Vlassiouk Ivan, Smirnov Sergei, Siwy Zuzanna
Department of Physics and Astronomy, University of California, Irvine, California 92697, USA.
Nano Lett. 2008 Jul;8(7):1978-85. doi: 10.1021/nl800949k. Epub 2008 Jun 18.
There has been an increasing interest in single nanochannel ionic devices, such as ionic filters that control the type of transported ions and ionic diodes that rectify the ionic flow. In this article, we theoretically investigate the importance of the dimensions, surface charge, electrolyte concentration, and applied bias on nanopore performance. We compare numerical solutions of the Poisson, Nernst-Planck (PNP), and Navier-Stokes (NS) equations with their one-dimensional, analytical approximations. We show that by decreasing the length of the nanopore, the ionic current and ionic selectivity become affected by processes outside the nanochannel. The contribution of electroosmosis is noticeable, especially for highly charged nanochannels, but is insignificant, justifying the use of the simple one-dimensional approximation in many cases. Estimates for the critical electric field at which the nanopore selectivity decreases and the ion current starts to saturate are provided.
人们对单纳米通道离子器件的兴趣与日俱增，比如能够控制传输离子类型的离子过滤器以及能使离子流整流的离子二极管。在本文中，我们从理论上研究了尺寸、表面电荷、电解质浓度和外加偏压对纳米孔性能的重要性。我们将泊松方程、能斯特 - 普朗克方程（PNP）和纳维 - 斯托克斯方程（NS）的数值解与其一维解析近似进行了比较。我们表明，通过减小纳米孔的长度，离子电流和离子选择性会受到纳米通道外部过程的影响。电渗作用的贡献很显著，特别是对于高电荷纳米通道，但在许多情况下并不重要，这证明了在很多情形下使用简单一维近似的合理性。文中还给出了纳米孔选择性降低且离子电流开始饱和时的临界电场估计值。
