Double Emulsion Generation

What is double emulsion generation?

Double emulsion, water-in-oil-in-water emulsions, are three-phase dispersions composed of inner aqueous droplets dispersed in larger oil droplets, which are themselves dispersed in another aqueous phase. The presence of intermediate (middle) fluid as a protective shell or semi permeable barrier which separates the inner aqueous phase from the outer one, makes double emulsions suitable in a wide range of applications including food, cosmetics, encapsulation of water-soluble therapeutic agents for targetable drug delivery, preparation of biodegradable microcapsules loaded with bioactive polymers, extraction of hydrocarbons, metal ions, and organic acids across a thin liquid layer mediating between the internal drops and the external continuous phase… 

Conventional double emulsion production methods such as high-shear homogenizers and colloid mill are based on high shear mixing of immiscible liquids. These devices, however, suffer from poor droplet size reproducibility and are not suitable for generation of core/shell droplets. Recently, microfluidic emulsification devices have attracted much attention due to their unprecedented level of control over droplet size and morphology. In microfluidic devices, droplets can be produced in two main regimes, dripping and jetting, depending on the balance between interfacial, viscous, inertial and gravity forces.