Drop formation via breakup of a liquid bridge in an AC electric field

Lee, Beom Seok; Cho, Hye-Jung; Lee, Jeong-Gun; Huh, Nam; Choi, Jeong‐Woo; Kang, In Seok

doi:10.1016/j.jcis.2006.05.060

Cited by 29 publications

(9 citation statements)

References 19 publications

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“…For these instabilities, liquid inertia plays a key role, whereas for instabilities in thin films, liquid inertia is usually neglected. We also note that the use of AC fields to destabilize fluid jets has been studied both theoretically (González et al 1989;González, Ramos & Castellanos 1997González, Garcia & Castellanos 2003) and experimentally (Sato 1984;Yeo et al 2004;Lee et al 2006a), and it has been found that AC fields may be used to create smaller droplets, which is of interest for ink-jet printing. However, no studies have looked at how AC fields may be used to control thin-film pattern formation.…”

Section: Introductionmentioning

confidence: 93%

AC electrohydrodynamic instabilities in thin liquid films

Roberts

Kumar

2009

J. Fluid Mech.

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When DC electric fields are applied to a thin liquid film, the interface may become unstable and form a series of pillars. In this paper, we apply lubrication theory to examine the possibility of using AC electric fields to exert further control over the size and shape of the pillars. For perfect dielectric films, linear stability analysis shows that the influence of an AC field can be understood by considering an effective DC field. For leaky dielectric films, Floquet theory is applied to carry out the linear stability analysis, and it reveals that high frequencies may be used to inhibit the accumulation of interfacial free charge, leading to a lowering of growth rates and wavenumbers. Nonlinear simulations confirm the results of the linear stability analysis while also uncovering additional mechanisms for tuning overall pillar height and width. The results presented here may be of interest for the controlled creation of surface topographical features in applications such as patterned coatings and microelectronics.

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Section: Introductionmentioning

confidence: 93%

AC electrohydrodynamic instabilities in thin liquid films

Roberts

Kumar

2009

J. Fluid Mech.

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“…This method is good in the spot topology and the robustness. AC or DC electric field is exerted to a pendant droplet at a nozzle tip, then a liquid bridge is formed and its break‐up occurs to leave a daughter droplet on the substrate 18–20. As a modification of the original EHD method, Lee 21 suggested a way of dispensing picoliter droplets using the phenomenon of electric charge concentration (ECC) near the tip of the droplet when the counter electrode is not used.…”

Section: Introductionmentioning

confidence: 99%

Pumpless dispensing of a droplet by breaking up a liquid bridge formed by electric induction

et al. 2010

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Dispensing uniform pico-to-nanoliter droplets has become one of essential components in various application fields from high-throughput bio-analysis to printing. In this study, a new method is suggested and demonstrated for dispensing a droplet on the top plate with an inverted geometry by using electric field. The process of dispensing droplets consists of two stages: (i) formation of liquid bridge by moving up the charged fluid mass using the electrostatic force between the charges on the fluid mass and the induced charges on the substrate and (ii) its break-up by the motion of the top plate. Different from conventional electrohydrodynamic methods, electric induction enables the droplets to be dispensed on various surfaces including non-conducting substrate. The use of capillarity with an inverted geometry removes the need of external pumps or elaborates control for constant flow feed. The droplet diameter has been characterized as a function of the nozzle-to-plate distance and the plate moving velocity. The robustness of the present method is shown in terms of nozzle length and applied voltage. Finally, its practical applicability is confirmed by rendering a 19 by 24 array of highly uniform droplets with only 1.8% size variation without use of any active feedback control.

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“…One strong point of EWOD is that dispensing of daughter droplets from a mother drop is well developed (although it is possible for sandwiched type EWOD platform only), which is one of essential parts of digital microfluidic technology. Fortunately, there are some available dispensing mechanisms which can be applied to the ECD system such as electrospray [56] or electric charge concentration (ECC) method [108]. If a dispensing system well fitted to the ECD technology is developed, the applicability of the technology will be much promoted.…”

Section: Perspectivesmentioning

confidence: 99%

Next generation digital microfluidic technology: Electrophoresis of charged droplets

2015

Korean J. Chem. Eng.

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Contact charging of a conducting droplet in a dielectric medium is introduced as a novel and useful digital microfluidic technology as well as an interesting scientific phenomenon. The history of this phenomenon, starting from original observations to its interpretations and applications, is presented. The basic principle of the droplet contact charging is also presented. Several fundamental aspects of the droplet contact charging from view points of electrochemistry, surface science, electrocoalescence, and electrohydrodynamics are mentioned. Some promising results for future applications and potential features as a next generation digital microfluidic technology are discussed, especially for 3D organ printing. Finally, implications and significance of the proposed technology for chemical engineering community are discussed.

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Drop formation via breakup of a liquid bridge in an AC electric field

Cited by 29 publications

References 19 publications

AC electrohydrodynamic instabilities in thin liquid films

AC electrohydrodynamic instabilities in thin liquid films

Pumpless dispensing of a droplet by breaking up a liquid bridge formed by electric induction

Next generation digital microfluidic technology: Electrophoresis of charged droplets

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