Towards New Methodologies for Manipulation of Colloidal Particles in a Miniaturized Fluidic Device: Optoelectrokinetic Manipulation Technique

2013 ◽  
Vol 135 (2) ◽  
Author(s):  
Jae-Sung Kwon ◽  
Steven T. Wereley
Keyword(s):  
Microfluidic Chip ◽  
Colloidal Particles ◽  
Future Prospects ◽  
Simultaneous Application ◽  
Laser Illumination ◽  
Research Fields ◽  
Ac Electric Field ◽  
Fluidic Device ◽  
New Methodologies ◽  
Rapid Electrokinetic Patterning

The rapid electrokinetic patterning (REP) technique developed recently is a hybrid optoelectrokinetic one that manipulates micro- or nanocolloids in a microfluidic chip using the simultaneous application of a uniform ac electric field and laser illumination. Since its invention, the technique has been applied to many research fields with promising potential, but these applications are still in their early stages. In order to effectively complete and leverage the applications, this paper reviews the publications concerning the REP technique and discusses its underlying principles, applications, and future prospects.

Electrothermal Pumping With Thin Film Resistive Heaters

2012 ◽  
Author(s):  
Andrew Work ◽  
Vanessa Velasco ◽  
Stuart J. Williams
Keyword(s):  
Thin Film ◽  
Tin Oxide ◽  
Indium Tin Oxide ◽  
Parallel Plate ◽  
Colloidal Particles ◽  
Infrared Laser ◽  
Electrode Geometry ◽  
Ac Electric Field ◽  
Glass Slides ◽  
Rapid Electrokinetic Patterning

Rapid Electrokinetic Patterning (REP) is a technique used to gather suspended colloidal particles at a planar electrode surface. REP is capable of gathering colloids using very simplistic electrode geometry. Two parallel plate electrodes are used to supply an AC electric field, and an infrared laser is required to heat the surface. Gold and indium tin oxide (ITO) on glass slides have been used as electrode material. Experiments were conducted using ITO coated glass slides, a 980 nm infrared laser, one-micron red fluorescent polystyrene particles, and an aqueous KCl solution. An inverted Nikon Eclipse microscope was used, and video was captured using a PCO Sensicam camera.

scholarly journals Bidirectional rotation control of a carbon fiber in nematic liquid crystal using AC electric field

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Jun-Yong Lee ◽  
Jeong-Seon Yu ◽  
Jong-Hyun Kim
Keyword(s):  
Free Energy ◽  
Liquid Crystal ◽  
Electric Field ◽  
Colloidal Particles ◽  
Colloidal System ◽  
Wide Angle ◽  
Local Minima ◽  
Free Energies ◽  
Rotation Direction ◽  
Ac Electric Field

Abstract Colloidal particles dispersed in nematic liquid crystals are aligned along the orientation that minimizes the elastic free energy. Through applying an electric field to a nematic colloidal system, the orientation of the director can change. Consequently, colloidal particles realign to minimize the total free energy, which is the sum of the elastic and electric free energies. Herein, we demonstrate that if the preferred rotation directions given by the electric and elastic free energies are different during realignment, the rotation direction of the particle can be controlled by how we apply the electric field. When the strength of the electric field gradually increases, the particles rotate in the same direction as the rotation of the director. However, when a sufficiently high electric field is suddenly applied, the particles rotate in the opposite direction. In this study, we analyzed the effect of free energy on the bidirectional rotation behavior of the particles using a theoretical model. This study provides an effective approach to control the rotational behavior of colloidal particles over a wide-angle range between two orientational local minima.

