Liu Y, Liu M, Lau W M, Yang J
Department of Mechanical and Materials Engineering and Surface Science Western, University of Western Ontario, London, Ontario, N6A 5B7, Canada.
Langmuir. 2008 Mar 18;24(6):2884-91. doi: 10.1021/la702059v. Epub 2008 Feb 1.
Electrokinetic phenomena play a major role in microfluidic systems, and such a role becomes even more significant in nanofluidic systems due to the increase of the surface-to-volume ratio. Description of the electric double layer (EDL) at a solid-liquid interface is the key to understand and utilize electrokinetic phenomena. However, the traditional Gouy-Chapman (GC) theory for the EDL, which has been successfully used in many microfluidic applications, does not include some important characteristics such as ion size and image effect. These characteristics are indeed important in nanofluidics. This paper explores the impacts of ion size and the image effect on micro- and nanoscale electrokinetic flows. An advanced theory, the modified Poisson-Boltzmann (MPB) theory proposed by Outhwaite and his co-workers,1,26 is adopted to describe the EDL. Electrokinetic flows in micro- and nanochannels are reinvestigated. The results show that ion size has significant effects on electrokinetic flows in nanosystems in terms of both the flow field and the streaming potential, while the image effect only significantly affects the streaming potential.
电动现象在微流体系统中起着重要作用，由于表面积与体积比的增加，这种作用在纳米流体系统中变得更加显著。描述固液界面处的双电层（EDL）是理解和利用电动现象的关键。然而，传统的用于双电层的 Gouy-Chapman（GC）理论，虽然已成功应用于许多微流体应用中，但并未包含一些重要特性，如离子大小和镜像效应。这些特性在纳米流体学中确实很重要。本文探讨了离子大小和镜像效应对微米和纳米尺度电动流动的影响。采用了一种先进的理论，即由Outhwaite及其同事提出的修正泊松-玻尔兹曼（MPB）理论，来描述双电层。对微米和纳米通道中的电动流动进行了重新研究。结果表明，离子大小在流场和流动电势方面对纳米系统中的电动流动都有显著影响，而镜像效应仅对流动电势有显著影响。
