Polarization and interactions of colloidal particles in ac electric fields

Recently, manipulation of the micro and nanoscale objects has been of great interest in verity of engineering and scientific areas. Dielectrophoretic force (DEP) induced technique is predominantly used in the manipulation process in a liquid medium. The phenomenon behind DEP involves the creation of electric forces on particles to generate momentum in nonuniform electric fields, usually coming from AC electric fields. In the present study, we will discuss about the effects of DEP for the manipulation of organic and inorganic particles at micro and nanoscale in detail.

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Electric Conductance

Chemistry of Variable Charge Soils ◽

10.1093/oso/9780195097450.003.0011 ◽

1997 ◽

Author(s):

C. B. Li

Keyword(s):

Electric Field ◽

Electric Fields ◽

Colloidal Particles ◽

Free Solution ◽

Soil Particles ◽

Electric Conductance ◽

Variable Charge ◽

Ac Electric Fields ◽

The Difference ◽

Variable Charge Soils

The migration of colloidal soil particles in an applied electric field has been discussed in Chapter 7. Soil particles carrying electric charges invariably adsorb equivalent amounts of ions of the opposite charge. Generally there is a certain amount of free ions present in soil solution. When an electric field is applied to a soil system, a phenomenon known as electric conductance occurs. As in the case for electrolyte solutions, soil particles and various ions interact with one another during their migration, and these interactions can affect the electric conductance of the system. Variable charge soils carry both positive and negative surface charges, and it can be expected that their interactions with various ions would be rather complicated during conductance. On the other hand, this makes the measurement of electric conductance an effective means in elucidating the mechanisms of interactions between variable charge soils and ions. Both direct-current (DC) electric fields and alternating-current (AC) electric fields can induce the migration of charged particles. In the latter case, the migration of these particles should be related to the frequency of the applied AC electric field. Therefore, in this chapter, after describing the principles of electric conductance of ions and colloids and the factors that affect the conductance of a soil, emphasis shall be placed on the interaction between variable charge soils and various ions as reflected by the frequency effect in electric conductance. For a colloidal suspension, the electric conductance may be regarded as the contribution of conductances of both charged colloidal particles and ions. These two parts may be called the electric conductance of colloidal panicles and the electric conductance of ions, respectively. However, in actual cases it is difficult to distinguish between these two parts. Therefore, it is a general practice to distinguish the electric conductance as that caused by colloidal particles plus their counterions from that caused by ions of the free solution. These may be called electric conductance of the colloid and electric conductance of the free solution. The former conductance is the difference between the electric conductance of the suspension and that of the free solution.

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Field-induced dipolar attraction between like-charged colloids

Soft Matter ◽

10.1039/c8sm00395e ◽

2018 ◽

Vol 14 (22) ◽

pp. 4520-4529 ◽

Cited By ~ 4

Author(s):

Chunyu Shih ◽

John J. Molina ◽

Ryoichi Yamamoto

Keyword(s):

Numerical Simulations ◽

Electric Fields ◽

Double Layer ◽

Electric Double Layer ◽

Colloidal Particles ◽

Direct Numerical Simulations ◽

Ac Electric Fields ◽

Charged Colloids ◽

Anisotropic Interactions

The field induced anisotropic interactions between like-charged colloidal particles is studied using direct numerical simulations, where the polarization of the electric double layer is explicitly computed under external AC electric fields.

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Anisotropic Colloidal Interactions & Assembly in AC Electric Fields

Soft Matter ◽

10.1039/d1sm01227d ◽

2021 ◽

Author(s):

Rachel S. Hendley ◽

Isaac Torres-Diaz ◽

Michael A. Bevan

Keyword(s):

Electric Fields ◽

High Frequency ◽

Colloidal Particles ◽

Dipole Field ◽

Colloidal Interactions ◽

Ac Electric Fields ◽

Dipole Interactions ◽

High Frequency Ac

We match experimental and simulated configurations of anisotropic epoxy colloidal particles in high frequency AC electric fields by identifying analytical potentials for dipole-field and dipole-dipole interactions. We report an inverse...

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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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