Dynamics of Aqueous Droplets at the Interface of Coflowing Immiscible Oils in a Microchannel

Jayaprakash, Karamil; Banerjee, Utsab; Sen, A. K.

doi:10.1021/acs.langmuir.5b04116

Cited by 29 publications

(23 citation statements)

References 19 publications

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“…Particle focusing and separation using sample-sheath flow with the same fluid property (either Newtonian fluids or non-Newtonian fluids) has been explored extensively, while sample-sheath flow with different fluid properties has rarely been studied. Jayaprakash et al 103 investigated the dynamics of aqueous droplets of different size and viscosity at the interface of a coflowing stream of immiscible oils (silicone oil as primary and mineral oil as secondary continuous phases). They elaborated that the competing noninertial lift and interfacial tension forces governs the interfacial migration of the droplets.…”

Section: Particle Solution Exchangementioning

confidence: 99%

Recent progress of particle migration in viscoelastic fluids

et al. 2018

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Recently, research on particle migration in non-Newtonian viscoelastic fluids has gained considerable attention. In a viscoelastic fluid, three dimensional (3D) particle focusing can be easily realized in simple channels without the need for any external force fields or complex microchannel structures compared with that in a Newtonian fluid. Due to its promising properties for particle precise focusing and manipulation, this field has been developed rapidly, and research on the field has been shifted from fundamentals to applications. This review will elaborate the recent progress of particle migration in viscoelastic fluids, especially on the aspect of applications. The hydrodynamic forces on the micro/nano particles in viscoelastic fluids are discussed. Next, we elaborate the basic particle migration in viscoelasticity-dominant fluids and elasto-inertial fluids in straight channels. After that, a comprehensive review on the applications of viscoelasticity-induced particle migration (particle separation, cell deformability measurement and alignment, particle solution exchange, rheometry-on-a-chip and others) is presented; finally, we thrash out some perspectives on the future directions of particle migration in viscoelastic fluids.

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Section: Particle Solution Exchangementioning

confidence: 99%

Recent progress of particle migration in viscoelastic fluids

et al. 2018

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“…The interfacial migration of the droplets would depend on the ratio of the above two forces k ( μ CP1 _ γR 2 )=σy, which can give rise to selective migration depending on the size and viscosity ratio of the droplets as described in our previous works. 22,31 The controlling parameters which govern the interfacial migration from CP 1 to CP 2 are the strain rate _ γ and the radius of the droplet R. The strain rates can be varied by varying the flow rates of the continuous phases. From the expression of the force ratio, we see that the noninertial lift force is a strong function of droplet radius.…”

Section: Sorting Of Positive and Negative Droplets Encapsulating Particles And Cells Based On Size Contrastmentioning

confidence: 99%

“…Finally, the size contrast between the positive and negative droplets is exploited to demonstrate size-based sorting. 22…”

Section: Introductionmentioning

confidence: 99%

Droplet encapsulation of particles in different regimes and sorting of particle-encapsulating-droplets from empty droplets

Jayaprakash

Sen

2019

Biomicrofluidics

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Encapsulation of microparticles in droplets has profound applications in biochemical assays. We investigate encapsulation of rigid particles (polystyrene beads) and deformable particles (biological cells) inside aqueous droplets in various droplet generation regimes, namely, squeezing, dripping, and jetting. Our study reveals that the size of the positive (particle-encapsulating) droplets is larger or smaller compared to that of the negative (empty) droplets in the dripping and jetting regimes but no size contrast is observed in the squeezing regime. The size contrast of the positive and negative droplets in the different regimes is characterized in terms of capillary number Ca and stream width ratio ω (i.e., ratio of stream width at the throat to particle diameter ω ¼ w=d p ). While for deformable particles, the positive droplets are always larger compared to the negative droplets, for rigid particles, the positive droplets are larger in the dripping and jetting regimes for 0:50 ω 0:80 but smaller in the jetting regime for ω , 0:50. We exploit the size contrast of positive and negative droplets for sorting across the fluid-fluid interface based on noninertial lift force (at Re ( 1), which is a strong function of droplet size. We demonstrate sorting of the positive droplets encapsulating polystyrene beads and biological cells from the negative droplets with an efficiency of ∼95% and purity of ∼65%. The proposed study will find relevance in single-cell studies, where positive droplets need to be isolated from the empty droplets prior to downstream processing.

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“…It comprises two inlet channels (inlets 1 and 2) leading to a wider main channel. Emulsions of aqueous droplets (as the discrete phase (DP)) present in an oil (containing surfactant for droplet stabilization) as primary continuous phase (CP 1 ) is infused into inlet 1 and aqueous phase (DI water) is infused into inlet 2 as secondary continuous phase (CP 2 ), thus forming a planar water–oil interface in the expanded channel. , A pair of electrodes is located at some location along the expanded channel. In the absence of electric field, the aqueous droplets, which are stabilized with a surfactant monolayer, do not coalesce with the aqueous phase.…”

Section: Theorymentioning

confidence: 99%

Droplet Demulsification Using Ultralow Voltage-Based Electrocoalescence

et al. 2018

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Demulsification of droplets stabilized with surfactant is very challenging due to their low surface energy. We report ultralow voltage-based electrocoalescence phenomenon for the demulsification of aqueous droplets with an aqueous stream. In the absence of electric field, due to the disjoining pressure resulting from the tail-tail interaction between the surfactant molecules present on the aqueous droplets and interface, coalescence of aqueous droplets with the aqueous stream is prevented. However, above a critical electric field, the electrical stress overcomes the disjoining pressure, thus leading to the droplet coalescence. The influence of surfactant concentration, droplet diameter, and velocity on the electrocoalescence phenomena is studied. The macroscopic contact between the aqueous droplet with the aqueous stream enables droplet coalescence at much lower voltage (10 to 90 V), which is at least two orders of magnitude smaller than voltages used in prior works (1.0 to 3.0 kV). The electrocoalescence phenomena is used for the extraction of microparticles encapsulated in aqueous droplets into the aqueous stream and size-based selective demulsification. A new paradigm of droplet electrocoalescence and content extraction is presented that would find significant applications in chemistry and biology.

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Dynamics of Aqueous Droplets at the Interface of Coflowing Immiscible Oils in a Microchannel

Cited by 29 publications

References 19 publications

Recent progress of particle migration in viscoelastic fluids

Recent progress of particle migration in viscoelastic fluids

Droplet encapsulation of particles in different regimes and sorting of particle-encapsulating-droplets from empty droplets

Droplet Demulsification Using Ultralow Voltage-Based Electrocoalescence

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