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

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.

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Directed Assembly of Nanoelements Using Electrostatically Addressable Templates

MRS Proceedings ◽

10.1557/proc-0901-ra04-01 ◽

2005 ◽

Vol 901 ◽

Cited By ~ 7

Author(s):

Xugang Xiong ◽

Prashanth Makaram ◽

Kaveh Bakhtari ◽

Sivasubramanian Somu ◽

Ahmed Busnaina ◽

...

Keyword(s):

Carbon Nanotubes ◽

Electric Field ◽

Electric Fields ◽

Directed Assembly ◽

Single Wall Carbon Nanotubes ◽

Nanoparticle Assembly ◽

Single Wall Carbon ◽

Ac Electric Fields ◽

Ac Electric Field ◽

Dc Electric Field

AbstractDirected assembly of nanoparticles and single wall carbon nanotubes (SWNTs) using electrostatically addressable templates has been demonstrated. Nanoparticles down to 50 nm are assembled on the Au micro and nanowires of the templates in a DC and AC electric fields. The nanoparticles can be assembled in monolayers and thicker layers. Single wall carbon nanotubes (SWNTs) are also assembled without alignment on Au wires using the nanotemplate. As the size of the template wires is reduced to nanoscale dimensions, an AC electric field proves to be more effective for nanoparticle assembly than a DC electric field.

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Electric Trapping and Lysing of Cells in a Microchannel Constriction

Volume 12: Micro and Nano Systems, Parts A and B ◽

10.1115/imece2009-11903 ◽

2009 ◽

Author(s):

Christopher Church ◽

Junjie Zhu ◽

Guohui George Huang ◽

Gaoyan Wang ◽

Tzuen-Rong Jeremy Tzeng ◽

...

Keyword(s):

Electric Field ◽

Electric Fields ◽

Cell Concentration ◽

Ac Electric Fields ◽

Ac Electric Field ◽

Electrical Lysis ◽

Smooth Switching ◽

Dc Component ◽

High Electric Fields ◽

Pressure Driven Flow

Cell lysis is a necessary step in the analysis of intracellular contents. It has been recently demonstrated in microfluidic devices using four methods: chemical lysis, mechanical lysis, thermal lysis, and electrical lysis [1]. The locally high electric fields needed for electrical lysis have been achieved using micro-electrodes and micro-constrictions for pulsed and continuous DC electric fields, respectively. However, since the two determining factors of electrical lysis are field strength and exposure time, opposing pressure-driven flow must often be used in pure DC lysis to reduce the velocity of the cells and to ensure the cells spend sufficient time in the high electric field region [1,2]. Using DC-biased AC fields can easily fulfill these requirements as only the DC component contributes to cell electrokinetic transport. Prior to lysis, cell concentration can be increased by trapping using dielectrophoresis (DEP), which may occur with either DC or DC-biased AC electric fields [3,4]. This operation is useful in cases where the cell supply is limited or when the cell concentration is too low in general. In this work, red blood cells are used to demonstrate the smooth switching between electrical lysing and trapping in a microchannel constriction. The transition between lysis and trapping is realized by tuning the DC component in a DC-biased AC electric field.

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UNDERSTANDING ELECTRIC INTERACTIONS IN SUSPENSIONS IN GRADIENT AC ELECTRIC FIELDS II: SIMULATIONS AND APPLICATION EXPLORATION

International Journal of Modern Physics B ◽

10.1142/s0217979211058493 ◽

2011 ◽

Vol 25 (07) ◽

pp. 927-933

Author(s):

SHIGERU TADA ◽

YAN SHEN ◽

DAVID JACQMIN ◽

BINGMEI FU ◽

ZHIYONG QIU

Keyword(s):

Electric Field ◽

Electric Fields ◽

Particle Concentration ◽

Corn Oil ◽

Critical Concentration ◽

Md Simulations ◽

Continuous Model ◽

Dynamics Model ◽

Ac Electric Fields ◽

Ac Electric Field

We used numerical simulations of a continuous model and the molecular dynamics model to understand the particle instability, formation of island-like structures and existence of one critical particle concentration of 1% (v/v) for formation of island-like structures in the suspension in a gradient AC electric field reported in Paper I. The simulations of the continuous model show that the critical concentration of 1% (v/v) is the concentration of which the particles of a suspension are just fully filling the lower field region finally. According to the MD simulations, the particles instability does exist in the corn oil in a gradient AC electric field, anisotropic polarization interactions among the particles are responsible for the particle instability and have memory, and the memory is still kept even when the particles are transported by a dielectrophoresis force. The island-like structures can be regarded as signature of the memory. We explored possibilities to apply our findings in biomedical fields.

