Electrophoresis of a colloidal sphere with double-layer polarization in a microtube

Chiu, Han C.; Keh, Huan J.

doi:10.1007/s10404-016-1728-z

Cited by 10 publications

(11 citation statements)

References 24 publications

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“…3. A few recent experimental studies have confirmed the previous theoretically predicted nonlinear electrophoresis in Newtonian fluids [192][193][194][195][196][197][198][199], which takes place if the applied DC electric field is sufficient highly [200][201][202]. Particularly interesting is the work from Cardenas-Benitez et al [203], who reported the observation of particle flow reversal when the applied DC electric field is beyond a threshold magnitude.…”

Section: Current Idep Microdevices Have Been Limited To Worksupporting

confidence: 52%

Review of nonlinear electrokinetic flows in insulator‐based dielectrophoresis: From induced charge to Joule heating effects

Xuan

2021

Electrophoresis

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Insulator‐based dielectrophoresis (iDEP) has been increasingly used for particle manipulation in various microfluidic applications. It exploits insulating structures to constrict and/or curve electric field lines to generate field gradients for particle dielectrophoresis. However, the presence of these insulators, especially those with sharp edges, causes two nonlinear electrokinetic flows, which, if sufficiently strong, may disturb the otherwise linear electrokinetic motion of particles and affect the iDEP performance. One is induced charge electroosmotic (ICEO) flow because of the polarization of the insulators, and the other is electrothermal flow because of the amplified Joule heating in the fluid around the insulators. Both flows vary nonlinearly with the applied electric field (either DC or AC) and exhibit in the form of fluid vortices, which have been utilized to promote some applications while being suppressed in others. The effectiveness of iDEP benefits from a comprehensive understanding of the nonlinear electrokinetic flows, which is complicated by the involvement of the entire iDEP device into electric polarization and thermal diffusion. This article is aimed to review the works on both the fundamentals and applications of ICEO and electrothermal flows in iDEP microdevices. A personal perspective of some future research directions in the field is also given.

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Section: Current Idep Microdevices Have Been Limited To Worksupporting

confidence: 52%

Review of nonlinear electrokinetic flows in insulator‐based dielectrophoresis: From induced charge to Joule heating effects

Xuan

2021

Electrophoresis

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“…Having established an estimate for the surface charge density, the particle velocity in high fields was characterized using a microfluidic channel. Hydrodynamic and electric wall effects were negligible in this wide channel since the channel height and width were large enough [15]. The two types of particles (PS 620 nm and PMMA 520 nm) were suspended in 1 mM KCl.…”

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confidence: 99%

Nonlinear Electrophoresis of Highly Charged Nonpolarizable Particles

et al. 2019

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Nonlinear field dependence of electrophoresis in high fields has been investigated theoretically, yet experimental studies have failed to reach consensus on the effect. In this work, we present a systematic study on the nonlinear electrophoresis of highly charged submicron particles in applied electric fields of up to several kV/cm. First, the particles are characterized in the low-field regime at different salt concentrations and the surface charge density is estimated. Subsequently, we use microfluidic channels and video tracking to systematically characterize the nonlinear response over a range of field strengths. Using velocity measurements on the single particle level, we prove that nonlinear effects are present at electric fields and surface charge densities that are accessible in practical conditions. Finally, we show that nonlinear behavior leads to unexpected particle trapping in channels. :1907.04278v1 [cond-mat.soft] arXiv

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“…The boundary collocation technique can be used to satisfy Eq. at M points over a quarter–circular longitudinal arc of the charged sphere in the tube (with geometrical symmetries) and truncate the infinite series in Eq.…”

Section: Methodsmentioning

confidence: 99%

“…The hydrodynamic force acting on the particle is given by

F = 4 π η D_{2}

, in which only the lowest–order constant D 2 is involved. This force must vanish for the freely suspended particle, viz.…”

Section: Methodsmentioning

confidence: 99%

“…and leads to

U^{(1)} = false[(d_{1} G + d_{2} + d_{4} H) λ^{3} + d_{3} (1 + 2 H) λ^{5} false] U_{0} {bolde}_{normalz},

where

\begin{matrix} left G & left = & left \frac{1}{U_{0}} \sum_{m = 1}^{2} \sum_{i = 1}^{2} G_{normalm} g_{mi} |\nabla μ_{i \infty}| \\ left = \frac{k T |\nabla n^{\infty}|}{U_{0} n_{0}^{\infty}} \sum_{m = 1}^{2} G_{m} b_{m}, \end{matrix}

and the constants d j are given by the Eq. (45) of Chiu and Keh . The effect of the wall–reflected fields, which is

O (λ^{3})

, can enhance or retard the particle migration, even for an uncharged tube wall, depending on the values of G and λ.…”

Section: Appendix A: Analysis Of the Diffusiophoresis Of A Dielectricmentioning

confidence: 99%

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Diffusiophoresis of a charged particle in a microtube

Chiu

Keh

2017

Electrophoresis

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The diffusiophoresis of a charged sphere along the axis of a circular microtube filled with an electrolyte solution is studied theoretically. The tube wall may be either nonconductive and impermeable or prescribed with a linear electrolyte concentration distribution. The electric double layers at the solid surfaces are thin, but the diffuse-layer polarization effect over the particle surface is considered. The general solutions to the electrokinetic differential equations are expressed in spherical and cylindrical coordinates, whereas the boundary conditions at the particle surface are satisfied by a collocation technique. The collocation solutions for the diffusiophoretic velocity of the particle, which are in good agreement with the asymptotic formula derived from a reflection method, are obtained for various values of the radius ratio and zeta potential ratio between the particle and the microtube and of other relevant parameters. The contributions from the diffusioosmotic flow along the tube wall and wall-corrected diffusiophoretic driving force to the particle velocity can be superimposed due to the linearity. Although the diffusiophoretic velocity in an uncharged microtube is in general a decreasing function of the particle-to-tube radius ratio and can reverse its direction, it can increase with increases in this ratio due to the competition of the wall effects of possible electrochemical enhancement and hydrodynamic retardation to the particle motion. When the zeta potentials associated with the tube and particle are equivalent, the diffusioosmotic flow induced by the tube wall dominates the diffusiophoretic motion.

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Electrophoresis of a colloidal sphere with double-layer polarization in a microtube

Cited by 10 publications

References 24 publications

Review of nonlinear electrokinetic flows in insulator‐based dielectrophoresis: From induced charge to Joule heating effects

Review of nonlinear electrokinetic flows in insulator‐based dielectrophoresis: From induced charge to Joule heating effects

Nonlinear Electrophoresis of Highly Charged Nonpolarizable Particles

Diffusiophoresis of a charged particle in a microtube

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