Dielectrophoretic Control of a Droplet at the Interface of Two Liquids in a Three Liquid System

2018 ◽  
Author(s):  
Manoj Lokanathan ◽  
Enakshi Wikramanayake ◽  
Vaibhav Bahadur ◽  
Roger Bonnecaze
Keyword(s):  
Electric Field ◽  
Electric Fields ◽  
Threshold Voltage ◽  
Water Droplet ◽  
Critical Size ◽  
Silicone Oil ◽  
Liquid System ◽  
Interfacial Phenomena ◽  
Immiscible Liquids ◽  
Voltage Dependent

The influence of an electric field on a water droplet resting at the interface of two immiscible liquids is studied experimentally and theoretically. The droplet is initially in a state of equilibrium due to the balance between gravitational, buoyancy and capillary forces. Application of an electric field across the droplet-interface system disturbs the equilibrium. The electrical force increases the immersion angle of the droplet and eventually causes it to ‘sink’ when a critical immersion angle is reached. Experiments are conducted with a deionized water droplet, resting at the interface of silicone oil and sunflower oil. Experiments involve the application of an electric field and image analysis to track the voltage dependent immersion angle. The objective is to determine the threshold voltage at which the droplet sinks. Experiments are complemented by an analytical model that balances gravity, buoyancy, capillary, and dielectrophoretic forces to predict the change in the position of the droplet and the immersion angle. Experiments and analysis were conducted for Bond numbers ranging from 0.1 to 1.7, the latter being the critical size at which a droplet will ‘sink’ due to its weight. The predicted immersion angles and threshold voltage show a good match to the experimental measurements. Overall, this work highlights the utility of electric fields to control interfacial phenomena at the interface of two immiscible liquids.

scholarly journals Can Electric Fields Drive Chemistry for an Aqueous Microdroplet?

2021 ◽  
Author(s):  
Hongxia Hao ◽  
Itai Leven ◽  
Teresa Head-Gordon
Keyword(s):  
Electric Field ◽  
Electric Fields ◽  
Water Droplet ◽  
Reaction Rates ◽  
Surface Reactivity ◽  
Bulk Solution ◽  
Excess Charge ◽  
Electronic Effects ◽  
Rate Acceleration

Abstract Reaction rates of common organic reactions have been reported to increase by one to six orders of magnitude in aqueous microdroplets compared to bulk solution, but the reasons for the rate acceleration are poorly understood. We investigate the role of electric fields at water droplet surfaces that might explain the promotion of unusual reactive chemistry, along with changes in electric field profiles as a function of excess charge to model the electrospray fragmentation process. We find that electric field alignments along free O-H bonds at the surface yield field strength distributions that are ~30 MV/cm larger on average than that found for O-H bonds in the interior of the water droplet, consistent with greater surface reactivity. We emphasize the importance of both nuclear and electronic effects at the surface, and the non-linear coupling of intramolecular solute polarization with intermolecular solvent modes, as a necessary feature for predicting the higher field strengths at water droplet surfaces.

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.

scholarly journals Surfactant-Switched Positive/Negative Electrorheological Effect in Tungsten Oxide Suspensions

Molecules ◽  
2019 ◽  
Vol 24 (18) ◽  
pp. 3348 ◽  
Author(s):  
Alexander V. Agafonov ◽  
Anton S. Kraev ◽  
Tatiana V. Kusova ◽  
Olga L. Evdokimova ◽  
Olga S. Ivanova ◽  
...  
Keyword(s):  
Sodium Dodecyl Sulfate ◽  
Electric Field ◽  
Tungsten Oxide ◽  
Electric Fields ◽  
Silicone Oil ◽  
Sodium Dodecyl ◽  
Electrorheological Effect ◽  
Multiplicative Effect ◽  
Dodecyl Sulfate ◽  
Visualization Experiments

