Flow-field dynamics during droplet formation by dripping in hydrodynamic-focusing microfluidics

Fünfschilling, Denis; Debas, Hélène; Li, H.-Z.; Mason, Thomas G.

doi:10.1103/physreve.80.015301

Cited by 51 publications

(29 citation statements)

References 19 publications

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“…These measurements validate the squeezing mechanism given previously. As already observed in the flow-focusing junction [18,23], a satellite droplet was formed just after the main droplet [ Fig. 2(g)] for the three configurations of fluid injection.…”

Section: Resultssupporting

confidence: 79%

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Effect of the fluid injection configuration on droplet size in a microfluidic T junction

Carrier

Fünfschilling

2014

Phys. Rev. E

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The effect of confinement on the droplet formation in T junctions was studied for three configurations of fluid injection. The sizes of the main droplets and the satellite droplets were measured in the squeezing and dripping regimes. The evolution of droplet sizes with capillary number in the continuous phase is similar to that in flow-focusing junctions, i.e., the size of the main droplets decreases with an increase of this capillary number, while the size of the satellite droplets increases with an increase of this capillary number. While in the range of flow rates investigated the injection configuration does not exhibit a significant effect on the main droplet sizes, it does have an effect on the size of the satellite droplets. The latter ones are smaller when the neck rupture of the droplet occurs on an angle of the microsystem.

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Section: Resultssupporting

confidence: 79%

“…Sometimes, the generation of droplets in microsystems leads to the formation of one or several satellite droplets besides the main droplet [16][17][18]. The formation of such satellite droplets has not been often studied in flow-focusing or T junction microsystems.…”

Section: Introductionmentioning

confidence: 99%

Effect of the fluid injection configuration on droplet size in a microfluidic T junction

Carrier

Fünfschilling

2014

Phys. Rev. E

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“…There are many different methods of creating an emulsion [55], which include: micro-fluidic devices [56][57][58], dripping drop technique [59][60][61], ultrasonication [62,63] and stirring [42].…”

Section: Types Of Emulsificationmentioning

confidence: 99%

Charge of water droplets in non-polar oils

Schoeler

Josephides

Sajjadi

et al. 2013

Journal of Applied Physics

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Recent advances in droplet manipulation methods by electric fields and signals require a deeper understanding of water droplet charge. In this paper, we have investigated the electrophoretic motion of individual water microdroplets injected into non-polar silicone and paraffin oil by video optical microscopy on an individual droplet basis to determine droplet charge. It was found that the initial surface charge density of surfactant free droplets directly after injection from a micropipette is positive and of the order of 10−6 C/m2, regardless of pH and ion concentration in the range from pH 4 to pH 10 and from 0.01 mmol/l to 1.5 mol/l, respectively. The experimental results together with molecular dynamics simulations show that the nature and polarity of the charge can be explained by anisotropic orientation of water molecules at the interface rather than selective adsorption of ions. Furthermore, we showed that slip at the liquid-liquid boundary must be taken into account when interpreting electrophoretic measurements of droplets.

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“…All the channels have a square cross section and a width of 250 mm. The flow rates of the continuous phase and the dispersed phase vary from 5 to 10 mL min 21 and from 0.2 to 1 mL min 21 , respectively. A Matlab image analysis program gives the temporal evolution of the width of the neck h(t).…”

Section: Determination Of Fluid Propertiesmentioning

confidence: 99%

“…The microfluidic flow-focusing geometry of Ref. 21 was used. The continuous phase was a m c 5 10 3 10 23 Pa.s silicon oil.…”

Section: Determination Of Fluid Propertiesmentioning

confidence: 99%

Pressure drop in a split‐and‐recombine caterpillar micromixer in case of newtonian and non‐newtonian fluids

et al. 2013

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Microreactors are very promising tools for the design of future chemical processes. For example, emulsions of very narrow size distribution are obtained at much lower energy consumption than the one spent with usual processes. Micromixers play thereby an eminent role. The goal of this study is to better understand the hydrodynamic properties of a split-and-recombine Caterpillar micromixer (CPMM) specially with regard to handling viscoelastic fluids, a topic hardly addressed so far in the context of micromixers in general, although industrial fluids like detergent, cosmetic, or food emulsions are non-Newtonian. Friction factor was measured in a CPMM for both Newtonian and non-Newtonian fluids. For Newtonian fluids, the friction factor in the laminar regime is f/2 = 24/Re. The laminar regime exists up to Reynolds numbers of 15. For shear-thinning fluids like Carbopol 940 or viscoelastic fluids like Poly Acryl Amide (PAAm) aqueous solutions, the friction factor scales identically within statistical errors up to a generalized Reynolds number of 10 and 0.01, respectively. Above that limit, there is an excess pressure drop for the viscoelastic PAAm solution. This excess pressure drop multiplies the friction factor by more than a decade over a decade of Reynolds numbers. The origin of this excess pressure drop is the high elongational flow present in the Caterpillar static mixer applied to a highly viscoelastic fluid. This result can be extended to almost all static mixers, because their flows are generally highly elongational

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Flow-field dynamics during droplet formation by dripping in hydrodynamic-focusing microfluidics

Cited by 51 publications

References 19 publications

Effect of the fluid injection configuration on droplet size in a microfluidic T junction

Effect of the fluid injection configuration on droplet size in a microfluidic T junction

Charge of water droplets in non-polar oils

Pressure drop in a split‐and‐recombine caterpillar micromixer in case of newtonian and non‐newtonian fluids

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