Fuck Yeah Double Emulsions !

"It's like catching the fish that swallowed the queen's ring", Herzog, by Saul Bellow

Elegant and mesmerizing, these double emulsions, drops inside of drops, are generated with microfluidics for studying physics, biology, chemistry, robotics, and material science.

Controlled coalescence of inner drops inside double emulsions is useful for triggering chemical reactions inside drops with the outer drops serving as reaction vessels. Merging different reagents inside nanoliter vessels is important for drug discovery of costly or scarce reagents.  Using double emulsions as micro-reactors is one of our reasons for encapsulating different types of inner drops inside another drop.

In this video, coalescence of inner drops is triggered with heat from a heat gun.  The outer drop is made of wax and as the wax melts,  the inner aqueous droplets are free to rotate and move around until they come into contact with one another.  Not shown in the video:  Eventually all the drops merge into a single drop. (Video Credit: L. L. A. Adams)