Induced-Charge Electroosmosis Around Touching Metal Rods

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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Induced-charge electro-osmotic flow around cylinders with various orientations

Proceedings of the Institution of Mechanical Engineers Part C Journal of Mechanical Engineering Science ◽

10.1177/0954406216656886 ◽

2016 ◽

Vol 231 (21) ◽

pp. 4057-4066 ◽

Cited By ~ 6

Author(s):

Cetin Canpolat

Keyword(s):

Electric Fields ◽

Double Layers ◽

Cylinder Surface ◽

Osmotic Flow ◽

Ac Electric Fields ◽

Velocity Magnitude ◽

Electro Osmosis ◽

Microparticle Image Velocimetry ◽

Induced Charge ◽

Electro Osmotic Flow

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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Experimental Analysis of Microchannel Entrance Length Characteristics Using Microparticle Image Velocimetry

Journal of Fluids Engineering ◽

10.1115/1.4001292 ◽

2010 ◽

Vol 132 (4) ◽

Cited By ~ 34

Author(s):

Tariq Ahmad ◽

Ibrahim Hassan

Keyword(s):

Reynolds Number ◽

Flow Field ◽

Entrance Region ◽

Working Fluid ◽

Parallel Plates ◽

Entrance Length ◽

Number Range ◽

Micro Piv ◽

Image Velocimetry ◽

Microparticle Image Velocimetry

The study of the entrance region of microchannels and microdevices is limited, yet important, since the effect on the flow field and heat transfer mechanisms is significant. An experimental study has been carried out to explore the laminar hydrodynamic development length in the entrance region of adiabatic square microchannels. Flow field measurements are acquired through the use of microparticle image velocimetry (micro-PIV), a nonintrusive particle tracking and flow observation technique. With the application of micro-PIV, entrance length flow field data are obtained for three different microchannel hydraulic diameters of 500 μm, 200 μm, and 100 μm, all of which have cross-sectional aspect ratios of 1. The working fluid is distilled water, and velocity profile data are acquired over a laminar Reynolds number range from 0.5 to 200. The test-sections were designed as to provide a sharp-edged microchannel inlet from a very large reservoir at least 100 times wider and higher than the microchannel hydraulic diameter. Also, all microchannels have a length-to-diameter ratio of at least 100 to assure fully developed flow at the channel exit. The micro-PIV procedure is validated in the fully developed region with comparison to Navier–Stokes momentum equations. Good agreement was found with comparison to conventional entrance length correlations for ducts or parallel plates, depending on the Reynolds range, and minimal influence of dimensional scaling between the investigated microchannels was observed. New entrance length correlations are proposed, which account for both creeping and high laminar Reynolds number flows. These correlations are unique in predicting the entrance length in microchannels and will aid in the design of future microfluidic devices.

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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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An Experimental Investigation of the Permeability in Porous Chip Formed by Micropost Arrays Based on Microparticle Image Velocimetry and Micromanometer Measurements

Journal of Fluids Engineering ◽

10.1115/1.4034753 ◽

2016 ◽

Vol 139 (2) ◽

Cited By ~ 2

Author(s):

Haoli Wang ◽

Pengwei Wang

Keyword(s):

Cross Section ◽

Particle Image ◽

Brinkman Equation ◽

Two Dimensional ◽

Micro Particle Image Velocimetry ◽

Micro Piv ◽

Image Velocimetry ◽

Measurement Results ◽

Microparticle Image Velocimetry ◽

The Cross

Measurements of velocity and pressure differences for flows in porous chip fabricated with micropost arrays arranged in square pattern were implemented by using micro-particle image velocimetry (micro-PIV) and high precision micromanometer. Based on the measurement results, the permeability was solved by Brinkman equation under the averaged velocities over the cross section, two-dimensional velocities on the center plane of the microchannels, and the averaged velocities on the center plane considering the effect of depth of correlation (DOC), respectively. The experimental results indicate that the nondimensional permeability based on different velocities satisfies the Kozeny–Carman (KC) equation. The Kozeny factor is taken as 40 for the averaged velocity over the cross section and 15 for two kinds of center velocities based on the micropost array of this study, respectively. The permeability calculated by the velocities on the center plane is greater than that by the averaged velocity over the cross section.

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

Physical Review E ◽

10.1103/physreve.94.022609 ◽

2016 ◽

Vol 94 (2) ◽

Cited By ~ 8

Author(s):

Hideyuki Sugioka

Keyword(s):

Electric Fields ◽

Phase Delay ◽

Direct Simulation ◽

Ac Electric Fields ◽

Delay Effects ◽

Electro Osmosis ◽

Induced Charge

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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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