Plasmon-Enhanced Refractive Index Sensing of Biomolecules Based on Metal–Dielectric–Metal Metasurface in the Infrared Regime
Ghulam Abbas Khan, Yonghua Lü, Pei Wang
Abstract
High Resolution Image Download MS PowerPoint Slide Infrared plasmonic sensors offer enhanced biomolecule detection potential over visible sensors due to unique spectral fingerprints, enhanced sensitivity, lower interference, and label-free, nondestructive analysis capabilities. Moreover, multimode plasmonic sensors are highly advantageous for their ability to outperform single-mode counterparts through long-wavelength tuning, enhanced information retrieval, and reduced false results through multimode data cross-referencing. In this study, to achieve a high quality factor and enhanced sensitivity simultaneously, we employed silver square block arrays (SSBs) in a metal–dielectric–metal configuration. The proposed design supports three modes resulting from gap plasmons and propagating surface plasmon resonances, enabling the detection of a broad spectrum of biomolecules. Designed sensors demonstrate notable sensitivities in different modes: Mode I achieves 525 nm/RIU, Mode II reaches 1287 nm/RIU, and Mode III records 812 nm/RIU, while maintaining the quality factor of Mode I─17, Mode II─356, and Mode III─107. The figure of merit for Mode I is 7 RIU –1, for Mode II it is 375 RIU –1, and for Mode III it is 98 RIU –1 . Different concentrations of glucose and hemoglobin are efficiently detected with the proposed sensor, showing great potential for its biosensing application and real-time monitoring of biomolecule dynamics. Taken together, the proposed sensor exhibits the capability to identify diverse types of biomolecules and holds the potential to serve as a preliminary screening tool for various biomolecules.