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.

The elongated shape of a dielectric drop deformed by a strong electric field

2010 ◽  
Vol 664 ◽  
pp. 286-296 ◽  
Author(s):  
DOV RHODES ◽  
EHUD YARIV
Keyword(s):  
Electric Field ◽  
Electric Fields ◽  
Strong Electric Field ◽  
Outer Region ◽  
Spherical Shape ◽  
Problem Formulation ◽  
Boundary Integral ◽  
Uniform Electric Field ◽  
Cross Sectional ◽  
Drop Shape

A dielectric drop is suspended within a dielectric liquid and is exposed to a uniform electric field. Due to polarization forces, the drop deforms from its initial spherical shape, becoming prolate in the field direction. At strong electric fields, the drop elongates significantly, becoming long and slender. For moderate ratios of the permittivities of the drop and surrounding liquid, the drop ends remain rounded. The slender limit was originally analysed by Sherwood (J. Phys. A, vol. 24, 1991, p. 4047) using a singularity representation of the electric field. Here, we revisit it using matched asymptotic expansions. The electric field within the drop is continued into a comparable solution in the ‘inner’ region, at the drop cross-sectional scale, which is itself matched into the singularity representation in the ‘outer’ region, at the drop longitudinal scale. The expansion parameter of the problem is the elongated drop slenderness. In contrast to familiar slender-body analysis, this parameter is not provided by the problem formulation, and must be found throughout the course of the solution. The drop aspect-ratio scaling, with the 6/7-power of the electric field, is identical to that found by Sherwood (J. Phys. A, vol. 24, 1991, p. 4047). The predicted drop shape is compared with the boundary-integral solutions of Sherwood (J. Fluid Mech., vol. 188, 1988, p. 133). While the agreement is better than that found by Sherwood (J. Phys. A, vol. 24, 1991, p. 4047), the weak logarithmic decay of the error terms still hinders an accurate calculation. We obtain the leading-order correction to the drop shape, improving the asymptotic approximation.

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 IS QFT WITH EXTERNAL BACKGROUNDS A CONSISTENT MODEL?

2011 ◽  
Vol 03 ◽  
pp. 58-64
Author(s):  
S. P. GAVRILOV ◽  
D. M. GITMAN
Keyword(s):  
Dirac Equation ◽  
Electric Field ◽  
Electric Fields ◽  
Strong Electric Field ◽  
Coulomb Field ◽  
Back Reaction ◽  
Consistent Model

We discuss consistency of the concept of external background in QFT. Different restrictions on magnitude of magnetic and electric fields are analyzed. The back reaction due to strong electric field is calculated and restrictions on the magnitude and duration of such a field are obtained. The problem of consistency of Dirac equation with a superstrong Coulomb field is discussed.

UNDERSTANDING ELECTRIC INTERACTIONS IN SUSPENSIONS IN GRADIENT AC ELECTRIC FIELDS I: EXPERIMENTAL

2011 ◽  
Vol 25 (07) ◽  
pp. 919-925
Author(s):  
YAN SHEN ◽  
ZHIYONG QIU ◽  
SHIGERU TADA
Keyword(s):  
Electric Field ◽  
Electric Fields ◽  
Corn Oil ◽  
Electrode Array ◽  
Ac Electric Fields ◽  
Ac Electric Field ◽  
Alpha Olefin ◽  
Dilute Suspensions ◽  
Spatially Periodic ◽  
Neutrally Buoyant

When neutrally buoyant poly alpha olefin particles in corn oil were exposed to a gradient ac electric field generated by a spatially periodic electrode array, these particles experienced the negative dielectrophoresis and instability in all the suspensions of concentration range from 0.01% to 5% (v/v). One critical particle concentration was experimentally determined as 1% (v/v) below which the particles in corn oil were segregated to form island-like structures in the lower electric field regions; and above which, particles only formed straight stripes. The island-like structure was suspended in the lowest electric field area. Specially designed experiments with a suspension of 1.126% (v/v) confirmed that there exists particle instability. Anisotropic properties of electric interactions are responsible for particle instability in all the suspensions of different concentrations and island-like structures were formed only in the dilute suspensions in which the particle instability has enough space to be developed.

