Numerical Analysis of a High-Sensitivity Graphene-Based SPR Biosensor With a Split Elliptical Metamaterial Resonator for Hemoglobin Detection

This study presents a high-sensitivity graphene-based surface plasmon resonance (SPR) biosensor for hemoglobin detection, introducing a novel integration of a gold arc-shaped resonator (ASR) with a split elliptical-shaped resonator (SESR) on a graphene-coated silicon dioxide (SiO2) substrate. Unlike traditional circular or rectangular resonators, the use of a divided elliptical geometry enhances field confinement. It enables the excitation of multiple distinct resonance modes, confirmed through finite-difference time-domain (FDTD) simulations. The sensor structure supports three prominent resonance modes within the 800–1800 nm reflection spectrum, offering multiple sensing channels and improved detection capabilities over conventional single-mode plasmonic sensors. Key geometric parameters, including the gold array thickness, resonator width, and SiO2 layer thickness, are systematically optimized to maximize performance. Notably, mode 1 achieves a high sensitivity of 500 nm/RIU for hemoglobin refractive indices ranging from 1.36 to 1.39 ( $\Delta {n} =0.03$ RIU), with a figure of merit (FoM) of 41.66 1/RIU and a quality factor (QF) of 99.75. Mode 3 also demonstrates strong sensing potential, with 450 nm/RIU sensitivity, a FoM of 37.7 1/RIU, and a QF of 72.75. The incorporation of monolayer graphene further enhances plasmon-field coupling and tunability, offering significant improvements in detection sensitivity and fabrication feasibility. These results highlight the effectiveness and practical applicability of the proposed biosensor for advanced medical diagnostics and biomolecular sensing, marking a substantial advancement over previous SPR-based sensor designs.