Xuan Xiangchun, Li Dongqing
Department of Mechanical & Industrial Engineering, University of Toronto, Toronto, Ontario, Canada.
Electrophoresis. 2006 Dec;27(24):5020-31. doi: 10.1002/elps.200600031.
The accurate prediction of electrokinetic migration velocity and dispersion is crucial to separating electrophoretically charged solutes in micro- or nanochannels. In this paper, we investigate numerically the influence of transverse electromigration (TEM) on the solute electrokinetic transport in a series of micro- and nanochannels. The TEM, often ignored in previous studies, is demonstrated to significantly affect the solute migration velocity in nanochannels and the electrokinetic dispersion in microchannels. This is because the TEM can force either positively charged solutes into or negatively charged solutes out of the electrical double layer that forms adjacent to the negatively charged channel wall and contains the velocity gradients. Analytical solutions are also derived for characterizing the electrokinetic transport of charged solutes in nanochannels, which has been validated to be in good agreement with the numerical simulation. Moreover, we demonstrate that the proposed analytical formula for the solute migration velocity actually applies to channels of any size.
准确预测电动迁移速度和扩散对于在微通道或纳米通道中分离电泳带电溶质至关重要。在本文中，我们通过数值研究了横向电迁移（TEM）对一系列微通道和纳米通道中溶质电动输运的影响。横向电迁移在以往研究中常被忽略，结果表明它会显著影响纳米通道中溶质的迁移速度以及微通道中的电动扩散。这是因为横向电迁移能够迫使带正电的溶质进入或带负电的溶质离开与带负电的通道壁相邻形成的、包含速度梯度的双电层。我们还推导了用于表征纳米通道中带电溶质电动输运的解析解，经验证其与数值模拟结果吻合良好。此外，我们证明了所提出的溶质迁移速度解析公式实际上适用于任何尺寸的通道。
