enhancement of figure of merit and spectral sensitivity in a hyperbolic metamaterial optical biosensor utilizing a graphene nanograting

Faraji, Heidar; Haji-nasiri, Saeed; Andalibi Miandoab, Shabnam

doi:10.22075/jme.2026.39654.2933

enhancement of figure of merit and spectral sensitivity in a hyperbolic metamaterial optical biosensor utilizing a graphene nanograting

Articles in Press

Document Type : Research Paper

Authors

Heidar Faraji ¹

saeed haji-nasiri ²

Shabnam Andalibi Miandoab ³

¹ Department of Electrical Engineering, Qa.C., Islamic Azad University, Qazvin, Iran

² Faculty of Electrical, Biomedical and Mechatronics Engineering, Qazvin Branch, Islamic Azad University, Qazvin, Iran

³ Department of Electrical Engineering, Ta.C., Islamic Azad University, Tabriz, Iran

10.22075/jme.2026.39654.2933

Abstract

In this study, a novel plasmonic biosensor structure based on a graphene microstrip grating and a hyperbolic metamaterial (HMM) composed of alternating layers of graphene and Al₂O₃ is proposed. In this design, the graphene microstrip grating serves as the main substrate for coupling electromagnetic waves and generating a strong plasmonic field. The placement of the hyperbolic metamaterial on top of the graphene further enhances the optical fields with large wave vectors and improves field confinement, resulting in a significant increase in the sensor’s sensitivity (S) and figure of merit (FOM). The effective medium theory is employed to determine the constitutive parameters of the metamaterial. Using the finite-difference time-domain (FDTD) method, the reflection spectra and resonance damping characteristics are investigated under variations of structural parameters and graphene Fermi energy levels. The simulation results demonstrate that the proposed biosensor achieves a sensitivity of 3412 nm·RIU⁻¹ and a figure of merit (FOM) of 29.66 RIU⁻¹, confirming its strong potential for selective and ultra-sensitive biomolecular detection.

Keywords

Optical biosensor

graphene

Hyperbolic etamaterials

FDTD

surface plasmon

Subjects