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Improvement of Interfacial Shear Strength of Mendong Fiber (Fimbristylis globulosa) Reinforced Epoxy Composite Using the AC Electric Fields

International Journal of Polymer Science ◽

10.1155/2015/542376 ◽

2015 ◽

Vol 2015 ◽

pp. 1-10 ◽

Cited By ~ 7

Author(s):

Heru Suryanto ◽

Eko Marsyahyo ◽

Yudy Surya Irawan ◽

Rudy Soenoko ◽

Aminudin

Keyword(s):

Shear Strength ◽

Electric Field ◽

Electric Fields ◽

Interfacial Shear Strength ◽

Interfacial Shear ◽

Epoxy Composites ◽

Polymerization Process ◽

Fiber Reinforced ◽

Ac Electric Fields ◽

Ac Electric Field

The effects of the AC electric field treatment on the interfacial shear strength of mendong fiber-reinforced epoxy composites were investigated. For this purpose, the epoxy (DGEBA) with a cycloaliphatic amine curing agent was treated by the AC electric field during the curing process. The heat generated during the epoxy polymerization process was monitored. Structure of the epoxy was studied by X-ray diffraction, Fourier transform infrared spectroscopy (FTIR), and Scanning Electron Microscope, respectively. The interfacial shear strength (IFSS) was also measured using a single fiber pull-out test. XRD analyzes indicated that the treatment of AC electric fields was able to form a crystalline phase of epoxy. IFSS of the mendong fiber-reinforced epoxy composites was optimum increased by 38% in the AC electric fields treatment of 750 V/cm.

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Effect of Microstructure on Lifetime Performance of Barium Titanate Ceramics Under DC and AC Electric Fields

ASME 2010 Conference on Smart Materials, Adaptive Structures and Intelligent Systems, Volume 1 ◽

10.1115/smasis2010-3722 ◽

2010 ◽

Author(s):

Jay Shieh

Keyword(s):

Fatigue Strength ◽

Barium Titanate ◽

Electric Field ◽

Electric Fields ◽

Time To Failure ◽

Electrical Loading ◽

Ac Electric Fields ◽

Lifetime Performance ◽

Weibull Statistical Analysis ◽

Dc Electric Field

Bulk barium titanate (BaTiO3 ) ceramic specimens with bimodal microstructures are prepared and their dielectric and fatigue strengths are investigated under an alternating current (AC) electric field and a direct current (DC) electric field. It is found that under AC electrical loading, both the dielectric and fatigue strengths decrease with increasing amount of coarse abnormal grains. The scatter of the AC fatigue strength is characterized with the Weibull statistics. The extent of scatter of the AC fatigue strength data correlates strongly with the size distribution of the coarse grains. Such correlation is resulted from the presence of intrinsic defects within the microstructure. For DC electrical loading, the time to failure of the specimens with coarse abnormal grains is significantly shorter than the lifetimes of the specimens with only small normal grains. It is found that under a DC electric field of 6 MVm−1, the BaTiO3 specimens would fail within 200 h when abnormal grains are present in the microstructure. However, the lifetimes of the specimens containing abnormal grains vary significantly from one to another. The Weibull statistical analysis indicates that the amount of abnormal grains has little influence on the lifetime performance of bulk BaTiO3 ceramics under large DC electric fields. In most of the failed BaTiO3 specimens under DC electrical loading, regardless of their lifetimes, large through-thickness round holes with recrystallization features are present. A mixed failure mode consisting of avalanche and thermal breakdowns is proposed for the failed specimens.

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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

14th International Symposium on Particle Image Velocimetry ◽

10.18409/ispiv.v1i1.56 ◽

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.

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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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Dynamic Electromechanical Response of Multilayered Piezoelectric Composites From Room to Cryogenic Temperatures for Fuel Injector Applications

Journal of Engineering Materials and Technology ◽

10.1115/1.4006504 ◽

2012 ◽

Vol 134 (3) ◽

Cited By ~ 8

Author(s):

Yasuhide Shindo ◽

Takayoshi Sasakura ◽

Fumio Narita

Keyword(s):

Domain Wall ◽

Electric Field ◽

Electric Fields ◽

Wall Motion ◽

Domain Wall Motion ◽

Cryogenic Temperatures ◽

Fuel Injector ◽

Temperature Dependent ◽

Piezoelectric Composites ◽

Ac Electric Fields

This paper studies the dynamic electromechanical response of multilayered piezoelectric composites under ac electric fields from room to cryogenic temperatures for fuel injector applications. A shift in the morphotropic phase boundary (MPB) between the tetragonal and rhombohedral/monoclinic phases with decreasing temperature was determined using a thermodynamic model, and the temperature dependent piezoelectric coefficients were obtained. Temperature dependent coercive electric field was also predicted based on the domain wall energy. A phenomenological model of domain wall motion was then used in a finite element computation, and the nonlinear electromechanical fields of the multilayered piezoelectric composites from room to cryogenic temperatures, due to the domain wall motion and shift in the MPB, were calculated. In addition, experimental results on the ac electric field induced strain were presented to validate the predictions.

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