Introducing ‘low cost large scale’ hydrophobic SERS substrate

Abstract

Large-area nano-patterned surfaces invoking hydrophobicity hold great significance for Surface Enhanced RamanSpectroscopy or SERS substrates. Conventionally, these structures are fabricated using state-of-the-art litho-graphic techniques. These techniques while being efficient, are complex and are cost-ineffective. Here, we report a low-cost, facile and scalable solution for fabrication of periodic array of metallic nanocones using colloidal lithography and reactive ion etching process. Nanocone array coated with gold thin film serves as a hydrophobicsurface with plasmonic properties. Hydrophobicity on the cones helps to keep the analyte molecule localized near the tip of nanocones where, due to plasmonic behavior of metal thin film i.e. field enhancement by the metal gives rise to significant SERS. We validate this concept through our fabricated substrate via detection ofRhodamine 6G molecules using Raman spectroscopy and report the limit of detection upto 1 nM.