Polygonal microstructures self-assembled from evaporating picoliter droplets in micro cavities

We reports the experimental results of the novel polygonal microstructures self-assembled from the evaporating picoliter droplets in micro-scale cavities. Utilizing the inkjet-like method, the drop-on-demand (DOD) droplets of colloidal polymers (Polyurethane, PU 15% in volume) can be precisely positioned into the constrained regions on the polymeric (Polydimethysiloxane, PDMS) substrates which are patterned by current (soft-)lithography technique. The novel various microstructures in polygonal (tri-to hexagonal) forms are created and characterized with specifically optical performances applicable to the potential micro devices such as microlenses and mirrors.