High inertial microfluidics for droplet generation in a flow-focusing geometry

Mastiani, Mohammad; Seo, Seokju; Riou, Benjamin; Kim, Myeongsub

doi:10.1007/s10544-019-0405-x

Cited by 15 publications

(6 citation statements)

References 46 publications

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“…Meanwhile, MFFD has the advantage of providing a more stable way to generate droplets with controlled sizes in dripping regime. This is because the disperse phase in MFFD is surrounded by two symmetric continuous-phase streams and does not wet the sidewalls 41,42 , while the disperse phase in a T-junction device stays in contact with one of the sidewalls and eventually wets the sidewall to affect the formation of droplets 43 .…”

Section: Resultsmentioning

confidence: 99%

Polymer Capsules with Tunable Shell Thickness Synthesized via Janus-to-core shell Transition of Biphasic Droplets Produced in a Microfluidic Flow-Focusing Device

Nisisako

2020

Sci Rep

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Droplet microfluidics has enabled the synthesis of polymeric particles with controlled sizes, shell thickness, and morphologies. Here, we report the Janus to core-shell structural evolution of biphasic droplets formed in a microfluidic flow-focusing device (MFFD) for the synthesis of polymer microcapsules with oil core/thickness-tunable shell via off-chip photo-and thermally induced polymerization. First, nanoliter-sized biphasic Janus droplets comprising an acrylate monomer and silicone oil were generated in a co-flowing aqueous polyvinyl alcohol (PVA) solution in an MFFD on a glass chip. Immediately following their break-off, the produced Janus droplets started to change their geometry from Janus to core-shell structure comprising a single silicone-oil core and an acrylatemonomer shell by the minimization of interfacial energy. Thus, we could produce monodisperse coreshell drops with average diameters of 105-325 μm, coefficient of variation (CV) values of 1.0-4.5%, and shell thickness of 1-67 μm. Subsequently, these drops were synthesized to fabricate polymeric microcapsules with tunable shell thickness via photo-and thermally induced polymerization. By increasing the concentration of the photo-and thermal initiator, we successfully produced thinner and ultra-thin shell (800 nm thickness) microcapsules. The surface structure of resulting particles was smooth in photopolymerization and porous in thermal polymerization. Microcapsules with core-shell structures, in which the active substances in cores are protected by the shells from the outer environment, have been applied in numerous fields such as foods 1,2 , cosmetics 3,4 , pharmaceutics 5 , printing 6,7 , and self-healing materials 8,9. Microcapsules can be synthesized via a variety of techniques including spray drying 10 , layer-by-layer deposition 11 , interfacial polymerization 12 , coacervation 13 , or membrane emulsification 14. Although these techniques can provide a high throughput, it remains difficult to fabricate uniform microcapsules with controlled size and high encapsulation efficiency. Recently, droplet microfluidics has been shown to provide a new and promising route to synthesize microcapsules. Using microfluidic technology, one can easily produce monodisperse core-shell droplets as ideal templates for fabricating microcapsules via subsequent various solidification methods; examples of the solidification methods include photo or thermally induced free-radical polymerization 15,16 , solvent evaporation 17 , freezing 18 , and ironic cross-linking 19. So far, the core-shell templates were prepared in two-step or one-step droplet formation. In the two-step method, using two T-junctions 20,21 , two flow-focusing junctions 22,23 , two co-flowing junctions 24 , or three-dimensional devices 25 , core drops are generated at first and then shell drops encapsulating these core drops are produced in a continuous phase as a separate step. Using this two-step approach, for example, acrylic capsules with aqueous cores with diameters of 10-340 µm and CVs ~5% ...

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Section: Resultsmentioning

confidence: 99%

Polymer Capsules with Tunable Shell Thickness Synthesized via Janus-to-core shell Transition of Biphasic Droplets Produced in a Microfluidic Flow-Focusing Device

Nisisako

2020

Sci Rep

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“…Low values of the capillary number are the result of the prevalence of the interfacial tension over the viscous forces, translating into stable and persistent bubbles. 55 The bubbles produced during the motion of uniform bubbles (Fig. 5Q and R) had the highest stability compared to the flows with non-uniform bubbles presented in Fig.…”

Section: Resultsmentioning

confidence: 84%

“…4 is the result of the balance of dominant forces, as reported elsewhere. 55 Fig. S21 and S22 † illustrate the 3D histograms representing air bubble volume in relation to the injected air pressure.…”

Section: Parameters Of the Air Bubble Displacement In T-and Y-junctio...mentioning

confidence: 99%

Investigation of air bubble behaviour after gas embolism events induced in a microfluidic network mimicking microvasculature

Mardanpour,

Sudalaiyadum Perumal,

Mahmoodi

et al. 2024

Lab Chip

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“…Nevertheless, some physical and geometrical parameters will cause this regime to undergo variations, which we call instabilities. Another form of instability in the dripping regime is inherent to flow-focusing droplet generators [ 38 ]. One example of such instability is shown in Figure 7 and Video S1 .…”

Section: Resultsmentioning

confidence: 99%

“…There are several extensive numerical and experimental studies that have proposed a correlation between

, and

[ 3 , 18 , 21 , 38 ]; that is,

. We know that

.…”

Section: Model Description and Methodsmentioning

confidence: 99%

An Interface–Particle Interaction Approach for Evaluation of the Co-Encapsulation Efficiency of Cells in a Flow-Focusing Droplet Generator

Yaghoobi

Saidi

Ghadami

et al. 2020

Sensors

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Droplet-based microfluidics offers significant advantages, such as high throughput and scalability, making platforms based on this technology ideal candidates for point-of-care (POC) testing and clinical diagnosis. However, the efficiency of co-encapsulation in droplets is suboptimal, limiting the applicability of such platforms for the biosensing applications. The homogeneity of the bioanalytes in the droplets is an unsolved problem. While there is extensive literature on the experimental setups and active methods used to increase the efficiency of such platforms, passive techniques have received less attention, and their fundamentals have not been fully explored. Here, we develop a novel passive technique for investigating cell encapsulation using the finite element method (FEM). The level set method was used to track the interfaces of forming droplets. The effects of walls and the droplet interfaces on relatively large cells were calculated to track them more accurately during encapsulation. The static surface tension force was used to account for the effects of the interfaces on cells. The results revealed that the pairing efficiency is highly sensitive to the standard deviation (SD) of the distance between the cells in the entrance channel. The pairing efficiency prediction error of our model differed by less than 5% from previous experiments. The proposed model can be used to evaluate the performance of droplet-based microfluidic devices to ensure higher precision for co-encapsulation of cells.

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High inertial microfluidics for droplet generation in a flow-focusing geometry

Cited by 15 publications

References 46 publications

Polymer Capsules with Tunable Shell Thickness Synthesized via Janus-to-core shell Transition of Biphasic Droplets Produced in a Microfluidic Flow-Focusing Device

Polymer Capsules with Tunable Shell Thickness Synthesized via Janus-to-core shell Transition of Biphasic Droplets Produced in a Microfluidic Flow-Focusing Device

Investigation of air bubble behaviour after gas embolism events induced in a microfluidic network mimicking microvasculature

An Interface–Particle Interaction Approach for Evaluation of the Co-Encapsulation Efficiency of Cells in a Flow-Focusing Droplet Generator

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