Hybrid modes in multilayer/antenna architecture set sideband-selective molecular Raman scattering

TL;DR

This paper investigates a hybrid multilayer plasmonic/antenna system with micrometric features that enhances sensitivity in label-free molecular Raman sensing, demonstrating improved detection of biomolecules like BSA through surface-enhanced Raman scattering.

Contribution

It introduces a novel hybrid multilayer system with surface plasmon polariton and antenna mode hybridization that improves sensitivity for biomolecular detection.

Findings

Higher sensitivity due to increased Q factor.

Effective detection of BSA protein via Raman scattering.

Surface resonance shift correlates with biomolecule presence.

Abstract

In the realm of healthcare, label-free sensing is a vital component for various applications. Micro-photonic technology presents a promising avenue to pursue pivotal goals. With the use of this technology, healthcare professionals and researchers can harness the power of label-free sensing to develop effective diagnostic and therapeutic tools. The integration of label-free sensing and micro-photonic technology can lead to revolutionary advancements in the healthcare industry. Here, a hybrid multilayer, whose surface is decorated with micrometric features has been investigated to evaluate the application in this direction. Following the characterization of the plasmonic resonance, and upon demonstrating the surface plasmon polariton (SPP)/antenna mode hybridiza-tion, the optomechanical behavior of the system has been investigated. The hybrid system has a higher sensi-tivity due to its high-quality factor Q when compared to standard systems. The shift of the frequency is studied for a red dye, at different excitation wavelengths as well as in an aqueous environment. To validate the increased sensitivity, I conducted an analysis using bovine serum albumin (BSA). This protein is water-soluble and has an infrared absorption band (amide I), and it is also active in the Raman region. Moreover, it can consistently bind to Ag features. Through an image-based analysis, the surface-enhanced Raman scattering pattern of the BSA was recorded. The proposed sensing method is innovative and opens new perspectives on sensitive methods for biomolecule detection. Simultaneously, it shows promising results to exploit the optical resonance shift as a basic sensing approach for probing molecular patterns.