Radially aligned microchannels prepared from ordered arrays of cracks on colloidal films.

Arrayed microchannels with dimensions of tens to hundreds of micrometres show great potential for application in microfluidics, microreactor devices and other areas. In this work, we report the formation of ordered arrays of cracks on solution-cast colloidal films, and the preparation of radially aligned microchannels. The polymer film coating enables the colloidal film to be detached from the substrate, retaining the crack patterns on the bottom side. The subsequent chemical corrosion converts the cracks into microchannels. Crack-patterned colloidal films are also used as structured substrates for the preparation of honeycomb films by the breath figure method. Hierarchical honeycomb structures are obtained, giving rise to improved support for colloidal films.