The electrorheological (ER) effect was experimentally observed in dielectric suspensions containing tungsten oxide (WO3) modified with surfactant molecules (sodium dodecyl sulfate (SDS) and dodecylamine (DDA)) in electric fields up to several kilovolts per millimeter. The dielectric properties of WO3 suspensions in silicone oil were analyzed, depending on the frequency of the electric field, in the range from 25 to 106 Hz. Unmodified WO3 suspensions, as well as suspensions modified with sodium dodecyl sulfate, were shown to exhibit a positive electrorheological effect, whereas suspensions modified with dodecylamine demonstrated a negative electrorheological effect. The quantitative characteristics of the negative electrorheological effect in the strain–compression and shear regimes were obtained for the first time. Visualization experiments were performed to see the chain structures formed by WO3 particles modified with sodium dodecyl sulfate, as well as for dynamic electroconvection in electrorheological fluids containing WO3 modified with dodecylamine. The negative electrorheological effect was shown to be associated with the processes of phase separation in the electric field, which led to a multiplicative effect and a strong electroconvection of the suspension at field strengths above 1 kV/mm.

A Novel Procedure for Pyroelectric Energy Harvesting Using Heat Conduction and the Olsen Cycle

2012 ◽  
Author(s):  
Felix Lee ◽  
Ashcon Navid ◽  
Ian McKinley ◽  
Laurent Pilon
Keyword(s):  
Heat Conduction ◽  
Energy Density ◽  
Electric Field ◽  
Electric Fields ◽  
Vinylidene Fluoride ◽  
Silicone Oil ◽  
Waste Heat ◽  
Thermal Contact ◽  
Electrical Energy ◽  
Olsen Cycle

Waste heat can be directly converted into electrical energy by performing the Olsen cycle on pyroelectric materials. The Olsen cycle consists of two isothermal and two iso-electric field processes in the displacement versus electric field diagram. This paper reports, for the first time, a procedure to implement the Olsen cycle by alternatively placing a pyroelectric material in thermal contact with a cold and a hot source. Poly(vinylidene fluoride-trifluroethylene) [P(VDF-TrFE)] copolymer thin films with 60/40 VDF/TrFE mole fraction were used. A maximum energy density of 155 J/L per cycle was achieved at 0.066 Hz between 25 and 110°C and electric fields cycled between 200 and 350 kV/cm. This energy density was larger than that achieved by our previous prototypical device using oscillatory laminar convective heat transfer. However, it was lower than the energy density obtained in previous “dipping experiments” consisting of alternatively dipping the samples in cold and hot silicone oil baths. This was attributed to (1) the lower operating temperatures due to the slow thermal response achieved using heat conduction and (2) the smaller electric field spans imposed which was limited by the smaller dielectric strength of air. However, the proposed procedure can readily be implemented into devices.

Modeling the Effect of External Electric Fields on the Dynamics of a Confined Water Nano-Droplet

2021 ◽  
Vol 67 ◽  
pp. 89-96
Author(s):  
Mahboubeh Kargar ◽  
Amir Lohrasebi
Keyword(s):  
Molecular Dynamics ◽  
Electric Field ◽  
External Electric Field ◽  
Electric Fields ◽  
Water Droplet ◽  
Water Molecules ◽  
Confined Water ◽  
External Electric Fields ◽  
Water Filters ◽  
Dynamics Method

The effects of the application of constant electric fields on the dynamics of a confined water droplet between two different surfaces are investigated, by using a molecular dynamics method. It is found that the water molecules responded to the electric field, which partially depends on the wettability of the different surfaces. The results reveal that the application of external electric fields causes to create extra pressure on the surfaces, which are theoretically justified. The induced pressure could be experienced by multilayer nano-filters, which are used in desalination processes, with the aid of an external electric field, and may reduce the water filters shelf life.

ELECTRORHEOLOGICAL BEHAVIOR OF CHITOSAN DICARBOXYLATE SUSPENSIONS

2002 ◽  
Vol 16 (17n18) ◽  
pp. 2501-2506 ◽  
Author(s):  
UNG-SU CHOI ◽  
YOUNG-GUN KO
Keyword(s):  
Electric Field ◽  
Electric Fields ◽  
Silicone Oil ◽  
Carbon Chain ◽  
Carbon Chain Length ◽  
Polar Group ◽  
Shear Yield Stress ◽  
Shear Rates ◽  
Shear Yield ◽  
Er Fluid

The electrorheological (ER) behavior of chitosan dicarboxylate suspensions in silicone oil was investigated by varying the electric fields, volume fractions of particles, and shear rates, respectively. The chitosan dicarboxylate susepnsions showed a typical ER response caused by the polarizability of an amide polar group and shear yield stress due to the formation of multiple chains upon application of an electric field. Of these, chitosan malonicate suspension represented slightly higher rheological performance than any other suspensions due to dependent upon the carbon chain length. The shear stress for the suspension exhibited a linear dependence on an electric field power of 1.88. On the basis of the results, the newly synthesized chitosan dicarboxylate suspensions were found to be an anhydrous ER fluid.

