Modulated wrinkle patterns in a gold thin film deposited onto an elastomeric polymer

Modulated wrinkle patterns could be yield on a gold thin film covering an elastomeric polymer with the following simple process. The simple, efficient ultra-precision turning technique was used to prepare patterned surface of Al samples, which served as a hard master to replicate reverse patterns on the elastomeric polydimethylsiloxane (PDMS) surface by replica molding. The surface patterns in PDMS have the irregular section, different from those fabricated by optical lithography. And then a gold thin film was deposited by ion sputtering onto the patterned surface of PDMS substrates. Due to great difference in heat expansion coefficient between the metal and elastomeric polymer, modulated wrinkle patterns spontaneously appeared on the gold thin film, including stripe and herringbone. When the wavelength of the wrinkle pattern is approximately close to or more than height and width of the microstructures on the PDMS substrates, the herringbone wrinkles appear and entirely overlay the grating pattern; and otherwise the stripe pattern occurred on patterned surface of PDMS substrates and distributed perpendicularly to the step. Due to obvious difference in metal film depth, modulated wrinkle patterns, including regular striped and herringbone pattern, could be generated on gold thin films deposited onto PDMS surface.