Université Paris-Saclay, CNRS, Centre de Nanosciences et Nanotechnologies, Palaiseau, France.
Department of Mechanical Engineering, University of California Santa Barbara, Santa Barbara, CA, USA.
Electrophoresis. 2022 Mar;43(5-6):741-751. doi: 10.1002/elps.202100297. Epub 2022 Jan 30.
We report on the investigation of electropreconcentration phenomena in micro-/nanofluidic devices integrating 100 μm long nanochannels using 2D COMSOL simulations based on the coupled Poisson-Nernst-Planck and Navier-Stokes system of equations. Our numerical model is used to demonstrate the influence of key governing parameters such as electrolyte concentration, surface charge density, and applied axial electric field on ion concentration polarization (ICP) dynamics in our system. Under sufficiently extreme surface-charge-governed transport conditions, ICP propagation is shown to enable various transient and stationary stacking and counter-flow gradient focusing mechanisms of anionic analytes. We resolve these spatiotemporal dynamics of analytes and electrolyte ICP over disparate time and length scales, and confirm previous findings that the greatest enhancement is observed when a system is tuned for analyte focusing at the charge, excluding microchannel, nanochannel electrical double layer (EDL) interface. Moreover, we demonstrate that such tuning can readily be achieved by including additional nanochannels oriented parallel to the electric field between two microchannels, effectively increasing the overall perm-selectivity and leading to enhanced focusing at the EDL interfaces. This approach shows promise in providing added control over the extent of ICP in electrokinetic systems, particularly under circumstances in which relatively weak ICP effects are observed using only a single channel.
我们报告了使用基于耦合泊松-纳维-斯托克斯和纳维-斯托克斯系统方程的二维 COMSOL 模拟，对集成 100 μm 长纳米通道的微纳流控装置中的电预浓缩现象进行了研究。我们的数值模型用于演示关键控制参数（如电解质浓度、表面电荷密度和施加的轴向电场）对系统中离子浓度极化（ICP）动力学的影响。在足够极端的表面电荷控制传输条件下，ICP 传播显示出能够实现阴离子分析物的各种瞬态和稳态堆积和逆流梯度聚焦机制。我们解析了分析物和电解质 ICP 在不同时间和长度尺度上的时空动力学，并证实了先前的发现，即在调谐系统以在电荷处聚焦分析物（排除微通道、纳米通道电双层 (EDL) 界面）时，观察到最大增强。此外，我们证明，通过包括平行于两个微通道之间电场的额外纳米通道，很容易实现这种调谐，从而有效提高 EDL 界面处的整体选择性并导致增强聚焦。这种方法有望在电动力学系统中提供对 ICP 程度的额外控制，特别是在仅使用单个通道观察到相对较弱的 ICP 效应的情况下。
