Langmuir. 2018 Jul 3;34(26):7916-7921. doi: 10.1021/acs.langmuir.8b00932. Epub 2018 Jun 25.
Ionic current through a microchannel has drawn significant attention not only for fundamental electrokinetic research but also for the development of novel micro/nanofluidic applications. Among various ion transport mechanisms, surface conduction, which is a predominant mechanism in micro/nanofluidic devices, has been theoretically characterized based on two-dimensional analysis. However, its infinite axis assumption has become a barrier for direct application in practical micro/nanochannel networks. In this work, we conducted rigorous experiments to include all of the three-dimensional length scales. There, L/ A, the perimeter to area ratio of the microchannel cross-section, came up as a single parameter to quantitatively interpret the surface conductive ion transportation. Overlimiting conductance of microchannel devices increased with larger perimeter, which is equivalent to specific surface area, even with the same cross sectional area. Finally, a micro/nanofluidic diode with a different L/ A value on its forward and reverse channel was demonstrated as a simple application. The analysis presented could provide a practical guideline to design a micro/nanofluidic application.
离子在微通道中的电流不仅引起了人们对基本电动研究的极大关注，也引起了对新型微纳流应用的开发的关注。在各种离子输运机制中，表面传导是微纳流设备中的主要机制，已经基于二维分析进行了理论描述。然而，其无限轴的假设成为了在实际微纳米通道网络中直接应用的障碍。在这项工作中，我们进行了严格的实验，包括了所有的三维长度尺度。在这里，微通道横截面的周长与面积比 L/A 作为一个单一参数，定量解释了表面传导离子输运。微通道器件的超导电导率随着周长的增加而增加，这相当于比表面积，即使在相同的横截面积下也是如此。最后，展示了一个具有不同 L/A 值的正向和反向通道的微纳流二极管作为一个简单的应用。所提出的分析可以为微纳流应用的设计提供实际指导。
