Electrolyte-Dependent Aggregation of Colloidal Particles near Electrodes in Oscillatory Electric Fields

Langmuir ◽  
2014 ◽  
Vol 30 (17) ◽  
pp. 4887-4894 ◽  
Author(s):  
Taylor J. Woehl ◽  
Kelley L. Heatley ◽  
Cari S. Dutcher ◽  
Nicholas H. Talken ◽  
William D. Ristenpart
Keyword(s):  
Electric Fields ◽  
Colloidal Particles

Particle Compaction with Alternating Electric Fields: The Effects of Electrode Geometry

1986 ◽  
Vol 73 ◽  
Author(s):  
Alan J. Hurd
Keyword(s):  
Electric Fields ◽  
Colloidal Particles ◽  
Dielectric Material ◽  
Double Layers ◽  
Electrode Geometry ◽  
Dipole Interactions ◽  
Alternating Electric Fields ◽  
Alternating Electric Field ◽  
Dc Bias ◽  
Induced Dipoles

ABSTRACTA technique for inducing ordered, close-packed arrangements of various symmetries among colloidal particles is discussed. An external alternating electric field applied to the colloid induces dipole interactions of variable strength by polarizing either the dielectric material of the particles or their electrostatic double layers. Ordering in various symmetries can be obtained by switching the field rapidly between pairs of electrodes, thereby changing the orientation of the induced dipoles. A small dc bias serves to deposit and compact the aligned particles.

scholarly journals Tunable two-dimensional assembly of colloidal particles in rotating electric fields

2017 ◽  
Vol 7 (1) ◽  
Author(s):  
Egor V. Yakovlev ◽  
Kirill A. Komarov ◽  
Kirill I. Zaytsev ◽  
Nikita P. Kryuchkov ◽  
Kirill I. Koshelev ◽  
...  
Keyword(s):  
Electric Fields ◽  
Colloidal Particles ◽  
Two Dimensional

Polarization and interactions of colloidal particles in ac electric fields

2008 ◽  
Vol 129 (6) ◽  
pp. 064513 ◽  
Author(s):  
Manish Mittal ◽  
Pushkar P. Lele ◽  
Eric W. Kaler ◽  
Eric M. Furst
Keyword(s):  
Electric Fields ◽  
Colloidal Particles ◽  
Ac Electric Fields

Using Shear and DC Electric Fields to Manipulate and Self-Assemble Dielectric Particles on Microchannel Walls

2014 ◽  
Author(s):  
Minami Yoda ◽  
Necmettin Cevheri
Keyword(s):  
Electric Field ◽  
Electric Fields ◽  
Poiseuille Flow ◽  
Lift Force ◽  
Colloidal Particles ◽  
Solid Surfaces ◽  
Electric Field Magnitude ◽  
Field Magnitude ◽  
Combined Flow ◽  
Lift Forces

Manipulating suspended neutrally buoyant colloidal particles of radii a = O(0.1 μm–1 μm) near solid surfaces, or walls, is a key technology in various microfluidics devices. These particles, suspended in an aqueous solution at rest near a solid surface, or wall, are subject to wall-normal “lift” forces described by the DLVO theory of colloid science. The particles experience additional lift forces, however, when suspended in a flowing solution. A fundamental understanding of such lift forces could therefore lead to new methods for the transport and self-assembly of particles near and on solid surfaces. Various studies have reported repulsive electroviscous and hydrodynamic lift forces on colloidal particles in Poiseuille flow (with a constant shear rate γ̇ near the wall) driven by a pressure gradient. A few studies have also observed repulsive dielectrophoretic-like lift forces in electroosmotic (EO) flows driven by electric fields. Recently, evanescent-wave particle tracking has been used to quantify near-wall lift forces on a = 125 nm–245 nm polystyrene (PS) particles suspended in a monovalent electrolyte solution in EO flow, Poiseuille flow, and combined Poiseuille and EO flow through ∼30 μm deep fused-silica channels. In Poiseuille flow, the repulsive lift force appears to be proportional to γ̇, a scaling consistent with hydrodynamic, vs. electroviscous, lift. In combined Poiseuille and EO flow, the lift forces can be repulsive or attractive, depending upon whether the EO flow is in the same or opposite direction as the Poiseuille flow, respectively. The magnitude of the force appears to be proportional to the electric field magnitude. Moreover, the force in combined flow exceeds the sum of the forces observed in EO flow for the same electric field or in Poiseuille flow for the same γ̇. Initial results also imply that this force, when repulsive, scales as γ̇1/2. These results suggest that the lift force in combined flow is fundamentally different from electroviscous, hydrodynamic, or dielectrophoretic-like lift. Moreover, for the case when the EO flow opposes the Poiseuille flow, the particles self-assemble into dense stable periodic streamwise bands with an average width of ∼6 μm and a spacing of 2–4 times the band width when the electric field magnitude exceeds a threshold value. These results are described and reviewed here.

