder surfaces and to determine the distribution of hydrodynamic forces over the cylinder. The latter are responsible for the bending deformation of the cylinders. We first study simple shear systems under steady conditions for which experimental data are available that we use for validation. We then study flexible cylinders in Poiseuille flow that exhibit vortex shedding and demonstrate that the flexibility of the cylinders has a pronounced effect on the temporal behavior of the flow system.

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Breakdown of deterministic lateral displacement efficiency for non-dilute suspensions: A numerical study

Cited by 21 publications

References 32 publications

Sorting same-size red blood cells in deep deterministic lateral displacement devices

Sorting same-size red blood cells in deep deterministic lateral displacement devices

Optimal design of deterministic lateral displacement device for viscosity-contrast-based cell sorting

Bending and low‐frequency vortex shedding of flexible cylinders in laminar shear flow

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