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Diamagnetic repulsion—A versatile tool for label-free particle handling in microfluidic devices

Peyman, Sally A.; Kwan, Er Yee; Margarson, Oliver; Iles, Alexander; Pamme, Nicole


Sally A. Peyman

Er Yee Kwan

Oliver Margarson

Alexander Iles

Nicole Pamme


We report the exploration of diamagnetic repulsion forces for the selective manipulation of microparticles inside microfluidic devices. Diamagnetic materials such as polymers are repelled from magnetic fields, an effect greatly enhanced by suspending a diamagnetic object in a paramagnetic Mn2+ solution. The versatility of diamagnetic repulsion is demonstrated for the trapping, focussing and deflection of polystyrene particles for three example applications. Firstly, magnet pairs with unlike poles facing each other were arranged along a microcapillary to trap plugs of differently functionalised particles for a simultaneous surface-based assay in which biotin was selectively bound to a plug of streptavidin coated particles utilising only 22nL of reagent. Secondly, by slightly modifying the magnetic field design, the rapid focussing of particles into a narrow central stream at a flow rate of 650μms-1 was accomplished for particle pre-concentration. In a third application, 5 and 10μm polystyrene particles were separated from each other in continuous flow by passing the particle mixture through a microfluidic chamber with a perpendicular magnetic field, a method termed diamagnetophoresis. The separation was investigated between flow rates of 20-100μLh-1, with full resolution of the particle populations being achieved at 20μLh-1. These experiments show the potential of diamagnetic repulsion for simple, label-free manipulation of particles and other diamagnetic objects such as cells for a range of bioanalytical techniques.


Peyman, S. A., Kwan, E. Y., Margarson, O., Iles, A., & Pamme, N. (2009). Diamagnetic repulsion—A versatile tool for label-free particle handling in microfluidic devices. Journal of Chromatography A, 1216(52), 9055-9062.

Journal Article Type Article
Online Publication Date Jun 18, 2009
Publication Date Dec 25, 2009
Deposit Date Nov 13, 2014
Journal Journal Of Chromatography A
Print ISSN 0021-9673
Publisher Elsevier
Peer Reviewed Peer Reviewed
Volume 1216
Issue 52
Pages 9055-9062
Keywords Organic Chemistry; Analytical Chemistry; Biochemistry; General Medicine
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