Direct simulation of phase delay effects on induced-charge electro-osmosis under large ac electric fields

Induced-charge electro-osmosis around multiple gold-coated stainless steel rods under various AC electric fields is investigated using the techniques of microparticle image velocimetry and numerical simulation. In this study, the results of interactions between induced electric double layers of two identical conductive cylinders on surrounding fluid are presented. The induced-charge electro-osmosis flow around multiple rods in touch and with one cylinder diameter gap reveals quadrupolar flow structures with four vortices. The induced-charge electro-osmotic flow structure and velocity magnitude also depend on the cylinder geometry and orientation. It is seen that four small vortices develop in the close region of cylinder surface for multiple rods with gap, while the other four large vortices are surrounding them. The distributions of vorticity patterns also strongly depend on cylinder orientation in the close region of cylinder surface.

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Dipolophoresis and Travelling-Wave Dipolophoresis of Metal Microparticles

Micromachines ◽

10.3390/mi11030259 ◽

2020 ◽

Vol 11 (3) ◽

pp. 259

Author(s):

Jose Eladio Flores-Mena ◽

Pablo García-Sánchez ◽

Antonio Ramos

Keyword(s):

Electric Fields ◽

Particle Motion ◽

Numerical Solutions ◽

Particle Surface ◽

Travelling Wave ◽

Aqueous Electrolytes ◽

Small Particles ◽

Ac Electric Fields ◽

Induced Charge ◽

Analytical Expressions

We study theoretically and numerically the electrokinetic behavior of metal microparticles immersed in aqueous electrolytes. We consider small particles subjected to non-homogeneous ac electric fields and we describe their motion as arising from the combination of electrical forces (dielectrophoresis) and the electroosmotic flows on the particle surface (induced-charge electrophoresis). The net particle motion is known as dipolophoresis. We also study the particle motion induced by travelling electric fields. We find analytical expressions for the dielectrophoresis and induced-charge electrophoresis of metal spheres and we compare them with numerical solutions. This validates our numerical method, which we also use to study the dipolophoresis of metal cylinders.

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Induced-Charge Electroosmosis Around Touching Metal Rods

Journal of Fluids Engineering ◽

10.1115/1.4023452 ◽

2013 ◽

Vol 135 (2) ◽

Cited By ~ 17

Author(s):

Cetin Canpolat ◽

Mingkan Zhang ◽

William Rosen ◽

Shizhi Qian ◽

Ali Beskok

Keyword(s):

Electric Fields ◽

Radial Distance ◽

Flow Structures ◽

Weakly Nonlinear ◽

Ac Electric Fields ◽

Velocity Magnitude ◽

Micro Piv ◽

Image Velocimetry ◽

Microparticle Image Velocimetry ◽

Induced Charge

Induced-charge electroosmosis (ICEO) around multiple gold-coated stainless steel rods under different ac electric fields is analyzed using microparticle image velocimetry (micro-PIV) and numerical simulations. In the present investigation, the induced electric double layer (EDL) is in weakly nonlinear limit. The ICEO flow around multiple touching rods exhibits geometry dependent quadrupolar flow structures with four vortices. The velocity magnitude is proportional to the square of the electric field. The ICEO flow velocity also depends on the cylinder orientation. The velocity increases with increased radial distance from the rod’s surface, attains a maximum, and then decays to zero. Experimental and numerical velocity distributions have the same trend beyond 0.2 mm of the rod’s surface.

