CFD Modelling of Cell Capture in BioMEMs

Abstract

Separation of specific cells from blood stream using paramagnetic/superparamagnetic beads has gained more and more importance in recent times for early diagnosis of several critical diseases. However, the performance immunomagnetophoretic cell sorters (ICS) crucially depends on the design and operational conditions of such, commonly microfluidic, systems. Here, we present a CFD model relying on the Navier-Stokes equations governing the fluid dynamics and continuum descriptions of cell, bead and cell-bead complexes. The spatial-temporal evolution of the concentration fields are governed by convection-diffusion equations for non-magnetic cells and Nerast-Planck type equations for beads and cell-bead complex. The 'reaction' rates between cells, cell-bead 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. The derived CFD model facilitates the design of ICS taking a realistic description of the binding kinetics into account. Exemplarily, we investigate the performance of Y shaped geometry used for contacting of cells and beads.