All-aqueous core-shell droplets produced in a microfluidic device

We present a microfluidic method to compartmentalize aqueous polymer solutions within water-in-water microdroplets, which are continuously generated without using organic solvents or surfactants. Phase separation inside the drops yields all-aqueous core-shell structures (water-in-water-in-water), as we demonstrate using the aqueous two phase system of polyethylene glycol and dextran.