Optofluidic Encapsulation of Crystalline Colloidal Arrays Using Photocurable Double Emulsion Droplets

Microfluidic devices composed of glass capillaries were used for generation of double emulsion droplets with photocurable shell phase. The cores of the emulsion droplets were aqueous suspension of higly charged polystyrene (PS) particles which readily form the crystals by repulsive interparticle potential. The shells of double emulsion droplets were solidified downstream and formed the polymeric membranes which can keep the crystals from external disturbances such as ionic impurities. Especially, encapsulated crystals in liquid phase showed distinctive diffraction pattern unlike conventional film type crystals owing to heterogeneous nucleation at the spherical wall of the capsules during crystallization of colloids.