Three-dimensional CFD modelling of a continuous immunomagnetophoretic cell capture in BioMEMs

Separation of rare cells from blood stream using paramagnetic/superparamagnetic beads in microfluidic device has gained importance in recent years for early diagnosis of several critical diseases. However, the performance of immunomagnetophoretic cell sorters (ICS) crucially depends on their design and operational conditions. Here, we present a three-dimensional CFD model based on the Navier–Stokes equations governing the fluid dynamics and continuum descriptions for the cell, bead and cell–bead complexes for a continuous ICS. The spatial-temporal evolution of the concentration fields are governed by convection–diffusion equations for non-magnetic cells and Nernst–Planck type equations for beads and cell–bead(s) complexes. The attachment rates between cells, cell–bead(s) complexes and beads are deduced from the collision probabilities which are derived by means of classical scattering theory. The CFD model is used to investigate the performance of a generic continuous cell separation system. Since the cells are larger in diameter, more than one bead can get attached to the cells. Multiple beads binding to the cell has been considered in this study, which has not been reported in literature till date. Exemplarily, we investigate the performance of Y-shaped geometry used for contacting of cells and beads.