(286a) Separating Magnetically Labeled and Unlabeled Biological Cells within Microfluidic Channels Using Magnetic Nanodisks

The transport of microscopic objects that rely on magnetic forces has numerous advantages including flexibility of controlling many design parameters and the long range magnetic interactions generally do not adversely affect biological or chemical interactions. We present results on the use of magnetic micro-arrays imprinted within microfluidic channels that benefit from of these features and the ability to rapidly reprogram the magnetic energy landscape for cell manipulation and sorting applications. A central enabling feature is the very large, tunable, magnetic field gradients (> 10⁵ T/m), designed within the microfluidic architecture. These gradients are created with circular permalloy disks and  linear wires (40 nm thick) which are patterned on silicon surfaces using lithographic technology.^1,2  Through use of magnetic microsphere tethers to label biological cells, results on the transport and sorting of heterogeneous cell populations will be presented. The role of micro-array design parameters, competing magnetic forces and hydrodynamic drag forces as well as cell-labeling efficiency in the effectiveness of cell separation will be discussed.

1. Henighan, T., Chen, A., Vieira, G., Hauser, A.J., Yang, F.Y., Chalmers, J.J., Sooryakumar, R.  Transporting Biological Cells via Programmable Mobile Magnetic Traps.  Biophys J.. 98(3):412-417. 2010.  PMID: 20141754
2. Vieira, G., Heninghan, T., Chen, A., Hauser, A.J., Yang, Y., Chalmers, J.J., Sooryakumar, R.  Magnetic wire traps and programmable manipulation of biological cells.  Physical Review Letters, 103:128101, 2009.