Dynamics of rigid microparticles at the interface of co-flowing immiscible liquids in a microchannel

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

doi:10.1016/j.jcis.2017.01.034

Cited by 10 publications

(10 citation statements)

References 36 publications

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“…Sorting of droplets based on size contrast is demonstrated as well. Later, they reported the dynamical migration behavior of rigid polystyrene microparticles at an interface of coflowing streams of primary (aqueous) and secondary (oils) immiscible phases at low Reynolds numbers in a microchannel 104 . They found that the migration criterion depends on the sign of the spreading parameter and the presence of surfactant at the interface, and the interfacial perturbation can cause detachment of microparticles from the interface.…”

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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“…This is because at higher droplet velocity the residence time of a droplet in the electric-field region becomes smaller and the droplet does not spend enough time for the complete drainage of the thin film between the droplet and interface. At a higher droplet velocity, the flow capillary number Ca = μ m γa /γ̇ increases due to which the coalescence time also increases . Here μ m is the viscosity of continuous phase CP 1 , γ is the interfacial tension of droplet–CP 1 interface, a is the droplet radius, and γ̇ is the shear rate.…”

Section: Results and Discussionmentioning

confidence: 99%

“…Here μ m is the viscosity of continuous phase CP 1 , γ is the interfacial tension of droplet–CP 1 interface, a is the droplet radius, and γ̇ is the shear rate. However, to coalesce the faster moving droplets within this short residence time available, the droplet electrocapillary number Ca E = ε m aE 0 2 /γ needs to be higher . Here ε m is the permittivity of continuous phase CP 1 and E 0 is the applied electric field.…”

Section: Results and Discussionmentioning

confidence: 99%

“…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%

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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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“…The viscosity of CP 1 ( μ CP1 ) is much greater than the viscosity of CP 2 ( μ CP2 ); thus, irrespective of the flow rates, the maximum velocity (i.e., region of zero shear) of the coflow always lies in the CP 2 . Using a coflowing system of two immiscible phases, extraction of rigid polystyrene particles (from aqueous phase to oil phase) 23 and soft hydrogel microparticles (from oil phase to aqueous phase) 24 has been demonstrated, at low Re, in which the working principle was based on the interfacial properties of the liquid phases and the particle. In contrast, here, we have employed hydrodynamic (noninertial lift) force that acts on the deformable objects at low Re to selectively sort droplets of interest.…”

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

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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Dynamics of rigid microparticles at the interface of co-flowing immiscible liquids in a microchannel

Cited by 10 publications

References 36 publications

Recent progress of particle migration in viscoelastic fluids

Recent progress of particle migration in viscoelastic fluids

Droplet Demulsification Using Ultralow Voltage-Based Electrocoalescence

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

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