Rhythmic motion of a droplet under a dc electric field

We investigate the motion of electrically charged metallic nano-and microparticles produced by laser ablation in He gas and injected into superfluid helium. In the presence of a vertical static electric field, the particles either perform a repetitive shuttle-like motion transporting the charge across the liquid-gas interface or become trapped under the free surface of liquid He and coalesce into long filaments and complex two-dimensional mesoscopic networks. A classical electrohydrodynamic model is used to describe the motion of charged microparticles in superfluid He. The resulting filaments and networks are analyzed using electron microscopy. It is demonstrated that each filament is in fact composed of a large number of nanowires with a characteristic diameter of order of 10 nm and extremely large aspect ratios.

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“…[23][24][25][26][27] The phenomenon is referred to as a contact charge electrophoresis 27,28 or a charge-shuttling 23 …”

Section: View Article Onlinementioning

confidence: 99%

Metallic nanowires and mesoscopic networks on a free surface of superfluid helium and charge-shuttling across the liquid–gas interface

Moroshkin

Batulin

Leiderer

et al. 2016

Phys. Chem. Chem. Phys.

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“…[20][21][22][23][24][25][26] Jung et al 24 and Im et al 20,22 studied the oscillatory migration of charged water droplets between two parallel electrodes. Oscillatory motion was also recorded for falling water droplets between parallelplated electrodes.…”

Section: Introductionmentioning

confidence: 99%

Oscillatory motion of water droplets in kerosene above co-planar electrodes in microfluidic chips

et al. 2014

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We experimentally observed oscillatory motion of water droplets in microfluidic systems with coplanar microelectrodes under imposed DC electric fields. Two-electrode arrangement with no bipolar electrode and eight-electrode arrangement with six bipolar microelectrodes were investigated. Kerosene was used as the continuous phase. We studied the dependences of the oscillation frequency on the electric field intensity and ionic strength of the water phase. We found that the electric field dependence is strongly nonlinear and discussed possible reasons of this phenomenon, e.g., the droplet deformation at electrode edges that affects the charge transfer between the electrode and droplet or the interplay between the Coulomb force on free charge and the dielectrophoretic force. Our experiments further revealed that the oscillation frequency decreases with growing salt concentration in the two-electrode arrangement, but increases in the eight-electrode arrangement, which was attributed to surface tension related processes and electrochemical processes on the bipolar electrodes. Finally, we analyzed the effects of the electric field on the oscillatory motion by means of a simplified mathematical model. It was shown that the electric force imposed on the droplet charge is the key factor to induce the oscillations and the dielectrophoretic force significantly contributes to the momentum transfer at the electrode edges. For the same electric field strength, the model is able to predict the same oscillation frequency as that observed in the experiments.

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“…For example, for a droplet radius ratio (R core /R shell ) of 0.40, the initial velocity is typically of the order of 10 -3 ms -1 , whereas the velocity after first contact is typically of the order of 10 -2 ms -1 . This general behaviour of an initial charge followed by active charging has been observed by other groups (Bailes et al, 2000;Hase et al, 2006;Im et al, 2012;Im et al, 2011a;Jalaal et al, 2010;Jung et al, 2008), although so far no other group has attempted experiments with complex-multiple droplets. As the core-shell droplet was detached from the microcapillary the inner oil droplet was horizontally centred inside the water shell (Fig.…”

Section: General Behaviour Of (O/w)/o Dropletsmentioning

confidence: 60%

Electrophoretic manipulation of multiple-emulsion droplets

Schoeler

Josephides

Chaurasia

et al. 2014

Applied Physics Letters

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In this report the electrophoretic manipulation of structured oil-water-oil (O/W)/O core-shell droplets is presented. Water shells have been created that allow the electrophoretic manipulation of oil droplets in an oil environment. It was found that the inner droplet regardless of size and composition does not affect the electrophoretic mobility of the outer water shell, neither before nor after contact with a biased electrode. This method can be used for the manipulation of oil droplets in a continuous oil phase or for the transportation of microbial cells that would otherwise be killed at low electric field strengths.

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Rhythmic motion of a droplet under a dc electric field

Cited by 85 publications

References 10 publications

Metallic nanowires and mesoscopic networks on a free surface of superfluid helium and charge-shuttling across the liquid–gas interface

Metallic nanowires and mesoscopic networks on a free surface of superfluid helium and charge-shuttling across the liquid–gas interface

Oscillatory motion of water droplets in kerosene above co-planar electrodes in microfluidic chips

Electrophoretic manipulation of multiple-emulsion droplets

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