Experimental Investigation on the Electrokinetic Motions of Colloidal Particles at an Interfacial Boundary Between Solid and Liquid

2019 ◽  
Author(s):  
Katsuaki Shirai ◽  
Shoichiro Kaji ◽  
Shigeo Hosokawa ◽  
Tsuyoshi Kawanami ◽  
Shigeki Hirasawa
Keyword(s):  
Heat Transfer ◽  
Experimental Investigation ◽  
Electric Fields ◽  
Spatial Resolution ◽  
Measurement System ◽  
Colloidal Particles ◽  
Solid Wall ◽  
Wall Region ◽  
And Performance ◽  
Solid Liquid

Abstract We investigate electrokinetic behavior of colloidal particles in the vicinity of a solid-liquid interface. Colloidal liquids are expected to be used as thermal transport media for heat transfer applications such as nanofluids and phase change emulsions. They contain submicrometer-sized particles in liquid, and electrokinetic behavior of the solute particles should play an important role in the heat transfer between solid-liquid interfacing boundaries. However, experimental investigation of the behavior remains difficult due to the required spatial resolution beyond diffraction limit. We developed a measurement system based on laser Doppler principle using an interference of evanescent waves generated at total internal reflections of incident lasers at a solid wall. The system was developed for the measurement of velocities of colloidal particles at an interfacing boundary of colloidal liquid and a solid wall. The system has a unique advantage of a high spatial resolution in the direction perpendicular to the boundary due to the short penetration depth of an evanescent wave in the range of a few hundred nanometers. The principle and performance of the measurement system were investigated using a scanning probe in the measurement volume. We experimentally confirmed the validity of the measurement and characterized the uncertainty of velocity measurement. The system was further applied in a series of measurements of alumina particles dispersed in water in a square-shaped cell under induced electric fields. The measured velocities are proportional to the field strengths at different particle concentrations. The linear relationship is consistent with theoretical predictions, which demonstrates the feasibility of the system for the measurement of velocities of colloidal particles in the near wall region.

Self and Directed Colloidal Assembly on Patterned Electrodes

2005 ◽  
Author(s):  
P. Bahukudumbi ◽  
Michael A. Bevan ◽  
Ali Beskok
Keyword(s):  
Electric Fields ◽  
Colloidal Particles ◽  
Colloidal Particle ◽  
Three Dimensional ◽  
Directed Assembly ◽  
Ordered Structures ◽  
Colloidal Assembly ◽  
Electrode Surfaces ◽  
External Electric Fields ◽  
Potential Energy Landscapes

Clustering of colloidal particles near an electrode surface during and after electrophoretic deposition has been reported in the literature [1, 2, 3, 4]. The aggregation of colloidal particles has made the precise assembly of two and three dimensional colloidal crystals possible. In this paper, we demonstrate the use of external electric fields to sensitively tune the interactions between colloidal particles to form ordered structures. The directed assembly of colloidal particles on patterned electrode surfaces is also investigated as a means of building three-dimensional nanostructures. Finally, a new method to map potential energy landscapes of templated substrates using a diffusing colloidal particle as a sensitive local energy probe is described.

Manipulation of Organic and Inorganic Colloidal Particles by Dielectrophoretic Forces

2007 ◽  
Author(s):  
Ramazan Asmatulu ◽  
Dennis Siginer
Keyword(s):  
Liquid Medium ◽  
Electric Fields ◽  
Colloidal Particles ◽  
Dielectrophoretic Force ◽  
Inorganic Particles ◽  
Ac Electric Fields ◽  
The Creation ◽  
Manipulation Process

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.

Using Shear and Direct Current Electric Fields to Manipulate and Self-Assemble Dielectric Particles on Microchannel Walls

2014 ◽  
Vol 5 (3) ◽  
Author(s):  
Necmettin Cevheri ◽  
Minami Yoda
Keyword(s):  
Electric Field ◽  
Electric Fields ◽  
Poiseuille Flow ◽  
Lift Force ◽  
Colloidal Particles ◽  
Solid Surfaces ◽  
Electric Field Magnitude ◽  
Field Magnitude ◽  
Combined Flow ◽  
Lift Forces

Manipulating suspended neutrally buoyant colloidal particles of radii a = O (0.1–1 μm) near solid surfaces, or walls, is a key technology in various microfluidics devices. These particles, suspended in an aqueous solution at rest near a solid surface, or wall, are subject to wall-normal “lift” forces described by the Derjaguin–Landau–Verwey–Overbeek (DLVO) theory of colloid science. The particles experience additional lift forces, however, when suspended in a flowing solution. A fundamental understanding of such lift forces could therefore lead to new methods for the transport and self-assembly of particles near and on solid surfaces. Various studies have reported repulsive electroviscous and hydrodynamic lift forces on colloidal particles in Poiseuille flow (with a constant shear rate γ· near the wall) driven by a pressure gradient. A few studies have also observed repulsive dielectrophoretic-like lift forces in electroosmotic (EO) flows driven by electric fields. Recently, evanescent-wave particle tracking has been used to quantify near-wall lift forces on a = 125–245 nm polystyrene (PS) particles suspended in a monovalent electrolyte solution in EO flow, Poiseuille flow, and combined Poiseuille and EO flow through ∼30 μm deep fused-silica channels. In Poiseuille flow, the repulsive lift force appears to be proportional to γ·, a scaling consistent with hydrodynamic, versus electroviscous, lift. In combined Poiseuille and EO flow, the lift forces can be repulsive or attractive, depending upon whether the EO flow is in the same or opposite direction as the Poiseuille flow, respectively. The magnitude of the force appears to be proportional to the electric field magnitude. Moreover, the force in combined flow exceeds the sum of the forces observed in EO flow for the same electric field and in Poiseuille flow for the same γ·. Initial results also imply that this force, when repulsive, scales as γ·1/2. These results suggest that the lift force in combined flow is fundamentally different from electroviscous, hydrodynamic, or dielectrophoretic-like lift. Moreover, for the case when the EO flow opposes the Poiseuille flow, the particles self-assemble into dense stable periodic streamwise bands with an average width of ∼6 μm and a spacing of 2–4 times the band width when the electric field magnitude exceeds a threshold value. These results are described and reviewed here.

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