Monodisperse Double Emulsions Generated from a Microcapillary Device

TLDR

Double emulsions are structured fluids with droplets inside droplets, yet conventional two‑step fabrication yields poorly controlled structures. A microcapillary device produces core‑shell double emulsions with a single internal droplet, and by adjusting shell fluid properties it can generate encapsulation structures. Droplet size is quantitatively predictable from flow profiles, and the method’s high control and independent fluid streams make it flexible and promising.

Abstract

Double emulsions are highly structured fluids consisting of emulsion drops that contain smaller droplets inside. Although double emulsions are potentially of commercial value, traditional fabrication by means of two emulsification steps leads to very ill-controlled structuring. Using a microcapillary device, we fabricated double emulsions that contained a single internal droplet in a core-shell geometry. We show that the droplet size can be quantitatively predicted from the flow profiles of the fluids. The double emulsions were used to generate encapsulation structures by manipulating the properties of the fluid that makes up the shell. The high degree of control afforded by this method and the completely separate fluid streams make this a flexible and promising technique.