Impact of Water-Depletion Layer on Transport in Hydrophobic Nanochannels
Impact of Water-Depletion Layer on Transport in Hydrophobic Nanochannels
复制标题
缺水层对疏水纳米通道中传输的影响
DOI：
10.1021/acs.analchem.5b03061
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发表时间：
2015
影响因子：
7.4
通讯作者：
Masateru Taniguchi
中科院分区：
文献类型：
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作者：
Yuhui He;Makusu Tsutsui;Xiang Shui Miao;Masateru Taniguchi
最近的实验表明，通过用疏水性材料制造纳米流体通道，电渗流（electroosmotic flow，EVOF）和离子电流的测量幅度显著偏离传统的电动力学建模指示。在这些意想不到的观察，复杂的依赖性的沟道壁的表面电荷浓度仍然是最混乱的。在这项工作中，我们给出了一个完整的和统一的图片的现象，概述了竞争的两种机制，在水耗尽层周围的通道壁：减少的趋势，由于净电荷的重新分配的流体流量，和增加的趋势，因为降低溶液粘度。我们的定量评估表明，交替主导的两种机制导致所观察到的输运行为。此外，通过考虑耗尽层中离子迁移率的降低，我们的计算与使用BN纳米管通道的最新实验定量一致。
Recent experiments showed that by fabricating nanofluidic channels with hydrophobic materials, the measured amplitudes of both electroosmotic flow (EOF) and ionic current deviated significantly from the conventional electrokinetic modeling indication. Among these unexpected observations, the complicated dependence of EOF on the surface charge concentration of the channel wall remains most confusing. In this work we give a complete and unified picture for the phenomena by outlining the competing two mechanisms in the water-depletion layer around the channel wall: the decreasing trend of fluidic flow due to the redistribution of net charges, and the increasing trend because of the reduced solution viscosity there. Our quantitative evaluation illustrates that the alternate dominating by the two mechanisms leads to the observed transport behaviors. Furthermore, by considering the decreasing of ionic mobility in the depletion layer, our calculations show quantitative agreement with the latest experiments using BN nanotube channels.