Wrinkled Ag nanostructured gratings towards single molecule detection by ultrahigh surface Raman scattering enhancement

A novel triangular cross-section Ag nanostructured grating is demonstrated in this paper, which can be used as an extremely high sensitivity bio-chemical sensing substrate. Ag films with a thickness of several nanometers and up to 40 nm were sputtered on a pre-strained PDMS substrate. After releasing the PDMS, the Ag films wrinkled and sharp structures were formed due to the mechanical stress on the continuous thin metallic nano films. Because of the electromagneticfield enhancement at the sharp peaks, extremely high Surface Enhanced Fluorescence (SEF) and Surface Enhanced Raman Scattering (SERS) was observed which can be used to detect Crystal Violet (CV) and Rhodamine 6G (R6G) molecules with concentrations down to 10−14 M. The method provides an effective and inexpensive technique to create wrinkled periodic singular patterns for various applications.