Micropatterns of colloidal assembly on chemically patterned surface

Micropatterns of colloidal assembly were fabricated by the wetting/dewetting of suspensions on chemically patterned polydimethylsiloxane (PDMS). With the aid of plasma oxidation using screen masks, we fabricated the hydrophilic/hydrophobic patterns on the PDMS surface and dropped the suspensions of colloidal particles (210 or 410 nm diameter particles on such patterned substrate). In the evaporation process, the colloidal suspensions were split and drawn from the hydrophobic domains to the hydrophilic domains via the wetting/dewetting process, and wetted only the hydrophilic domains to form an ordered colloidal assembly. In our experimental, the aqueous suspension with ethanol offered better results of the microarrays of colloidal assembly with ordered microstructures because of the low surface tension and fast evaporation rate of ethanol. The proposed method was applied to fabricate the micropatterns of colloidal assembly with various size of colloidal particles and patterned domains.