Experimental studies on droplet formation in a flow-focusing microchannel in the presence of surfactants

Roumpea, Evangelia; Kovalchuk, N. M.; Chinaud, Maxime; Nowak, Emilia; Simmons, Mark; Angeli, Panagiota

doi:10.1016/j.ces.2018.09.049

Cited by 55 publications

(46 citation statements)

References 32 publications

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“…Therefore, higher viscous forces produce a greater propensity for droplet formation. Traditional 2D droplet-generator geometries accomplish this by either surrounding and stretching the dispersed phase with the continuous phase, as in co-flowing or flow-focusing droplet-generator geometries [ 29 , 30 , 31 ], or by disrupting the dispersed phase with a perpendicular flow of the continuous phase, as in T-junction droplet-generator geometries [ 32 , 33 ].…”

Section: Resultsmentioning

confidence: 99%

3D-Printed Microfluidic Droplet Generator with Hydrophilic and Hydrophobic Polymers

et al. 2021

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Droplet generation has been widely used in conventional two-dimensional (2D) microfluidic devices, and has recently begun to be explored for 3D-printed droplet generators. A major challenge for 3D-printed devices is preventing water-in-oil droplets from sticking to the interior surfaces of the droplet generator when the device is not made from hydrophobic materials. In this study, two approaches were investigated and shown to successfully form droplets in 3D-printed microfluidic devices. First, several printing resin candidates were tested to evaluate their suitability for droplet formation and material properties. We determined that a hexanediol diacrylate/lauryl acrylate (HDDA/LA) resin forms a solid polymer that is sufficiently hydrophobic to prevent aqueous droplets (in a continuous oil flow) from attaching to the device walls. The second approach uses a fully 3D annular channel-in-channel geometry to form microfluidic droplets that do not contact channel walls, and thus, this geometry can be used with hydrophilic resins. Stable droplets were shown to form using the channel-in-channel geometry, and the droplet size and generation frequency for this geometry were explored for various flow rates for the continuous and dispersed phases.

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Section: Resultsmentioning

confidence: 99%

3D-Printed Microfluidic Droplet Generator with Hydrophilic and Hydrophobic Polymers

et al. 2021

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“…Inclusion of surface active agents in SEDDSs cannot promise physical stability due to the complexation of emulsified systems sustained by surfactants. These excipients create interfacial tension gradients and provide modification to the breakup dynamics of droplets [87]. Hence, the physical stability of SEDDSs was investigated through thermodynamic stability experiments [43,54].…”

Section: Thermodynamic Stabilitymentioning

confidence: 99%

Development of a Self-Emulsifying Drug Delivery System for Optimized Topical Delivery of Clofazimine

2020

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A quality-by-design and characterization approach was followed to ensure development of self-emulsifying drug delivery systems (SEDDSs) destined for topical delivery of the highly lipophilic clofazimine. Solubility and water-titration experiments identified spontaneous emulsification capacity of different excipient combinations and clofazimine. After identifying self-emulsification regions, check-point formulations were selected within the self-emulsification region by considering characteristics required to achieve optimized topical drug delivery. Check-point formulations, able to withstand phase separation after 24 h at an ambient temperature, were subjected to characterization studies. Experiments involved droplet size evaluation; size distribution; zeta-potential; self-emulsification time and efficacy; viscosity and pH measurement; cloud point assessment; and thermodynamic stability studies. SEDDSs with favorable properties, i.e., topical drug delivery, were subjected to dermal diffusion studies. Successful in vitro topical clofazimine delivery was observed. Olive oil facilitated the highest topical delivery of clofazimine probably due to increased oleic acid levels that enhanced stratum corneum lipid disruption, followed by improved dermal clofazimine delivery. Finally, isothermal microcalometric experiments studied the compatibility of excipients. Potential interactions were depicted between argan oil and clofazimine as well as between Span®60 and argan-, macadamia- and olive oil, respectively. However, despite some mundane incompatibilities, successful development of topical SEDDSs achieved enhanced topical clofazimine delivery.

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“…Systems without surfactants can be used, but it is not always possible to have drops forming at the relevant range of flowrates and capillary numbers as interfacial tensions are high. Surfactants are added to extend the ranges of flowrates where drops form, but in this case surfactant concentrations well above the CMC values need to be used to obtain constant interfacial tension [18,21,22].…”

Section: Introductionmentioning

confidence: 99%

Comparison of surfactant mass transfer with drop formation times from dynamic interfacial tension measurements in microchannels

Kalli

Chagot

Angeli

2022

Journal of Colloid and Interface Science

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Experimental studies on droplet formation in a flow-focusing microchannel in the presence of surfactants

Cited by 55 publications

References 32 publications

3D-Printed Microfluidic Droplet Generator with Hydrophilic and Hydrophobic Polymers

3D-Printed Microfluidic Droplet Generator with Hydrophilic and Hydrophobic Polymers

Development of a Self-Emulsifying Drug Delivery System for Optimized Topical Delivery of Clofazimine

Comparison of surfactant mass transfer with drop formation times from dynamic interfacial tension measurements in microchannels

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