Numerical Analysis of Microfluidic Magnetic Bead Separation Utilizing an Integrated Array of Magnetic Elements Magnetized by a Homogenous Bias Field

S.A. Khashan, E.P. Furlani
United Arab Emirates University and University at Buffalo, US

Keywords: magnetic particle transport, magnetophoresis, magnetophoretic microsystem, magnetic transport, bioseparation


Magnetic particles are finding increasing use in microfluidic and lab-on-a-chip systems especially for bioapplications where they are commonly used to label, sort and separate target biomaterials from a sample. In this presentation we analyze the transport and capture of magnetic beads under continuous flow through a microchannel positioned above an integrated array of soft-magnetic elements. An external field is applied to magnetize the elements, which gives rise to a spatially varying force on the beads as they flow through the channel. We study the dynamics of the beads using a hybrid modeling approach that combines numerical transport analysis with closed-form field analysis. Particle-fluid transport is computed using computational fluid dynamics (CFD), while the magnetic force that governs particle capture is obtained in closed-form. The CFD analysis takes into account dominant particle forces and two-way momentum transfer between the beads and the fluid. We use the model to analyze the capture efficiency (CE) of the system as a function of different geometry designs. The design variants considered include the volume of the magnetic elements, their aspect ratio and the gaps between neighboring elements. We also discuss the effects of particle fluid coupling and applications of this to micro-mixing.