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Multifrequency Induced-Charge Electroosmosis

Micromachines ◽

10.3390/mi10070447 ◽

2019 ◽

Vol 10 (7) ◽

pp. 447 ◽

Cited By ~ 1

Author(s):

Kai Du ◽

Jingni Song ◽

Weiyu Liu ◽

Ye Tao ◽

Yukun Ren

Keyword(s):

Electric Fields ◽

Physical Phenomenon ◽

Electrode Arrays ◽

Fluidic Channel ◽

Particle Tracing ◽

Convective Mixing ◽

Ac Electric Fields ◽

Electroosmotic Pump ◽

Induced Charge ◽

On Chip

We present herein a unique concept of multifrequency induced-charge electroosmosis (MICEO) actuated directly on driving electrode arrays, for highly-efficient simultaneous transport and convective mixing of fluidic samples in microscale ducts. MICEO delicately combines transversal AC electroosmotic vortex flow, and axial traveling-wave electroosmotic pump motion under external dual-Fourier-mode AC electric fields. The synthetic flow field associated with MICEO is mathematically analyzed under thin layer limit, and the particle tracing experiment with a special powering technique validates the effectiveness of this physical phenomenon. Meanwhile, the simulation results with a full-scale 3D computation model demonstrate its robust dual-functionality in inducing fully-automated analyte transport and chaotic stirring in a straight fluidic channel embedding double-sided quarter-phase discrete electrode arrays. Our physical demonstration with multifrequency signal control on nonlinear electroosmosis provides invaluable references for innovative designs of multifunctional on-chip analytical platforms in modern microfluidic systems.

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Non-monotonic dependence of induced-charge electro-osmosis on ion concentration

Colloids and Surfaces A Physicochemical and Engineering Aspects ◽

10.1016/j.colsurfa.2021.126604 ◽

2021 ◽

pp. 126604

Author(s):

Huicheng Feng ◽

Lingqi Zhao ◽

Xin Zhong ◽

Xingfeng Lei ◽

Teck Neng Wong

Keyword(s):

Ion Concentration ◽

Electro Osmosis ◽

Induced Charge

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Fabrication of ZrO 2 /rGO nanocomposites by flash sintering under AC electric fields

Journal of the American Ceramic Society ◽

10.1111/jace.17991 ◽

2021 ◽

Author(s):

Xinghua Su ◽

Mengying Fu ◽

Gai An ◽

Zhihua Jiao ◽

Qiang Tian ◽

...

Keyword(s):

Electric Fields ◽

Ac Electric Fields ◽

Flash Sintering

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Directed Assembly of Janus Particles under High Frequency ac-Electric Fields: Effects of Medium Conductivity and Colloidal Surface Chemistry

Langmuir ◽

10.1021/la302725v ◽

2012 ◽

Vol 28 (37) ◽

pp. 13201-13207 ◽

Cited By ~ 29

Author(s):

Lu Zhang ◽

Yingxi Zhu

Keyword(s):

Surface Chemistry ◽

Electric Fields ◽

High Frequency ◽

Directed Assembly ◽

Janus Particles ◽

Ac Electric Fields ◽

High Frequency Ac ◽

Medium Conductivity

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AC Electrokinetics for Biosensors

Fluids Engineering ◽

10.1115/imece2004-62013 ◽

2004 ◽

Author(s):

M. Sigurdson ◽

C. Meinhart ◽

D. Wang

Keyword(s):

Electric Fields ◽

Dna Hybridization ◽

Fluid Motion ◽

Diffusive Transport ◽

Analyte Concentration ◽

Ac Electrokinetics ◽

Ac Electric Fields ◽

Binding Rate ◽

Electrothermal Flow ◽

Biosensor Device

We develop here tools for speeding up binding in a biosensor device through augmenting diffusive transport, applicable to immunoassays as well as DNA hybridization, and to a variety of formats, from microfluidic to microarray. AC electric fields generate the fluid motion through the well documented but unexploited phenomenon, Electrothermal Flow, where the circulating flow redirects or stirs the fluid, providing more binding opportunities between suspended and wall-immobilized molecules. Numerical simulations predict a factor of up to 8 increase in binding rate for an immunoassay under reasonable conditions. Preliminary experiments show qualitatively higher binding after 15 minutes. In certain applications, dielectrophoretic capture of passing molecules, when combined with electrothermal flow, can increase local analyte concentration and further enhance binding.

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