Microfluidic Immunomagnetic Cell Separation using Shrink Induced Nano-Magnetic Traps
February 10, 2012
Dr. Dharmakeerthi Nawarathna
Department of Biomedical Engineering
University of California, Irvine
Sample preparation critical to most biomedical assays typically requires a separation step, be it DNA purification or the separation of various cell types. The ability to separate target cells from a complex mixture of cells is an important capability in many areas in biomedical engineering such as cell enumeration, cell functional assays and cell based therapies. In immunomagnetic cell separation magnetic particles are first selectively attached to target cells and the target cells are separated from the other cells as they are subjected to magnetophoretic forces from an external magnet. Microfluidic technology can be used to engineer structures that are capable of producing extremely high magnetic field gradients; these field gradients produce magnetophoretic forces in the range of nN on 1mm magnetic beads. Furthermore, these high magnetophoretic forces can be effectively utilized to achieve extremely high throughput cell separation. Unfortunately such microfluidic integration is typically extremely expensive and time consuming. To address that issue, we have fabricated and tested low cost-high performance microfluidic immunomagnetic devices. In our microfluidic system, target cells or particles are trapped inside the microfludic channel using nano-scale magnetic traps fabricated from nickel nano-wrinkles self-assembled in a shape memory polymer. When the cells flow over the externally magnetized magnetic traps, high magnetic field gradients trap magnetically labeled cells inside the microfluidic channel. The trapped cells are collected by turning off the external magnetic field. Preliminary results obtained from separating magnetic beads from binary mixtures of magnetic beads and polystyrene beads produce 98% purity and unprecedented enrichments of 25000 fold.