Tuneable surface enhanced Raman scattering metamaterial-like platforms via three-dimensional block copolymer based nanoarchitectures

Abstract

Surface enhanced Raman spectroscopy (SERS) pushes past the boundaries and inherent weaknesses of Raman spectroscopy, with a great potential for a broad range of applications particularly, for sensing. Yet, current real world applications are limited due to poor reproducibility, low-throughput and stability issues. Here, we present the design and fabrication of self-assembly guided structures based on adjustable block copolymer (BCP) nano-morphologies and demonstrate reproducible SERS enhancement across large areas. Golden three-dimensional (3D) nanostructured morphologies with controllable dimensions and morphologies exhibit high chemical stability, enhanced plasmonic properties and are highly suitable for SERS substrates due to the strong enhancement of the electromagnetic field. Adjustable, free standing porous nanostructures, continuous in the 3D space are achieved by removal of selected BCP constituents. Four BCP morphologies and the corresponding achievable enhancement factors are investigated at 633 and 785nm excitation wavelengths. The choice of excitation laser is shown to greatly affect the observed signal enhancement, highlighting the sensitivity of the technique to the underlying surface architecture and length scales. By using BCP assemblies, it is possible to reliably tune these parameters to match specific applications thus, bridging the gap towards the realization of applied metamaterials. The fabricated SERS platforms via three-dimensional block copolymer based nanoarchitectures provide a recipe for intelligent engineering and design of optimised SERS-active substrates for utilisation in the Raman spectroscopy-based devices towards enabling the next-generation technologies fulfilling a multitude of criteria.

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Identifiers

ORCID for Sumeet Mahajan: orcid.org/0000-0001-8923-6666

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