Colloid Electrophoresis for Strong and Weak Ion Diffusivity

Giupponi, Giovanni; Pagonabarraga, Ignacio

doi:10.1103/physrevlett.106.248304

Cited by 28 publications

(37 citation statements)

References 24 publications

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“…Particle separation techniques use the fact that the particles' response to external stimuli, such as gradients or fields, depends on their physical properties like surface charges, magnetization, size or shape [9,10]. Accordingly, conventional methods for filtering particles involve centrifugal fractionation [11], phoretic forces [12,13] or external fields [14]. Recently, novel devices for particle separation were proposed [9,10,[15][16][17].…”

Section: Introductionmentioning

confidence: 99%

Giant enhancement of hydrodynamically enforced entropic trapping in thin channels

Martens

Straube

Schmid

et al. 2014

Eur. Phys. J. Spec. Top.

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Using our generalized Fick-Jacobs approach [1,2] and extensive Brownian dynamics simulations, we study particle transport through three-dimensional periodic channels of different height. Directed motion is caused by the interplay of constant bias acting along the channel axis and a pressure-driven flow. The tremendous change of the flow profile shape in channel direction with the channel height is reflected in a crucial dependence of the mean particle velocity and the effective diffusion coefficient on the channel height. In particular, we observe a giant suppression of the effective diffusivity in thin channels; four orders of magnitude compared to the bulk value.

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Section: Introductionmentioning

confidence: 99%

Giant enhancement of hydrodynamically enforced entropic trapping in thin channels

Martens

Straube

Schmid

et al. 2014

Eur. Phys. J. Spec. Top.

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“…Our smoothing results in a further increase of less than 10% in time, when compared to the nonsmoothed moving boundaries. Together, this shows that our method does not incur an unreasonable computational cost and can therefore be straightforwardly applied to domain sizes that are currently accessible to the Capuani et al method 32,50 .…”

Section: A Electrophoresis Of a Single Colloidmentioning

confidence: 73%

“…Specifically, we simulate a single, homogeneously charged, spherical colloid in a cubic box with periodic boundary conditions (PBCs) undergoing electrophoresis in a uniform external electric field. This system has already been studied extensively using the EK method without moving boundaries by considering the equivalent problem of electro-osmotic flow 50 .…”

Section: A Electrophoresis Of a Single Colloidmentioning

confidence: 99%

Moving charged particles in lattice Boltzmann-based electrokinetics

Kuron

Rempfer

Schornbaum

et al. 2016

The Journal of Chemical Physics

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The motion of ionic solutes and charged particles under the influence of an electric field and the ensuing hydrodynamic flow of the underlying solvent is ubiquitous in aqueous colloidal suspensions. The physics of such systems is described by a coupled set of differential equations, along with boundary conditions, collectively referred to as the electrokinetic equations. Capuani et al. [J. Chem. Phys. 121, 973 (2004)] introduced a lattice-based method for solving this system of equations, which builds upon the lattice Boltzmann algorithm for the simulation of hydrodynamic flow and exploits computational locality. However, thus far, a description of how to incorporate moving boundary conditions into the Capuani scheme has been lacking. Moving boundary conditions are needed to simulate multiple arbitrarily moving colloids. In this paper, we detail how to introduce such a particle coupling scheme, based on an analogue to the moving boundary method for the pure lattice Boltzmann solver. The key ingredients in our method are mass and charge conservation for the solute species and a partial-volume smoothing of the solute fluxes to minimize discretization artifacts. We demonstrate our algorithm's effectiveness by simulating the electrophoresis of charged spheres in an external field; for a single sphere we compare to the equivalent electro-osmotic (co-moving) problem. Our method's efficiency and ease of implementation should prove beneficial to future simulations of the dynamics in a wide range of complex nanoscopic and colloidal systems that were previously inaccessible to lattice-based continuum algorithms.

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“…This similarity is expected because of the small magnitude of the perturbing electric field and colloid Péclet number, Pe = av coll /D ± , where v coll is the velocity of the colloid at steady state. For Pe ≥ 1, the deformation of the salt cloud around the colloid induces significant deviations in the electrophoretic mobility [19]; we can hence envisage a corresponding departure of the dynamic z from its equilibrium counterpart. Typically, as for simulations here, Pe 1 and particle mobility does not depend on Pe, hence the measured z values at equilibrium and steady state are statistically indistinguishable.…”

Section: Resultsmentioning

confidence: 88%

Determination of the zeta potential for highly charged colloidal suspensions

Giupponi

Pagonabarraga

2011

Phil. Trans. R. Soc. A.

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We compute the electrostatic potential at the surface, or zeta potential z, of a charged particle embedded in a colloidal suspension using a hybrid mesoscopic model. We show that, for weakly perturbing electric fields, the value of z obtained at steady state during electrophoresis is statistically indistinguishable from z in thermodynamic equilibrium. We quantify the effect of counter-ion concentration on z. We also evaluate the relevance of the lattice resolution for the calculation of z and discuss how to identify the effective electrostatic radius.

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Colloid Electrophoresis for Strong and Weak Ion Diffusivity

Cited by 28 publications

References 24 publications

Giant enhancement of hydrodynamically enforced entropic trapping in thin channels

Giant enhancement of hydrodynamically enforced entropic trapping in thin channels

Moving charged particles in lattice Boltzmann-based electrokinetics

Determination of the zeta potential for highly charged colloidal suspensions

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