Fabrication of Nanostructures on Curved Surfaces Using PDMS Stamp

We report on a simple and effective process that allows direct imprinting of microand nanostructures on non-flat surfaces using flexible polymer stamps. Pattern imprinting was tried using a UV-curable polymer blend containing poly(propylene glycol) diacrylate, trimethylolpropane triacrylate and a photoinitiator. The UV-resist was dispensed manually on convex and concave surfaces of a glass lens and a concave surface of poly(methyl methacrylate). A thin, flexible polymer stamp was produced using polydimethylsiloxane (PDMS) by spin coating on a Si master containing micro/nanogratings. This PDMS stamp was used to conformally mold the UV resin on nonplanar surfaces. With this method, we have successfully demonstrated microand nanostructures down to 300 nm wide gratings, as confirmed by scanning electron microscopy and atomic force microscopy. The process so developed will fill the gap in current microand nanofabrication technologies in that most of the technologies allow for patterning only on planar substrates.