3D silver metallized nanotrenches fabricated by nanoimprint lithography as flexible SERS detection platform

We report the development of highly sensitive substrates with great potential as Surface-enhanced Raman scattering (SERS) spectroscopy detection platforms, consisting of nanoimprint lithography (NIL) fabricated nanotrenches in plastic and covered by nanostructured silver (Ag) films with thicknesses in the 10-100 nm range deposited by direct current (DC) sputtering. The Ag film thickness was increased by using sequential deposition times and its contribution to the obtained enhancement factor was deter-mined. The morphological and structural properties of the metalized nanotrenches were assessed by scanning electron microscopy (SEM) and atomic force microscopy (AFM) techniques. Crystal violet (CV) was used as analyte to test the SERS activity of the substrates prepared with or without the nanoim-printed pattern. Our original approach was to determine the resulted SERS enhancement from the syn-ergy of three key aspects: the Ag metallization of cheap, flexible substrates, the effect of increasing the Ag film thickness and the periodic nanotrenches imprinted by NIL as substrate. We found a dramatical contribution in the SERS signal of the periodical Ag nanopattern in comparison to the Ag film quantified by a calculated enhancement factor (EF) up to 107 in case of the SERS detection platform with a 25 nm Ag layer on top of the periodic nanotrenches. The contribution of plasmonic nanostructures contained in the Ag films as well as the contribution of the periodical nanopatterned trenches was assessed, as a cumula-tive effect to the first contribution. This substrate showed a considerably lower limit of detection (LOD) for SERS, down to 10 pM, much better uniformity as well as more reproducible signals in comparison with the other thicknesses of the metallic film. (C) 2022 Elsevier B.V. All rights reserved.

Automated summary

In this study, highly sensitive substrates with potential as Surface-enhanced Raman scattering (SERS) detection platforms were developed using nanoimprint lithography nanotrenches in plastic and nanostructured silver (Ag) films. The contribution of the periodic Ag nanopattern in the SERS signal was found to be significant, with an enhancement factor (EF) of up to 107 for the SERS detection platform with a 25 nm Ag layer on top of the periodic nanotrenches. The substrate showed a considerably lower limit of detection (LOD) for SERS and better signal uniformity and reproducibility.