Precise morphology control and fast merging of a complex multi-emulsion system: the effects of AC electric fields

Soft Matter ◽  
2019 ◽  
Vol 15 (28) ◽  
pp. 5614-5625 ◽  
Author(s):  
Yi Huang ◽  
Shuai Yin ◽  
Wen Han Chong ◽  
Teck Neng Wong ◽  
Kim Tiow Ooi
Keyword(s):  
Electric Field ◽  
Electric Fields ◽  
Morphology Control ◽  
Emulsion System ◽  
Contact Type ◽  
Ac Electric Fields ◽  
Ac Electric Field

We showed a full morphology control over complex emulsions through an AC electric field by non-contact type of electrodes.

Comparison of Cable Insulation Control in Weak and Strong Electric Fields

2015 ◽  
Vol 756 ◽  
pp. 486-490 ◽  
Author(s):  
Nadezda S. Starikova ◽  
Vitaly V. Redko ◽  
G.V. Vavilova
Keyword(s):  
Electric Field ◽  
Electric Fields ◽  
Strong Electric Field ◽  
Weak Electric Field ◽  
Cable Insulation ◽  
Modern Methods ◽  
Insulation Thickness ◽  
Defect Dimension ◽  
Cylindrical Capacitor ◽  
Strong Electric Fields

In this paper the modern methods of cable products insulation control are referred. A comparison of efficiency of the cable insulation defects control by changing in cable area capacitance is carried out in the strong and weak electric fields. The electric cable can be represented as a cylindrical capacitor, but to simplify the issue the insulation area is represented as a plate capacitor with anisotropic dielectric. The cable insulation model is created in the software Comsol Multyphysic. The effect of the defect dimension on the cable area electric capacitance in a strong and weak electric field is described. Also, the control sensitivity of both methods was assessed and compared with each other. The control sensitivity in a weak electric field is slightly higher for the defects with small size (less than 70% from insulation thickness). The control sensitivity in a strong electric field is considerably higher for the defects with big size (more than 70% from insulation thickness).

An Experimental Investigation on Polypyrrole Films Electro-Polymerized under a High Transverse Electric Field

2013 ◽  
Vol 343 ◽  
pp. 77-83
Author(s):  
D.M.G. Preethichandra
Keyword(s):  
Electric Field ◽  
Electric Fields ◽  
Transverse Electric ◽  
Transverse Field ◽  
Transverse Electric Field ◽  
Peak Voltage ◽  
Cross Sectional ◽  
Polypyrrole Films ◽  
Transverse Electric Fields ◽  
Microscopic Investigations

Polypyrrole films were electrodeposited under different high transverse electric fields, and their film morphologies and functionalities were investigated. The surface morphology at the initial polymerization stage was investigated under AFM and the cross sectional morphologies of fully grown films were investigated by SEM. Both these microscopic investigations revealed the film morphology has been influenced by the applied transverse field. The cyclic voltammetry tests illustrate a reduction in the anodic peak voltage with the increase of transverse field. All these results suggest that the polymer electro-polymerized under a transverse high transverse electric field has some degree of pre-orientation compared to the films synthesized without a transverse electric field.

Pool-Frenkel effect and high frequency dielectric constant determination of semiconducting P2O5-Li2MoO4-Li2O and P2O5-Na2MoO4-Na2O bulk glasses

Open Physics ◽  
2008 ◽  
Vol 6 (2) ◽  
Author(s):  
Dariush Souri ◽  
Mohammad Elahi ◽  
Mohammad Yazdanpanah
Keyword(s):  
Dielectric Constant ◽  
Electric Field ◽  
Electric Fields ◽  
Threshold Voltage ◽  
High Frequency ◽  
Strong Electric Field ◽  
Nonlinear Effects ◽  
High Frequency Dielectric Constant ◽  
Conduction State ◽  
Current Voltage

