Chaotic Induced-Charge Electro-Osmosis

Davidson, Scott; Andersen, Mathias B.; Mani, Ali

doi:10.1103/physrevlett.112.128302

Cited by 111 publications

(90 citation statements)

References 26 publications

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“…A number of different mechanisms have been suggested as explanation for this overlimiting current, most of which are probably important for some system configuration or another. The suggested mechanisms include bulk conduction through the extended space-charge region [4,5], current induced membrane discharge [6], water-splitting effects [7,8], electroosmotic instability [9,10], and most recently, electro-hydrodynamic chaos [11,12].…”

Section: Introductionmentioning

confidence: 99%

Concentration polarization, surface currents, and bulk advection in a microchannel

Nielsen

Bruus

2014

Phys. Rev. E

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We present a comprehensive analysis of salt transport and overlimiting currents in a microchannel during concentration polarization. We have carried out full numerical simulations of the coupled Poisson-Nernst-Planck-Stokes problem governing the transport and rationalized the behaviour of the system. A remarkable outcome of the investigations is the discovery of strong couplings between bulk advection and the surface current; without a surface current, bulk advection is strongly suppressed. The numerical simulations are supplemented by analytical models valid in the long channel limit as well as in the limit of negligible surface charge. By including the effects of diffusion and advection in the diffuse part of the electric double layers, we extend a recently published analytical model of overlimiting current due to surface conduction.

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Section: Introductionmentioning

confidence: 99%

Concentration polarization, surface currents, and bulk advection in a microchannel

Nielsen

Bruus

2014

Phys. Rev. E

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“…Second, we do observe a fieldinduced redistribution of ions, Fig.2. However, the velocity reduction factor cp  caused by concentration polarization has been predicted to be only about 5 [17], thus the effect is unlikely to be the sole factor responsible for the smallness of velocities. Among other reasons are surface contamination [23] and roughness [24], interactions with walls [13], confinement-enhanced viscous friction [25] and the assumption of small voltages Metal-dielectric Janus spheres produce dipolar flows and pumping effects, with contributions ~cos , ~sin to the radial and azimuthal components of ICEO velocities, respectively.…”

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confidence: 99%

“…Even for the simple case of a homogeneous metallic sphere, it is unclear why the experimental velocities [10,13] Recent numerical simulations [17] suggest that one of the reasons might be the concentration polarization effect [18][19]. , since it has been reported that pure water yields the highest electrophoretic velocity of Janus particles while addition of salts cause a slow-down [13].…”

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confidence: 99%

Induced-charge electro-osmosis around metal and Janus spheres in water: Patterns of flow and breaking symmetries

et al. 2014

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We establish experimentally the flow patterns of induced-charge electro-osmosis (ICEO) around immobilized metallic spheres in aqueous electrolyte. The AC field modifies local electrolyte concentration and causes quadrupolar flows with inward velocities being smaller than the outward ones. At high fields, the flow becomes irregular, with vortices smaller than the size of the sphere. Janus metallo-dielectric spheres create dipolar flows and pump the fluid from the dielectric toward the metallic part. The experimentally determined far-field flows decay with the distance as r -3 .

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“…41 The thin layer approximation simplifies the theoretical analysis of AC-FFET induced particle concentrating by assuming the liquid bulk electroneutral, since the induced free charge merely exists within a small region at the electrode/liquid interface. [42][43][44][45][46][47] In this work, we extended the previous theoretical analysis in Ref. 48 and computed FIG.…”

Section: Introductionmentioning

confidence: 70%

On utilizing alternating current-flow field effect transistor for flexibly manipulating particles in microfluidics and nanofluidics

et al. 2016

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By imposing a biased gate voltage to a center metal strip, arbitrary symmetry breaking in induced-charge electroosmotic flow occurs on the surface of this planar gate electrode, a phenomenon termed as AC-flow field effect transistor (AC-FFET). In this work, the potential of AC-FFET with a shiftable flow stagnation line to flexibly manipulate micro-nano particle samples in both a static and continuous flow condition is demonstrated via theoretical analysis and experimental validation. The effect of finite Debye length of induced double-layer and applied field frequency on the manipulating flexibility factor for static condition is investigated, which indicates AC-FFET turns out to be more effective for achieving a position-controllable concentrating of target nanoparticle samples in nanofluidics compared to the previous trial in microfluidics. Besides, a continuous microfluidics-based particle concentrator/director is developed to deal with incoming analytes in dynamic condition, which exploits a design of tandem electrode configuration to consecutively flow focus and divert incoming particle samples to a desired downstream branch channel, as prerequisite for a following biochemical analysis. Our physical demonstrations with AC-FFET prove valuable for innovative designs of flexible electrokinetic frameworks, which can be conveniently integrated with other microfluidic or nanofluidic components into a complete lab-on-chip diagnostic platform due to a simple electrode structure. Published by AIP Publishing.

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Chaotic Induced-Charge Electro-Osmosis

Cited by 111 publications

References 26 publications

Concentration polarization, surface currents, and bulk advection in a microchannel

Concentration polarization, surface currents, and bulk advection in a microchannel

Induced-charge electro-osmosis around metal and Janus spheres in water: Patterns of flow and breaking symmetries

On utilizing alternating current-flow field effect transistor for flexibly manipulating particles in microfluidics and nanofluidics

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