Controllable preparation of monodisperse microspheres using geometrically mediated droplet formation in a single mold

We present a surfactant-free fabrication method for simultaneous generation of monodisperse microspheres with controllable size manner. Droplets that become microspheres by solidification processes are made in a two-step process: capillary rising-induced fluid division and wetting of immiscible fluid in a micromold. Design of the mold geometry and the monomer concentration primarily determines the microsphere size and the size distribution. Furthermore, the synergistic effect of two parameters is able to efficiently manipulate the microsphere sizes from submicrometers to a few hundred micrometers.