Self-assembled and repeatable sers nanoprobes on fibre tip

We report on the fabrication and repeatability assessment of patterned substrates onto the optical fibre tip for surface-enhanced Raman spectroscopy (SERS) applications. In the route of "Lab on Fiber" Technology, indeed, we developed a simple an inexpensive self-assembly technique to create ordered and regular nanostructures on the optical fibre tip. The fabrication technique is borrowed from nanosphere lithography and it is adapted to operate on the cleaved end of standard optical fibre tips. This technique has been used to create different nanostructures with completely different morphological features on the fibre tip. The repeatability of the fabricated structures is here analyzed by using Focused Ion Beam Microscopy (FIBM) and Atomic Force Microscopy (AFM). The morphological analysis allowed to assess the nanospheres pattern regularity by systematically measuring the nanostructures features sizes and the number of defect for unit area. The analyzed samples have been also characterized spectrally to quantify the effective impact of the defect formation on the samples spectral response. Finally, the capability of the samples to act as SERS probes has been verified by detecting low concentrations (1 μM) of Crystal Violet diluted in an aqueous solution.