Travelling-wave gel dipolophoresis of hydrophobic conducting colloids

IF 1.8 4区物理与天体物理 Q4 CHEMISTRY, PHYSICAL

The European Physical Journal E Pub Date : 2025-05-24 DOI:10.1140/epje/s10189-025-00492-5

Touvia Miloh, Eldad J. Avital

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Abstract

A unified ‘weak-field’ formulation is provided for calculating the combined nonlinear effect of dielectrophoresis and the induced-charge electrophoresis (dipolophoresis) of polarized rigid hydrophobic spherical colloids freely suspended in an electrolyte-saturated Brinkman-hydrogel (porous) medium under a general (direct or alternating currents) non-uniform electric forcing. Explicit expressions for the modified total dipolophoretic mobility of a conducting (metallic) spherical colloid are given in terms of the Brinkman (Darcy), Navier slip, and Debye (screening) length scales. Also presented is a rigorous derivation of the Helmholtz–Smoluchowski slip velocity in terms of these three length scales, including the induced electroosmotic flow field around a hydrophobic rigid colloid embedded in a Brinkman medium that is forced by an arbitrary (non-uniform) ambient electric field. The available solutions for a free (non-porous) electrolyte solution under a uniform forcing and no-slip surface are obtained as limiting cases. For the purpose of illustration, we present and analyse some newly explicit solutions for the mobility and the associated induced-charge electroosmotic velocity field of a slipping colloid set in an effective (hydrogel) porous medium, which is exposed to an ambient ‘sinusoidal’ travelling-wave excitation depending on frequency and wave number.

Graphical abstract

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疏水导电胶体的行波凝胶二极电泳

提供了一个统一的“弱场”公式，用于计算在一般（直流或交流）非均匀电强迫下自由悬浮在电解质饱和布林克曼-水凝胶（多孔）介质中的极化刚性疏水球形胶体的介电泳和诱导电荷电泳（二极电泳）的组合非线性效应。根据布林克曼（达西）、纳维尔滑移和德拜（筛选）长度尺度给出了导电（金属）球形胶体的修正总二疏迁移率的显式表达式。本文还提出了基于这三种长度尺度的Helmholtz-Smoluchowski滑移速度的严格推导，其中包括嵌入布林克曼介质中受任意（非均匀）环境电场强迫的疏水刚性胶体周围的诱导电渗透流场。在均匀强迫和无滑移表面下，获得了自由（无孔）电解质溶液的可用溶液作为极限情况。为了说明的目的，我们提出并分析了有效（水凝胶）多孔介质中滑动胶体组的迁移率和相关诱导电荷电渗透速度场的一些新的显式解，该介质暴露于环境“正弦”行波激励下，取决于频率和波数。图形抽象

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来源期刊

The European Physical Journal E CHEMISTRY, PHYSICAL-MATERIALS SCIENCE, MULTIDISCIPLINARY

CiteScore

2.60

自引率

5.60%

发文量

审稿时长

3 months

期刊介绍： EPJ E publishes papers describing advances in the understanding of physical aspects of Soft, Liquid and Living Systems. Soft matter is a generic term for a large group of condensed, often heterogeneous systems -- often also called complex fluids -- that display a large response to weak external perturbations and that possess properties governed by slow internal dynamics. Flowing matter refers to all systems that can actually flow, from simple to multiphase liquids, from foams to granular matter. Living matter concerns the new physics that emerges from novel insights into the properties and behaviours of living systems. Furthermore, it aims at developing new concepts and quantitative approaches for the study of biological phenomena. Approaches from soft matter physics and statistical physics play a key role in this research. The journal includes reports of experimental, computational and theoretical studies and appeals to the broad interdisciplinary communities including physics, chemistry, biology, mathematics and materials science.