Fabrication of monodisperse toroidal particles by polymer solidification in microfluidics.

Microdoughnuts: Polymer toroidal particles such as the one shown in the left picture have been prepared by a capillary microfluidic technique. Droplets of polymer solution undergo non-uniform solidification to form the anisotropic polymer particles. By incorporating functional materials inside the polymer network, functional toroidal particles (center and right images) can be tailor-made for specific applications such as magnetic actuation.