Prediction and control of drop formation modes in microfluidic generation of double emulsions by single-step emulsification

Abstract

A non-dimensional parameter (ζ) for prediction of double emulsion formation mode as a function of the capillary numbers of all fluids and device geometry was developed and its critical values were determined using simulation and experimental data. At logζ>5.7, drops were formed in dripping mode; the widening jetting occurred at 5<logζ<5.7; while the narrowing jetting was observed at logζ<5. The ζ criterion was correlated with the ratio of the break-up length to drop diameter. The transition from widening to narrowing jetting was achieved by increasing the outer fluid flow rate at the high capillary number of the inner fluid. The drop size was reduced by reducing the distance between the two inner capillaries and the minimum drop size was achieved when the distance between the capillaries was zero.

Modelling double emulsion formation in planar flow-focusing microchannels

“…Complementary to experiments, numerical studies on double emulsion formation dynamics in microfluidic channels have also garnered strong interest. For instance, great efforts were made to elucidate the effects of flow rates, interfacial tension ratios, geometry (Chen, Wu & Lin 2015;Nabavi et al 2015b) and viscosities (Fu et al 2016) on the double emulsion properties and the flow regime predictions (Nabavi et al 2017a) for coaxial flow-focusing capillary devices. Simulations are particularly advantageous for providing accurate flow details and for allowing each Double emulsion formation in flow-focusing microchannels 895 A22-3 relevant parameter in the system to be varied systematically.…”

Droplet-based microfluidic method for robust preparation of gold nanoparticles in axisymmetric flow focusing device

“…8b), due to the lower shear from the surrounding oil phase. The smallest droplets were generated when the positions of the two orifices coincided, because the reaction mixture experienced the highest shear (Nabavi et al, 2017). Fig.…”

Evaluating the Stability of Double Emulsions—A Review of the Measurement Techniques for the Systematic Investigation of Instability Mechanisms

“…Microfluidic devices allow for producing double emulsions of defined droplet size und filling degree [64][65][66]. Either symmetrical glass capillaries (e.g., [67][68][69][70][71]) or Polydimethylsiloxane chips (e.g., [64,72,73]) have been proposed for this task. In contrast to double emulsions produced by typical industrial processing machines, oil droplets contain a smaller number of inner water droplets.…”