Cheng Kuang-Ling, Sheng Yu-Jane, Jiang Shaoyi, Tsao Heng-Kwong
Department of Chemical Engineering, National Taiwan University, Taipei, Taiwan, ROC.
J Chem Phys. 2008 Mar 14;128(10):101101. doi: 10.1063/1.2890960.
The size separation of Brownian particles with the same free mobility in an electrophoretic microchannel with alternating thick regions and narrow constrictions is studied theoretically. The electrophoretic mobility is field dependent and generally increases with field strength. In weak fields, Brownian diffusion dominates and the migration is controlled by the entrance effect. Therefore, smaller particles migrate faster than larger ones. In strong fields, however, the particle tends to follow electric field lines. Smaller particles are susceptible to Brownian motion and thus influenced by the nonuniform electric field in the well significantly. As a result, larger particles possess higher mobilities. Our simulation results agree with the experimental observations and provide guidance for efficient nanofluidic separation.
理论上研究了在具有交替的厚区域和狭窄收缩处的电泳微通道中具有相同自由迁移率的布朗粒子的尺寸分离。电泳迁移率取决于电场，通常随场强增加而增大。在弱场中，布朗扩散起主导作用，迁移受入口效应控制。因此，较小的粒子比较大的粒子迁移得更快。然而，在强场中，粒子倾向于沿电场线移动。较小的粒子易受布朗运动影响，因此在阱中受到非均匀电场的显著影响。结果，较大的粒子具有更高的迁移率。我们的模拟结果与实验观察结果一致，并为高效的纳米流体分离提供了指导。
