A comparative analysis of plasmonic and dielectric metasurface sensing platforms powered by bound states in the continuum

TL;DR

This paper compares plasmonic and dielectric metasurface sensors driven by bound states in the continuum for molecular detection, highlighting their performance differences in various liquid environments and guiding optimal platform selection.

Contribution

It provides a systematic evaluation of plasmonic and dielectric BIC metasurfaces in liquid environments, revealing their respective advantages and crossover points for sensing applications.

Findings

Dielectric metasurfaces perform better in dry conditions.

Plasmonic metasurfaces outperform in lossy solvents.

A crossover point exists where both platforms have similar performance.

Abstract

Nanophotonic platforms based on surface-enhanced infrared absorbance spectroscopy (SEIRAS) have emerged as an effective tool for molecular detection. Sensitive nanophotonic sensors with robust resonant modes and amplified electromagnetic near fields are essential for spectroscopy, especially in lossy environments. Metasurfaces driven by bound state in the continuum (BICs) have unlocked a powerful platform for molecular detection due to their exceptional spectral selectivity. While plasmonic BIC metasurfaces are preferred for molecular spectroscopy due to their high surface fields, enhancing the interaction with analytes, dielectric BICs have become popular due to their high-quality factors and, thus high sensitivity. However, their sensing performance has largely been demonstrated in air, neglecting the intrinsic infrared (IR) losses found in common solvents. This study evaluates the suitability of plasmonic versus dielectric platforms for in-situ molecular spectroscopy. Here, the sensing performance of plasmonic (gold) and dielectric (silicon) metasurfaces is assessed across liquid environments with varying losses resembling typical solvents. The results show that dielectric metasurfaces excel in dry conditions, while plasmonic BIC metasurfaces outperform them in lossy solvents, with a distinct crossover point where both show similar performance. Our results provide a framework for selecting the optimal metasurface material platform for SEIRAS studies based on environmental conditions.