Novel plasmonic nanodevices for few/single molecule detection

This paper reports the fabrication of two reproducible surface enhanced Raman scattering devices using; a) nanoPillar coupled with PC cavity by means of FIB milling and electron beam induced deposition techniques (Device 1), and b) plasmonic gold nanoaggregate structures using electro-plating and e-beam lithography techniques (Device 2). Device 1 consists of photonic crystal cavity as an optical source to couple the incident laser with a metallic tapered nanolens. Exploiting such approach it is possible to overcome the difficulties related to scattering and diffraction phenomena when visible laser (514 nm) illuminates nanostructures. The nanostructure is covered with HMDS and is selectively removed leaving HMDS polymer on nanoPillar only. A clear Raman scattering enhancement has been demonstrated for label-free detection of molecule in sub-wavelength regime. On the other hand, myoglobin protein is deposited on Device 2 using drop coating deposition method and is estimated that the substrate is able to detect the myoglobin concentration down to attomole.