Shevkoplyas Sergey S, Siegel Adam C, Westervelt Robert M, Prentiss Mara G, Whitesides George M
Department of Chemistry and Chemical Biology, Harvard University, 12 Oxford St., Cambridge, MA 02138, USA.
Lab Chip. 2007 Oct;7(10):1294-302. doi: 10.1039/b705045c. Epub 2007 Jul 25.
This paper describes a model of the motion of superparamagnetic beads in a microfluidic channel under the influence of a weak magnetic field produced by an electric current passing through a coplanar metal wire. The model based on the conventional expression for the magnetic force experienced by a superparamagnetic bead (suspended in a biologically relevant medium) and the parameters provided by the manufacturer failed to match the experimental data. To fit the data to the model, it was necessary to modify the conventional expression for the force to account for the non-zero initial magnetization of the beads, and to use the initial magnetization and the magnetic susceptibility of the beads as adjustable parameters. The best-fit value of susceptibility deviated significantly from the value provided by the manufacturer, but was in good agreement with the value computed using the magnetization curves measured independently for the beads from the same vial as those used in the experiment. The results of this study will be useful to researchers who need an accurate prediction of the behavior of superparamagnetic beads in aqueous suspensions under the influence of weak magnetic fields. The derivation of the force on a magnetic bead due to a magnetic field also identifies the correct treatment to use for this interaction, and resolves discrepancies present throughout the literature.
本文描述了超顺磁性微珠在微流控通道中运动的模型，该通道受到由通过共面金属线的电流产生的弱磁场影响。基于超顺磁性微珠（悬浮在生物相关介质中）所受磁力的传统表达式以及制造商提供的参数构建的模型，未能与实验数据匹配。为使数据与模型拟合，有必要修改力的传统表达式，以考虑微珠的非零初始磁化强度，并将微珠的初始磁化强度和磁化率用作可调参数。磁化率的最佳拟合值与制造商提供的值有显著偏差，但与使用从与实验中所用微珠来自同一小瓶中独立测量的磁化曲线计算得到的值高度一致。这项研究的结果将对那些需要准确预测超顺磁性微珠在弱磁场影响下在水悬浮液中行为的研究人员有用。磁场作用于磁珠的力的推导也确定了用于这种相互作用的正确处理方法，并解决了整个文献中存在的差异。
