A versatile multilayer liquid–liquid encapsulation technique

The encapsulating layer(s) effectively protects the water-soluble inner core (ethylene glycol) inside the water bath. A non-dimensional experimental regime is established for successful encapsulation in terms of the impact kinetic energy, interfacial layer thickness, and the viscosity ratio of the interfacial layer and the outer core liquid. Using selective fluorescent tagging, we confirm the presence of individual shell layers wrapped around the core, which presents a promising pathway to visualize the internal morphology of final encapsulated droplets.