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<p>This paper proposes a six-band graphene-based terahertz biosensor for label-free, multiplexed detection of biomaterials in the 2–7&#xa0;THz range. It consists of interdigitated graphene strips on a Topas substrate with a gold ground plane, achieving absorption (&gt; 94%) at resonance peaks (2.605, 3.223, 3.938, 4.458, 5.156, and 5.839&#xa0;THz) through progressive resonant coupling. Parametric analysis reveals high angular stability (absorption &gt; 80% up to θ<sub>inc</sub> = 75° oblique incidence) with graphene of (μ<sub>c</sub> = 0.8&#xa0;eV and τ = 3.0&#xa0;ps), optimizing Q-factors above 30. The biosensor exhibits good polarization robustness for φ<sub>inc</sub> ≤ 45° (absorption &gt; 95%), making it suitable for applications with controlled or partially polarized illumination. However, it shows sensitivity to higher polarization angles due to its anisotropic strip geometry. An accurate equivalent circuit model of cascaded parallel RLC resonators is optimized via particle swarm optimization (PSO) and matches simulation results within 1.5%. Refractive index sensing of analytes (n = 1–1.5) exhibits linear frequency shifts (R<sup>2</sup> &gt; 0.99) with sensitivities of 0.35–1.4&#xa0;THz/RIU across bands, with peak figure-of-merit reaching 12 RIU⁻<sup>1</sup>, enhanced by evanescent-field confinement visualized via 2D E-field distributions. For disease detection, the biosensor compares normal and cancerous tissues (cervical: Δf = 0.325&#xa0;THz, sensitivity = 679.2&#xa0;GHz/RIU; breast: 993.9&#xa0;GHz/RIU; basal: 1625&#xa0;GHz/RIU; blood: 812.5&#xa0;GHz/RIU) via distinct shifts (Δn = 0.01–0.04). Virus sensing yields band-specific fingerprints for six pathogens (Malaria, HSV, Influenza, HIV, Corona, M13), with Δf up to 487.5&#xa0;GHz, sensitivities 317–855&#xa0;GHz/RIU, and Q-factors 26–37. These simulated findings offer potential applications for reagent-free multiplexed detection in clinical diagnostics.</p>

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Tunable multi-band graphene-based terahertz absorber for high-sensitivity multiplexed biosensing

  • 期刊论文

  • 发表日期：

    2026年3月7日

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  • Hend Malhat,
  • Amer Zakaria,
  • Nasser Qaddoumi

摘要

This paper proposes a six-band graphene-based terahertz biosensor for label-free, multiplexed detection of biomaterials in the 2–7 THz range. It consists of interdigitated graphene strips on a Topas substrate with a gold ground plane, achieving absorption (> 94%) at resonance peaks (2.605, 3.223, 3.938, 4.458, 5.156, and 5.839 THz) through progressive resonant coupling. Parametric analysis reveals high angular stability (absorption > 80% up to θinc = 75° oblique incidence) with graphene of (μc = 0.8 eV and τ = 3.0 ps), optimizing Q-factors above 30. The biosensor exhibits good polarization robustness for φinc ≤ 45° (absorption > 95%), making it suitable for applications with controlled or partially polarized illumination. However, it shows sensitivity to higher polarization angles due to its anisotropic strip geometry. An accurate equivalent circuit model of cascaded parallel RLC resonators is optimized via particle swarm optimization (PSO) and matches simulation results within 1.5%. Refractive index sensing of analytes (n = 1–1.5) exhibits linear frequency shifts (R2 > 0.99) with sensitivities of 0.35–1.4 THz/RIU across bands, with peak figure-of-merit reaching 12 RIU⁻1, enhanced by evanescent-field confinement visualized via 2D E-field distributions. For disease detection, the biosensor compares normal and cancerous tissues (cervical: Δf = 0.325 THz, sensitivity = 679.2 GHz/RIU; breast: 993.9 GHz/RIU; basal: 1625 GHz/RIU; blood: 812.5 GHz/RIU) via distinct shifts (Δn = 0.01–0.04). Virus sensing yields band-specific fingerprints for six pathogens (Malaria, HSV, Influenza, HIV, Corona, M13), with Δf up to 487.5 GHz, sensitivities 317–855 GHz/RIU, and Q-factors 26–37. These simulated findings offer potential applications for reagent-free multiplexed detection in clinical diagnostics.