Characterization of interactive force acting on colloidal particles near an electrode in presence of a high-frequency (>10 kHz) AC electric field using particle diffusometry

2021 ◽  
Vol 1 (1) ◽  
Author(s):  
Kshitiz Gupta ◽  
Dong Hoon Lee ◽  
Steven T. Wereley ◽  
Stuart J. Williams
Keyword(s):  
Electric Field ◽  
Electric Fields ◽  
Particle Motion ◽  
Electrode Surface ◽  
High Frequency ◽  
Colloidal Particles ◽  
Low Frequency ◽  
Double Layers ◽  
Average Height ◽  
Ac Electric Field

Colloidal particles like polystyrene beads and metallic micro and nanoparticles are known to assemble in crystal-like structures near an electrode surface under both DC and AC electric fields. Various studies have shown that this self-assembly is governed by a balance between an attractive electrohydrodynamic (EHD) force and an induced dipole-dipole repulsion (Trau et al., 1997). The EHD force originates from electrolyte flow caused by interaction between the electric field and the polarized double layers of both the particles and the electrode surface. The particles are found to either aggregate or repel from each other on application of electric field depending on the mobility of the ions in the electrolyte (Woehl et al., 2014). The particle motion in the electrode plane is studied well under various conditions however, not as many references are available in the literature that discuss the effects of the AC electric field on their out-of-plane motion, especially at high frequencies (>10 kHz). Haughey and Earnshaw (1998), and Fagan et al. (2005) have studied the particle motion perpendicular to the electrode plane and their average height from the electrode mostly in presence of DC or low frequency AC (<1 kHz) electric field. However, these studies do not provide enough insight towards the effects of high frequency (>10 kHz) electric field on the particles’ motion perpendicular to the electrode plane.  

scholarly journals Comprehensive Analysis of Human Cells Motion under an Irrotational AC Electric Field in an Electro-Microfluidic Chip

PLoS ONE ◽  
2014 ◽  
Vol 9 (4) ◽  
pp. e95231 ◽  
Author(s):  
Clarisse Vaillier ◽  
Thibault Honegger ◽  
Frédérique Kermarrec ◽  
Xavier Gidrol ◽  
David Peyrade
Keyword(s):  
Electric Field ◽  
Microfluidic Chip ◽  
Comprehensive Analysis ◽  
Human Cells ◽  
Ac Electric Field

Line Patterning with Microparticles at Different Positions in a Single Device Based on Negative Dielectrophoresis

2013 ◽  
Vol 25 (4) ◽  
pp. 650-656 ◽  
Author(s):  
Tomoyuki Yasukawa ◽  
◽  
Yusuke Yoshida ◽  
Hironobu Hatanaka ◽  
Fumio Mizutani
Keyword(s):  
Electric Field ◽  
Electric Fields ◽  
Indium Tin Oxide ◽  
Strong Electric Field ◽  
Electric Signal ◽  
Electric Field Line ◽  
Peak Voltage ◽  
Ac Electric Field ◽  
Fluidic Device ◽  
Line Patterns

We report on control of line pattern positioning with particles fabricated by negative dielectrophoresis (n-DEP) using the applied intensity and phase of an AC electric field. Line patterns were fabricated in a microfluidic device consisting of upper conductive indium-tin-oxide (ITO) substrates and lower ITOinterdigitated microband array (IDA) electrodes used as the template. A 6-µm-diameter polystyrene particles suspension was introduced into the device between upper ITO and the bottom ITO-IDA substrate. An AC electric signal of a typically 20 peak-to-peak voltage and 1.0 MHz was then applied to upper ITO and bands on lower IDA, resulting in the formation of line patterns with low electric-field gradient regions. AC voltage was applied to bands A and B on lower IDA with the opposite phase and the same frequency and intensity. When the signal identical to band A was applied to upper ITO, particles were aligned above band A because relatively lower electric fields were produced in these regions. In contrast, the application of a signal identical to band B formed line patterns with particles aligned above band B due to the generation of a strong electric field between band A and upper ITO and the disappearance of the strong electric field between band B and upper ITO. The decrease in applied intensity to upper ITO shifted the accumulated position of particles to the center between bands A and B because of the balance of electric fields generated between band A or B and upper ITO. We thus fabricated line patterns with particles at desired positions in the fluidic device.

