Double emulsion formation through hierarchical flow-focusing microchannel

Abstract

A microfluidic device is presented for creating double emulsions, controlling their sizes and also manipulating encapsulation processes. As a result of three immiscible liquids’ interaction using dripping instability, double emulsions can be produced elegantly. Effects of dimensionless numbers are investigated which are Weber number of the inner phase (Wein), Capillary number of the inner droplet (Cain), and Capillary number of the outer droplet (Caout). They affect the formation process, inner and outer droplet size, and separation frequency. Direct numerical simulation of governing equations was done using volume of fluid method and adaptive mesh refinement technique. Two kinds of double emulsion formation, the two-step and the one-step, were simulated in which the thickness of the sheath of double emulsions can be adjusted. Altering each dimensionless number will change detachment location, outer droplet size and droplet formation period. Moreover, the decussate regime of the double-emulsion/empty-droplet is observed in low Wein. This phenomenon can be obtained by adjusting the Wein in which the maximum size of the sheath is discovered. Also, the results show that Cain has significant influence on the outer droplet size in the two-step process, while Caout affects the sheath in the one-step formation considerably.

Modelling double emulsion formation in planar flow-focusing microchannels

“…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. In the literature, a number of ternary fluid models have been successfully developed and applied in the study of multiple emulsion formation behaviours, including using the volume of fluid method (Chen et al 2015;Nabavi et al 2015bNabavi et al , 2017aAzarmanesh et al 2016), the front-tracking method (Vu et al 2013), the free energy finite element method (Park & Anderson 2012) and the lattice Boltzmann method (Fu et al 2016(Fu et al , 2017.…”

Self‐Assembly of Nanoparticles in 2D and 3D: Recent Advances and Future Trends

“…Pickering double emulsions have also been prepared using block copolymer worms, [201] chemically functional hydrogel microspheres, [202] and through hierarchical flow-focusing microchannel. [203] The physicochemical attributes of transient double emulsions have been exploited to self-assemble diblock copolymers into vesicular structures [204] and to create designer liquid-liquid interfaces that can be controlled at will, even for dense particulate layers going up to multilayers and composition. [205] The controlled breakup of double emulsion droplets has also been observed while these are reinjected into another capillary device with a tapered channel.…”

Simultaneous detection of multiple HPV DNA via bottom-well microfluidic chip within an infra-red PCR platform

“…[21][22][23] Flow focusing, which uses two immiscible phases to form a large quantity of emulsions, is one of the most popular methods in the field for the generation of small individual volumes of samples. [24][25][26][27][28] This method has shown great results in the mixing study, 29 multi-emulsion a) Author to whom correspondence should be addressed: dingxianting@sjtu.edu.cn. Tel.…”