Development of a High-Sensitivity Multimode Graphene-Based Metamaterial Biosensor with a Double-Split Elliptical Resonator for Refractive Index Sensing and Biomedical Applications

This paper presents a high-sensitivity, multimode graphene-based metamaterial (MM) biosensor for refractive index sensing, utilizing a periodic array of gold (Au) double-split elliptical resonators (DSERs) on a graphene-coated silicon dioxide (SiO₂) substrate with an Au base layer. Finite-difference time-domain (FDTD) simulations confirm that the double-split elliptical design enhances field confinement and supports the excitation of multiple distinct resonance modes, offering an improvement over traditional circular or rectangular resonators. The sensor operates within the 650–1500 nm reflection range, supporting five distinct resonance modes that provide multiple sensing pathways, thereby improving detection efficiency compared to standard single-mode plasmonic sensors. Optimal performance is achieved by precisely tuning critical structural parameters, such as the thickness of the gold array and the SiO₂ layer, as well as the resonator width. According to the results, the proposed design is sensitive to the surrounding medium and can be used as a refractive index sensor. This sensing mechanism can be applied in a wide range of biomedical applications, including the differentiation between normal and cancerous cells. In the proposed design, three types of cancerous cells (basal, breast, and cervical) are used as test samples to evaluate the biosensor’s performance. The results show that the biosensor outperforms many existing designs reported in the literature. Specifically, for breast cancer cells, it achieves a maximum sensitivity of 714.28 nm/RIU, a figure of merit (FoM) of 51.02 1/RIU, and a quality factor (QF) of 73.42. These findings highlight the potential of the proposed biosensor as a promising candidate for future optical sensing technologies, advanced medical diagnostics, and a wide range of biomedical applications.