<p>This theoretical and numerical work presents a graphene-enabled metamaterial refractive-index sensor concept for terahertz (THz) biosensing, aimed at exploring routes toward early-stage screening of biological agents. The proposed metasurface employs a dual elliptical-ring resonator designed to maintain stable operation under different polarization states while enabling bidirectional resonance tuning. The sensing mechanism is studied using numerical full-wave electromagnetic simulations and supported by theoretical interpretation of the resonance physics through field distributions and surface-current responses. When an analyte layer is introduced, a pronounced resonant absorption feature is obtained in simulation, and the resonance position is shown to be governed primarily by the analyte dielectric response. This behavior enables spectral discrimination among representative dielectric models of biosensing targets, including bacterial samples and malignant-cell analogs. Reconfigurability is investigated through two complementary strategies: (i) tuning the graphene chemical potential to strengthen near-field confinement and enhance simulated refractive-index sensitivity, and (ii) introducing a molybdenum disulfide (MoS₂) layer to shift the operating band and expand the accessible tuning range. Simulated field maps and current distributions corroborate the resonance behavior and indicate robust sensing characteristics under the studied conditions. Overall, the results numerically suggest that the proposed architecture could serve as a promising platform for THz biosensing and spectroscopy, motivating future experimental validation.</p>