Department of Mechanical Engineering, Indian Institute of Technology, Kharagpur 721302, India.
Phys Rev Lett. 2013 May 3;110(18):184503. doi: 10.1103/PhysRevLett.110.184503.
We discover a nonlinear coupling between the hydrophobicity of a charged substrate and electrokinetic pumping in narrow fluidic confinements. Our analyses demonstrate that the effective electrokinetic transport in nanochannels may get massively amplified over a regime of bare surface potentials and may subsequently get attenuated beyond a threshold surface charging condition because of a complex interplay between reduced hydrodynamic resistance on account of the spontaneous inception of a less dense interfacial phase and ionic transport within the electrical double layer. We also show that the essential physics delineated by our mesoscopic model, when expressed in terms of a simple mathematical formula, agrees remarkably with that portrayed by molecular dynamics simulations. The nontrivial characteristics of the initial increment followed by a decrement of the effective zeta potential with a bare surface potential may open up the realm of hitherto-unexplored operating regimes of electrohydrodynamically actuated nanofluidic devices.
我们发现带电荷的基质疏水性与狭窄流道中的电动泵送之间存在非线性耦合。我们的分析表明，纳米通道中的有效电动输运可能会在裸表面电势范围内得到极大地放大，并且由于界面相密度降低导致的流体动力阻力减小以及双电层内的离子输运之间的复杂相互作用，在超过表面充电条件的阈值之后，有效电动输运可能会衰减。我们还表明，我们的介观模型所描绘的基本物理现象，当用一个简单的数学公式来表示时，与分子动力学模拟所描绘的物理现象非常吻合。有效 ζ 电势随裸表面电势呈现出先增加后减小的非平凡特性，这可能会开拓电动力学驱动的纳米流控装置迄今为止尚未探索的操作模式领域。