Optically Induced Rapid Electrokinetic Patterning of Non-Spherical Particles: Study of Colloidal Phase Transition

2010 ◽  
Author(s):  
Raviraj Vijay Thakur ◽  
Steven Wereley
Keyword(s):  
Phase Transition ◽  
Fluid Mechanics ◽  
Electrode Surface ◽  
Colloidal Particles ◽  
Spherical Particles ◽  
Lab On Chip ◽  
Chip Technology ◽  
Sorting Technique ◽  
On Chip ◽  
Rapid Electrokinetic Patterning

Patterning of colloidal particles on surfaces is an application that has evinced wide interest from the fluid mechanics community, due to its possible applicability in a number of engineering situations such as manufacture of photonic crystals[1], bioengineering tissues[2] and lab on chip technology[3], etc. Recently Kumar et al. had proposed the technique of rapid electrokinetic patterning (REP) [4], a hybrid opto-electric manipulation technique that can manipulate and pattern colloidal particles on an electrode surface. REP utilizes optical landscapes to create local gradients in temperature on an electrode substrate. This allows local changes in permittivity and conductivity of the fluid. Colloidal particles can then be dynamically patterned at the illuminated locations of the electrode surface. REP can be used for capturing selective group of particles and thus it serves as a sorting technique too [5].

Multidirectional, Multicomponent Electric Field Driven Assembly of Complex Colloidal Chains

2015 ◽  
Vol 229 (7-8) ◽  
Author(s):  
Bhuvnesh Bharti ◽  
Orlin D. Velev
Keyword(s):  
Electric Field ◽  
Colloidal Particles ◽  
Field Frequency ◽  
Colloidal Assembly ◽  
Ac Electric Field ◽  
Linear Composite ◽  
Particle Size Ratio ◽  
New Strategy ◽  
Efficient Route ◽  
Tunable Morphology

AbstractExternal fields (magnetic and electric) present a simple, robust and efficient route to manipulate and assemble colloidal particles. We report how biparticle dispersions can be assembled into well-defined arrays of tunable morphology using external AC electric field. Binary dispersions of strongly and weakly charged colloidal particles were arranged into linear composite chains via dipole-dipole attraction. The frequency of the applied electric field was the first control parameter for reversibly tuning the biparticle attraction from longitudinal assembly (in the direction of field) to the traverse one (perpendicular to the field). We show that in addition to frequency, spatial limitations play a key role in the assembly process and may assist in the formation of short bidirectional chain-like clusters or characteristic highly structured strings of colloidal triplets. Thus, we control the long-range organization through a combination of particle size ratio, concentration ratio and field frequency. The new strategy to reconfigure the microstructures can find application in better control of the field driven colloidal assembly processes and may be extended to the formation of more complex and precisely arranged particle networks.

scholarly journals One-directional flow of ionic solutions along fine electrodes under an alternating current electric field

2019 ◽  
Vol 6 (2) ◽  
pp. 180657
Author(s):  
Jung Hwal Shin ◽  
Kanghyun Kim ◽  
Hyeonsu Woo ◽  
In Seok Kang ◽  
Hyun-Wook Kang ◽  
...  
Keyword(s):  
Electric Field ◽  
Electric Fields ◽  
Alternating Current ◽  
Ion Concentration ◽  
Flow Rates ◽  
Directional Flow ◽  
Research Fields ◽  
Offset Voltage ◽  
Ac Electric Field ◽  
Dc Electric Field

Electric fields are widely used for controlling liquids in various research fields. To control a liquid, an alternating current (AC) electric field can offer unique advantages over a direct current (DC) electric field, such as fast and programmable flows and reduced side effects, namely the generation of gas bubbles. Here, we demonstrate one-directional flow along carbon nanotube nanowires under an AC electric field, with no additional equipment or frequency matching. This phenomenon has the following characteristics: First, the flow rates of the transported liquid were changed by altering the frequency showing Gaussian behaviour. Second, a particular frequency generated maximum liquid flow. Third, flow rates with an AC electric field (approximately nanolitre per minute) were much faster than those of a DC electric field (approximately picolitre per minute). Fourth, the flow rates could be controlled by changing the applied voltage, frequency, ion concentration of the solution and offset voltage. Our finding of microfluidic control using an AC electric field could provide a new method for controlling liquids in various research fields.

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