Electro-wetting of a nanoscale water droplet on a polar solid surface in electric fields

2018 ◽  
Vol 20 (17) ◽  
pp. 11987-11993 ◽  
Author(s):  
Fenhong Song ◽  
Long Ma ◽  
Jing Fan ◽  
Qicheng Chen ◽  
Guangping Lei ◽  
...  
Keyword(s):  
Electric Field ◽  
Electric Fields ◽  
Solid Surface ◽  
Water Droplet ◽  
Water Molecules ◽  
Polar Surface ◽  
Electro Wetting

Water molecules interact with a polar surface in an electric field to realign their point dipoles, which determine the spreading behaviors of the droplets.

Effect of Graphene/TiO2 (001) Interface on Threshold Voltage and Nonlinearity

NANO ◽  
2018 ◽  
Vol 13 (06) ◽  
pp. 1830004 ◽  
Author(s):  
Yuehua Dai ◽  
Shanshan Gong ◽  
Zhisheng Zhong ◽  
Fengyu Gao ◽  
Feifei Wang ◽  
...  
Keyword(s):  
Electric Field ◽  
Electric Fields ◽  
Threshold Voltage ◽  
Density Functional ◽  
Tight Binding ◽  
Resistive Transition ◽  
Design And Optimization ◽  
Interface Barrier ◽  
Iv Curves ◽  
Energy Package

In this work, the threshold voltage ([Formula: see text]) and nonlinearity (NL) of Graphene (Gra)/TiO2/Gra heterojunction were studied. First, the density functional tight binding (DFTB[Formula: see text]) and much more dynamics were used to investigate the IV curves and the resistive switching properties of TiO2 slab and Gra/TiO2/Gra heterojunction. The NL of Gra/TiO2/Gra heterojunction is stronger than that of the TiO2 slab. The [Formula: see text] of the resistive transition of the heterojunction is larger than that of the TiO2 slab. The tunneling probabilities and the Mulliken atomic population at the Gra/TiO2 interface under different electric fields were calculated by the Cambridge sequential total energy package (CASTEP). Results showed that both the parameters evidently increased under a certain numerical electric field. Finally, the movement of atom in the electric field and the change in the chemical bond were simulated by DFTB[Formula: see text] module. The effect of the Gra/TiO2 interface on [Formula: see text] and NL was further illustrated. Postponed [Formula: see text] and improved NL were found at the heterojunction relative to the TiO2 slab due to the presence of the interface barrier. This work provides guidance and reference for design and optimization of TiO2-based selectors.

SYNTHESIS AND ELECTRORHEOLOGY OF MESOPOROUS PARTICLS SUSPENSIONS

2002 ◽  
Vol 16 (17n18) ◽  
pp. 2514-2520 ◽  
Author(s):  
HYOUNG J. CHOI ◽  
MIN S. CHO ◽  
WHA-SEUNG AHN
Keyword(s):  
Electric Field ◽  
Electric Fields ◽  
Silicone Oil ◽  
Linear Viscoelastic ◽  
Static Yield ◽  
Viscosity Enhancement ◽  
Er Fluids ◽  
Elasticity Measurement ◽  
Static Yield Stress ◽  
Mcm 41

Electrorheological (ER) properties of a fluid composed of mesoporous MCM-41 particles suspended in silicone oil under high electric field were investigated. Typical properties of ER fluids such as viscosity enhancement and viscoelasticity under applied electric fields in MCM-41/silicone oil suspensions were observed. In the dynamic and static yield stress measurements, a strain hardening effect was also observed and subsequently confirmed by elasticity measurement as a function of time under a linear viscoelastic condition.

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