Investigation of Au nanoparticles assembled on periodic wrinkled PDMS as a flexible SERS substrate

Au nanoparticles were easily assembled on a flexible periodic wrinkled PDMS surface without the need for expensive templates or the adoption of complicated surface modifications. The influences of the UVO treatment time, prestretch deformation and total film thickness on the structure of the PDMS wrinkles were investigated by SEM. Au nanoparticle assembly was conducted either on previously wrinkled PDMS surfaces or during the wrinkle-formation process. It was revealed that the compressive force caused by the shrinkage of the elastic PDMS promoted the assembly of Au nanoparticles into chains. Meanwhile, Au nanoparticles, in turn, significantly affected the surface morphology evolution of PDMS when the hard oxidic top layer was thin and consequently fractal structures rather than wrinkles were produced, which have rarely been reported. SERS investigations demonstrated that these PDMS-based periodic substrates displayed much stronger enhancement properties than did Au colloids in solution.