Experimental study on electric-field-induced droplet generation and breakup in an immiscible medium

Wang, Dongbao; Wang, Junfeng; Yongphet, Piyaphong; Wang, Xiaoying; Zuo, Ziwen; Li, Bin; Zhang, Wei

doi:10.1007/s00348-020-2908-x

Cited by 9 publications

(5 citation statements)

References 39 publications

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“…In addition to generating simple tiny single droplets or particles, these techniques can be used to make more complex droplets, such as double droplets [ 141 , 155 ], and thus many studies have been conducted in the fields of bioengineering [ 156 ], medical [ 157 ], and pharmaceutical [ 141 ]. Similarly, breakup at high voltage was observed in free-emulsion droplets [ 15 ] or emulsion droplets anchored on a nozzle [ 158 , 159 ] ( Figure 10 A,B). The droplet that is stretched under a strong electric field produces tiny daughter droplets at both ends, which is called tip streaming [ 15 , 25 ].…”

Section: Applicationsmentioning

confidence: 78%

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Electro-Hydrodynamics of Emulsion Droplets: Physical Insights to Applications

et al. 2020

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The field of droplet electrohydrodynamics (EHD) emerged with a seminal work of G.I. Taylor in 1966, who presented the so-called leaky dielectric model (LDM) to predict the droplet shapes undergoing distortions under an electric field. Since then, the droplet EHD has evolved in many ways over the next 55 years with numerous intriguing phenomena reported, such as tip and equatorial streaming, Quincke rotation, double droplet breakup modes, particle assemblies at the emulsion interface, and many more. These phenomena have a potential of vast applications in different areas of science and technology. This paper presents a review of prominent droplet EHD studies pertaining to the essential physical insight of various EHD phenomena. Here, we discuss the dynamics of a single-phase emulsion droplet under weak and strong electric fields. Moreover, the effect of the presence of particles and surfactants at the emulsion interface is covered in detail. Furthermore, the EHD of multi-phase double emulsion droplet is included. We focus on features such as deformation, instabilities, and breakups under varying electrical and physical properties. At the end of the review, we also discuss the potential applications of droplet EHD and various challenges with their future perspectives.

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Section: Applicationsmentioning

confidence: 78%

“… Applications of electro-hydrodynamics (EHD) of emulsion droplets. ( A ) Electric-field-induced breakup of a liquid column from a nozzle, and small droplet formation behavior [ 158 ]. ( B ) Electric production of emulsion droplets in a microfluidic system [ 161 ].…”

Section: Figurementioning

confidence: 99%

Electro-Hydrodynamics of Emulsion Droplets: Physical Insights to Applications

et al. 2020

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“…Droplet generation methods can be divided into active and passive categories based on the exerting forces . Active approaches mainly employ external forces to generate droplets, such as electric, magnetic, and sound fields. − Passive approaches mainly design different microchannel structures and employ extrusion or shearing forces of the continuous phase to destabilize and break the interface between the two-phase fluids, resulting in the droplets (or bubbles) formation . As passive methods only require two syringe pumps without auxiliary equipment, these are more conducive to manufacturing and are commonly employed to generate droplets in microchannels. , The influence factors on the droplet size and force mechanism have been extensively investigated, including the channel structure, wall wettability, two-phase flow rates, and fluid physical properties (viscosity, interfacial tension, and surfactant). , …”

Section: Introductionmentioning

confidence: 99%

Easy Generation of Droplets in a Capillary Inserted Microchannel

Shen,

Chen,

et al. 2024

Ind. Eng. Chem. Res.

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Droplet microfluidics has received increasing attention over the past decade. This study proposes an easy method for droplet generation in microchannels by inserting a glass capillary into a microfluidic chip at required positions. The influences of the capillary insertion depth (0, 60, and 120 μm), capillary inner diameter (50, 75, and 100 μm), and two-phase flow rate ratios (2–12) on the generated droplet length were investigated. The evolution of the two-phase interface during droplet formation is observed in detail, which undergoes three successive stages: head formation, head filling, and neck breakage. Three neck breakage modes were identified as the squeezing, transition, and dripping modes, and the forces acting on the droplets were analyzed. The results show that the proposed capillary-based method can facilitate the generation of droplets in fabricated microfluidic chips over a wide range of two-phase flow rate ratios.

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“…Droplet formation is performed by passive 6 or active 7 methods, which differ in the absence or presence of an external force. Electrical 8 , magnetic 9 , and acoustic 10 forces have been the most external stimuli in the active methods.…”

Section: Introductionmentioning

confidence: 99%

On-demand ferrofluid droplet formation with non-linear magnetic permeability in the presence of high non-uniform magnetic fields

Bijarchi

Yaghoobi

Favakeh

2022

Sci Rep

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The magnetic actuation of ferrofluid droplets offers an inspiring tool in widespread engineering and biological applications. In this study, the dynamics of ferrofluid droplet generation with a Drop-on-Demand feature under a non-uniform magnetic field is investigated by multiscale numerical modeling. Langevin equation is assumed for ferrofluid magnetic susceptibility due to the strong applied magnetic field. Large and small computational domains are considered. In the larger domain, the magnetic field is obtained by solving Maxwell equations. In the smaller domain, a coupling of continuity, Navier Stokes, two-phase flow, and Maxwell equations are solved by utilizing the magnetic field achieved by the larger domain for the boundary condition. The Finite volume method and coupling of level-set and Volume of Fluid methods are used for solving equations. The droplet formation is simulated in a two-dimensional axisymmetric domain. The method of solving fluid and magnetic equations is validated using a benchmark. Then, ferrofluid droplet formation is investigated experimentally, and the numerical results showed good agreement with the experimental data. The effect of 12 dimensionless parameters, including the ratio of magnetic, gravitational, and surface tension forces, the ratio of the nozzle and magnetic coil dimensions, and ferrofluid to continuous-phase properties ratios are studied. The results showed that by increasing the magnetic Bond number, gravitational Bond number, Ohnesorge number, dimensionless saturation magnetization, initial magnetic susceptibility of ferrofluid, the generated droplet diameter reduces, whereas the formation frequency increases. The same results were observed when decreasing the ferrite core diameter to outer nozzle diameter, density, and viscosity ratios.

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Experimental study on electric-field-induced droplet generation and breakup in an immiscible medium

Cited by 9 publications

References 39 publications

Electro-Hydrodynamics of Emulsion Droplets: Physical Insights to Applications

Electro-Hydrodynamics of Emulsion Droplets: Physical Insights to Applications

Easy Generation of Droplets in a Capillary Inserted Microchannel

On-demand ferrofluid droplet formation with non-linear magnetic permeability in the presence of high non-uniform magnetic fields

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