Microfluidic fabrication of microparticles with structural complexity using photocurable emulsion droplets

Polymeric microparticles with hexagonal surface patterns comprising of colloids or dimples were fabricated using photocurable emulsion droplets. Colloidal silica particles within the interior of the photocurable emulsion droplets formed two-dimensional (2D) crystals at the droplet surface by anchoring on the emulsion interface, and the resulting composite structures were captured by rapid photopolymerization. A microfluidic device composed of two coaxial glass capillaries was used to generate monodisperse microparticles, with the evolution time determining the area of the anchored colloidal silica particles on the microparticle that was exposed to the continuous phase. The exposed region of silica particles could be modified by the introduction of desired functional groups such as dye molecules through simple chemical reaction with a silane coupling agent. This ability to modify the surface should prove useful in many applications such as chemical or biomolecular screening and colloidal barcoding systems.