AbstractThe ternary 70P2O5-10Li2MoO4-20Li2O and 70P2O5-10Na2MoO4-20Na2O glasses, prepared by the press-melt quenching technique, were studied at temperatures between 298 and 418 K for their high dc electric field properties. For the above purpose, the effect of a strong electric field on the dc conduction of these amorphous bulk samples was investigated using the gap-type electrode configuration. At low electric fields, the current-voltage (I — V) characteristics have a linear shape, while at high electric fields (> 103 V/cm), bulk samples show nonlinear effects (nonohmic conduction). Current-voltage curves show increasing departure from Ohm’s law with increasing current density, leading to critical phenomena at a maximum voltage (threshold voltage), known as switching (switch from a low-conduction state to a higher-conduction state at threshold voltage). The Pool-Frenkel high-field effect was observed at electrical fields of about 103–104 V/cm; then the lowering factor of the potential barrier, the high frequency dielectric constant, and the refractive index of these glasses were determined.

Magnitude of Intrinsic Electrocaloric Effect in Pb(Zr1-xTix)O3 at High Electric Fields

2013 ◽  
Vol 700 ◽  
pp. 7-10
Author(s):  
Wen Jiang Feng ◽  
Zhi Guo Zhang ◽  
Chuang Wu ◽  
Hao Chen
Keyword(s):  
Electric Field ◽  
Electric Fields ◽  
Structural Transition ◽  
Strong Electric Field ◽  
Zero Field ◽  
Electrocaloric Effect ◽  
Structure Transition ◽  
First Order ◽  
High Electric Fields ◽  
Curie Temperatures

The structure transition and electrocaloric effect in PbZr1-xTixO3withx=0.5 and 0.6 were MV/m can make the structural transition be a continuous one. In addition, whenx=0.5 and 0.6 at the zero field, the first order structural transition occurs atT0=665 and 691 K, respectively. The first order structural transition comes to the second one upon the strong electric field, which leads to lower the change of specific hea. The structural transition temperature is shifted at high temperature with increasing electric field. The maximum electrocaloric effect is present at about 200 K above their corresponding Curie temperatures.

Effects of AC/DC Electric Fields on Stretching DNA Molecules

NANO ◽  
2020 ◽  
Vol 15 (05) ◽  
pp. 2050065
Author(s):  
Ying Wang ◽  
Mingyan Gao ◽  
Yingmin Qu ◽  
Jun Hu ◽  
Ying Xie ◽  
...  
Keyword(s):  
Electric Field ◽  
Electric Fields ◽  
Dna Molecules ◽  
Dna Interactions ◽  
Biophysical Properties ◽  
Voltage Range ◽  
Atomic Force ◽  
Ac Electric Field ◽  
Dc Electric Field ◽  
Dc Electric Fields

The effects of AC/DC electric fields on stretching DNA molecules were discussed in this work. In the experiments of stretching DNA molecules with AC/DC electric fields, the voltage range was changed from 0[Formula: see text]V to 10[Formula: see text]V, and the frequency of AC electric field was kept at 50[Formula: see text]kHz. An atomic force microscope (AFM) was used to obtain DNA distributions under different electric fields. DNA molecules were curved and randomly distributed in solution if there was not any force applied to them. When an AC electric field was applied to the DNA sample, the curvature of DNA molecules was decreased gradually, and the stretching result was more obvious with the increase of voltage from 0.1[Formula: see text]V to 5[Formula: see text]V. The DNA molecules were broken when the voltage was increased to 6[Formula: see text]V. However, under the DC electric field, the stretching result of DNA molecules reached to their optimum state when the voltage was 2[Formula: see text]V, and they kept their steady state even though larger electric field intensities applied to the electrodes. The results can be used for the study of DNA–DNA, protein–DNA and quantum dot–DNA interactions and for the exploration of DNA biophysical properties.

Sign in / Sign up

Export Citation Format

Share Document