Abstract
We solve a design optimization problem for a deterministic lateral displacement (DLD) device to sort same-size biological cells by their deformability, in particular to sort red blood cells 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 and therefore it vertically separates the cells. The pillar cross section, the tilt angle of the pillar rows, and the 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 provides efficient cell sorting. The objective function is evaluated by simulating the cell flows through a device using our two-dimensional model [Kabacaoğlu et al., J. Comput. Phys. 357, 43 (2018)]. We solve the optimization problem using a stochastic optimization algorithm. Since the algorithm converges in iterations and our high-fidelity DLD model is expensive to evaluate the objective function, we propose a low-fidelity DLD model that enables 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.
7 More- Received 22 May 2018
DOI:https://doi.org/10.1103/PhysRevFluids.3.124201
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