Sensitivity enhanced terahertz plasmonic metasurface biosensor based on symmetrical graphene–gold–silver resonators for breast cancer biomarker detection

Breast Cancer continues to be one of the top causes of death due to cancers in women around the world, therefore there is a significant need for new methods for detecting early stage breast cancer which are non-invasive. Conventional methods of diagnosing breast cancer, such as mammography and biopsy have their own limitations which includes invasiveness, ionizing radiation exposure and limited ability to detect small or early-stage tumors. This study proposes a new method for detecting breast cancer using a Terahertz (THz) Metamaterial Biosensor that includes Graphene, Gold (Au), Silver (Ag), Copper (Cu) Nano-Structures which can selectively and sensitively detect biomarkers for breast cancer by measuring the refractive index changes of the material. The Sensor Architecture has a hierarchical structure consisting of nested resonators (Circular Au Rings, Rectangular Ag Resonators, and Square Cu Rings) which are located on a Graphene-Coated Glass Substrate and were optimized to create Surface Plasmon Resonance (SPR) and EM Field Confinement in the THz Regime. Machine Learning and Simulation Results indicate that the proposed sensor achieves a sensitivity of 500 GHz/RIU and Figure of Merit (FOM) values ranging from 1.744 to 4.202 RIU⁻ 1 and detection limits below 1.01 RIU. The sensor’s absorption and resonance responses can be modified via changing graphene’s chemical potential (0.1 – 0.9 eV), incidence angle (0° – 80°), and resonator geometry (Square Ring Side Length 4.6 – 9.6 µm). Peak absorption was found to be 57.518% at 0.9 eV. An XGBoost machine learning model was used to determine the best possible performance predictions based on refractive index, incidence angle, and resonator size variation for which the R2 > 0.9997 was attained. This integration of plasmonic metasurface design and machine learning provides a robust, highly precise design for early breast cancer detection with potential clinical translation and supporting the objectives of Sustainable Development Goal 3 (SDG 3): Good Health and Well-Being by promoting early diagnosis and improved healthcare outcomes.