This paper reports on a simple microcasting technique using a thin polydimethylsiloxane (PDMS) mold to fabricate a plastic butterfly wing with three-dimensional (3-D) shape. The wing consists of polyurethane (PU) frames and Parylene-C membrane, and has a curved profile. The minimum cross-sectional size of polyurethane frame was less than 100μm and the length was more than 20mm. In our method, a flexible PDMS mold with microchannels is pressed to a curved surface of a rigid lower mold to produce a 3-D structure. To estimate the deformation of the mold during pressing process, we compared the cross-sectional sizes of molded frames with those of mold channels. It was found that the change of both height and width of mold channel were small when aspect ratio of the channel was around 1.0. Using our casting technique, an artificial butterfly wing with a spherical shape was fabricated. Our method can be applied to other plastic structures which has both a macro 3-D shape and micro details.
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