Magnetic forces produced by rectangular permanent magnets in static microsystems
Magnetic forces produced by rectangular permanent magnets in static microsystems
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DOI：
10.1039/b901865d
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发表时间：
2009-01-01
期刊：
影响因子：
6.1
通讯作者：
Girault, Hubert H.
中科院分区：
文献类型：
--
作者：
Gassner, Anne-Laure;Abonnenc, Melanie;Girault, Hubert H.
在2D几何形状中进行有限元数值模拟，以绘制矩形永磁体产生的磁场和力分布，作为它们相对于微通道的尺寸和位置的函数。一个单一的磁铁，两个磁铁放置在吸引和排斥已被考虑。这项工作的目标是显示磁珠优先捕获在微通道中。这些模拟定性证实，在一个几何的情况下，在毛细管中的磁珠塞形成的微观可视化。结果表明，磁塞的数量与磁结构有关：在吸引时，磁塞位于磁体中间;在排斥时，磁塞位于磁体边缘;在单磁体时，磁塞位于磁体中心。磁体的几何形状（h和l分别是磁体的高度和长度）及其相对间距s对磁通量密度具有显著影响。它在磁体内部的值随着h/l比而增加。因此，条形磁铁比扁平磁铁产生更大和更均匀的值。l/s比也影响微通道中的磁力值，两者对于所有配置都伴随增加。此外，随着l/s比的增加，在吸引配置中出现中间的零力区域，而对于单个磁体，最大值和最小值的数量从一个变为两个，产生两个聚焦区域而不是只有一个。
Finite element numerical simulations were carried out in 2D geometries to map the magnetic field and force distribution produced by rectangular permanent magnets as a function of their size and position with respect to a microchannel. A single magnet, two magnets placed in attraction and in repulsion have been considered. The goal of this work is to show where magnetic beads are preferentially captured in a microchannel. These simulations were qualitatively corroborated, in one geometrical case, by microscopic visualizations of magnetic bead plug formation in a capillary. The results show that the number of plugs is configuration dependent with: in attraction, one plug in the middle of the magnets; in repulsion, two plugs near the edges of the magnets; and with a single magnet, a plug close to the center of the magnet. The geometry of the magnets (h and l are the height and length of the magnets respectively) and their relative spacing s has a significant impact on the magnetic flux density. Its value inside a magnet increases with the h/l ratio. Consequently, bar magnets produce larger and more uniform values than flat magnets. The l/s ratio also influences the magnetic force value in the microchannel, both increasing concomitantly for all the configurations. In addition, a zero force zone in the middle appears in the attraction configuration as the l/s ratio increases, while with a single magnet, the number of maxima and minima goes from one to two, producing two focusing zones instead of only one.