Immunomagnetic Separation and Transport of Magnetic Beads in Microfluidic Field Flow Fractionation Devices for Bio-MEMS Application

Abstract

Immunomagnetic isolation of biochemical and organic entities in a microfluidic environment is a popular tool for a wide range of bioMEMS applications, including biosensors. Numerical analyses of magnetophoretic separation and capture of magnetic microspheres in microfluidic field flow fractionation devices under the influence of line dipoles are presented in this work. Microchannel flow and magnetic beads are simulated for different values of dipole strength and position in the microchannel configurations. Magnetic beads based microfluidics offer great potential towards overcoming the major challenges involved with the design of lab-on-a-chip devices. Various bio-cells conjugated magnetic beads are separated at different outlet due to the different mobility by the field flow fraction technique. Two dipoles having different strength are placed near the bottom wall of micro-channel. Thus two different field is generated which leads to separation of magnetic particles. The objective of the device is to collect maximum number of particles in its designated outlet with as little as possible intermixing between particles. The device performance is designated in terms of capture efficiencies at outlet-1 and outlet-2. It is expected that only larger particles are captured at outlet-1 and smaller particles are captured at outlet-2 but there is possibility of mixing in both of outlets. That means that both types of particles are captured in both outlets. In that case two additional parameters such as separation index at outlet-1 and outlet-2 are required to measure the extent of separation of particles. Transport and field flow fractionation of magnetic microparticles subject to a magnetic field gradient in a microfluidic channel is investigated through a numerical simulation using an Eulerian-Lagrangian approach.