1 research outputs found
Optimal design of deterministic lateral displacement device for viscosity contrast based cell sorting
We solve a design optimization problem for deterministic lateral displacement
(DLD) device to sort same-size 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 define a unique device. 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 which we parameterize with uniform 5th order B-splines. We propose an
objective function to try to capture efficient cell sorting. The objective
function is evaluated by simulating the cell flows through a device using our
2D model based on a boundary integral method (Kabacaoglu et al. Journal of
Computational Physics, 357:43-77, 2018). We solve the optimization problem
using the covariance matrix adaptation evolution strategy (CMA-ES), which is a
stochastic, derivative-free algorithm. We present several scenarios where
solving the optimization problem finds designs that can separate cells with
similar viscosity contrast values. To the best of our knowledge, this is the
first study which poses designing a DLD device as a constrained optimization
problem and shows that solving this problem systematically discovers optimal
designs.Comment: 28 page