Multifunctional plasmonic sensors on low-cost subwavelength metallic nanoholes arrays.

Localized surface plasmon resonance (LSPR) sensing is combined with surface enhanced Raman scattering (SERS) detection on periodic arrays of subwavelength metallic nanoholes for the first time. LSPR sensors provide detection of molecular adsorption in both transmission and reflectivity modes with sensitivity greater that 300 nm/RIU and a spectral shift of 16 nm in the case of binding a monolayer of p-aminothiophenol (p-ATP) molecules. Subsequent SERS analysis enables identification of the adsorbed p-ATP molecule, its structure and orientation on the metal surface. This synergistic LSPR-SERS approach on low-cost metallic films perforated with periodic arrays of subwavelength nanoholes opens a route for molecular dual-modal detection to be integrated in lab-on-chip systems to increase the reliability of biological detection.