Pair interactions in induced charge electrophoresis of conducting cylinders

Feng, Huicheng; Wong, Teck Neng; Marcos, .

doi:10.1016/j.ijheatmasstransfer.2015.04.063

Cited by 15 publications

(8 citation statements)

References 57 publications

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“…Particles were tested in two different microchannel geometries: one with no posts (Figure a) for performing the E EEC experiments at uniform E 0 and the other with a two-post geometry at the middle section (Figure a, inset), which allowed us to introduce a field nonuniformity to capture particles. The second case admits a representation in the bipolar system of coordinates (Figure S3) in which the Laplace equation is separable . We have derived the analytic expression for this E field within the microchannel by approximating the two-post geometry as two dielectric circles of permittivity ϵ in and diameter D separated by a distance G , immersed in an infinite 2D medium with permittivity ϵ m .…”

Section: Theory and Computational Modelmentioning

confidence: 99%

Direct Current Electrokinetic Particle Trapping in Insulator-Based Microfluidics: Theory and Experiments

et al. 2020

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The classic theory of direct-current (DC) insulator-based dielectrophoresis (iDEP) considers that, in order to elicit particle trapping, dielectrophoretic (DEP) velocity counterbalances electrokinetic (EK) motion, that is, electrophoresis (EP) and electro-osmotic flow (EOF). However, the particle velocity DEP component requires empirical correction factors (sometimes as high as 600) to account for experimental observations, suggesting the need for a refined model. Here, we show that, when applied to particle suspensions, a high-magnitude DC uniform electric field induces nonlinear particle velocities, leading to particle flow reversal beyond a critical field magnitude, referred to as the EK equilibrium condition. We further demonstrate that this particle motion can be described through an exploratory induced-charge EP nonlinear model. The model predictions were validated under an insulator-based microfluidic platform demonstrating predictive particle trapping for three different particle sizes (with an estimation error < 10%, not using correction factors). Our findings suggest that particle motion and trapping in “DC-iDEP” devices are dominated by EP and EOF, rather than by DEP effects.

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Section: Theory and Computational Modelmentioning

confidence: 99%

Direct Current Electrokinetic Particle Trapping in Insulator-Based Microfluidics: Theory and Experiments

et al. 2020

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“…The proposed nanopore diode has a simple two-electrode configuration, which features surface charge profiles that are induced by an externally-applied electric field via electrochemical polarization of the inner surface of a conducting metallic nanochannel. The density of the induced surface charge on the conducting end is linearly proportional to the voltage difference along the nanopore direction according to the theory of induced-charge electrokinetics (ICEK) [45][46][47][48][49][50][51][52][53], and once in combination with a natively-charged dielectric nanopore gives rise to a desired ion-current rectification behavior (Figure 1a-d). Reversal of the rectification polarity occurs once the dielectric nanopore with a negative wall charge (Figure 1a,b) is replaced by one with a positive wall charge (Figure 1c,d).…”

Section: Introductionmentioning

confidence: 99%

A Simulation Analysis of Nanofluidic Ion Current Rectification Using a Metal-Dielectric Janus Nanopore Driven by Induced-Charge Electrokinetic Phenomena

et al. 2020

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We propose herein a unique mechanism of generating tunable surface charges in a metal-dielectric Janus nanopore for the development of nanofluidic ion diode, wherein an uncharged metallic nanochannel is in serial connection with a dielectric nanopore of fixed surface charge. In response to an external electric field supplied by two probes located on both sides of the asymmetric Janus nanopore, the metallic portion of the nanochannel is electrochemically polarized, so that a critical junction is formed between regions with an enriched concentration of positive and negative ions in the bulk electrolyte adjacent to the conducting wall. The combined action of the field-induced bipolar induced double layer and the native unipolar double layer full of cations within the negatively-charged dielectric nanopore leads to a voltage-controllable heterogenous volumetric charge distribution. The electrochemical transport of field-induced counterions along the nanopore length direction creates an internal zone of ion enrichment/depletion, and thereby enhancement/suppression of the resulting electric current inside the Janus nanopore for reverse working status of the nanofluidic ion diode. A mathematical model based upon continuum mechanics is established to study the feasibility of the Janus nanochannel in causing sufficient ion current rectification, and we find that only a good matching between pore diameter and Debye length is able to result in a reliable rectifying functionality for practical applications. This rectification effect is reminiscent of the typical bipolar membrane, but much more flexible on account of the nature of a voltage-based control due to induced-charge electrokinetic polarization of the conducting end, which may hold promise for osmotic energy conversion wherein an electric current appears due to a difference in salt concentration. Our theoretical demonstration of a composite metal-dielectric ion-selective medium provides useful guidelines for construction of flexible on-chip platforms utilizing induced-charge electrokinetic phenomena for a high degree of freedom ion current control.

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“…Induced-charge electro-osmosis (ICEO) has been attracting increasing attention in recent decades owing to its nonlinear relationship with applied electric fields [1][2][3][4]. Various ICEO-based applications have been proposed and developed, ranging from micropumps [5], micromixers [6,7], microvalves [8], and micromotors [9] to trappers of microparticles [10] and microdroplets [11].…”

Section: Introductionmentioning

confidence: 99%

Net fluid flow and non-Newtonian effect in induced-charge electro-osmosis of polyelectrolyte solutions

Feng

Wong

2019

Phys. Rev. E

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Pair interactions in induced charge electrophoresis of conducting cylinders

Cited by 15 publications

References 57 publications

Direct Current Electrokinetic Particle Trapping in Insulator-Based Microfluidics: Theory and Experiments

Direct Current Electrokinetic Particle Trapping in Insulator-Based Microfluidics: Theory and Experiments

A Simulation Analysis of Nanofluidic Ion Current Rectification Using a Metal-Dielectric Janus Nanopore Driven by Induced-Charge Electrokinetic Phenomena

Net fluid flow and non-Newtonian effect in induced-charge electro-osmosis of polyelectrolyte solutions

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