外国电磁学实验论文(北邮学子专供).PDF

APPLIED PHYSICS LETTERS 93, 203901 ?2008? Controlled transport of magnetic particles using soft magnetic patterns Richard S. Conroy,1,2,a? Gary Zabow,1,2 John Moreland,2 and Alan P. Koretsky1 1Laboratory of Functional and Molecular Imaging, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, Maryland 20892, USA 2National Institute of Standards and Technology, 325 Broadway, Boulder, Colorado 80305, USA ?Received 27 June 2008; accepted 27 September 2008; published online 20 November 2008? Inspired by magnetic bubble memory technology, we demonstrate the temporal and spatial manipulation of superparamagnetic beads guided by soft magnetic patterns in a rotating magnetic ?eld. Soft magnetic structures allow complex and repetitive tasks to be performed. As a demonstration, we show cyclic capture and release of antibodies from different micro?uidic streams. ? 2008 American Institute of Physics. ?DOI: 10.1063/1.3009197? Magnetic particle manipulation is important in bioscience because of the need for separation and concentration of biomolecules and cells.1 With the trend toward integrated micro?uidic devices for micrototal analysis, micrometersized superparamagnetic beads provide convenient, scalable and inexpensive methods for trapping and transporting tagged biological entities.2 In addition to separation and concentration in static ?uids, magnetophoresis has been used to bind and release unidirectionally from channels in a micro?uidic system.3 However simultaneous temporal and spatial control of large ensembles of particles are dif?cult to achieve without microscopic patterning. Microfabricated core/coil designs4 and soft magnetic structures5 have been made for catch-and-release temporal separation of superparamagnetic particles. Additionally, microfabricated current carrying wires,6 meshes,7 and micropatterned conductors8 have been used for both trapping and transport of magnetic particles. However, current-driven systems ar