Ultra-sensitive wide-angle and polarization-independent terahertz metamaterial absorbers for early detection of basal cell carcinoma

Abstract Terahertz metamaterial absorbers have come to the forefront of biosensing applications due to the non-ionizing characteristics and sensitivity to weak interactions of the terahertz radiation. This article presents a novel design of graphene-based terahertz metasurface absorber (MSA) aimed at early label-free cancerous cell detection. The design consists of two concentric hexagonal graphene rings placed on top of a SiO 2 dielectric layer, followed by a gold metallic ground plane. We achieve a near-perfect absorption of 97% at 3.275 THz with a Q-factor of 22.061. The simulated spectral characteristics are verified analytically using the impedance matching theory. A near-perfect absorption at the resonant frequency can be attributed to the effective excitation of localized surface plasmon modes. The proposed biosensor demonstrates a sensitivity of 0.622 THz RIU −1 , and a figure of merit (FoM) of 4.49 RIU −1 in response to the normal cell. On the contrary, it shows a sensitivity of 0.626 THz RIU −1 , and a FoM of 4.42 RIU −1 in response to the basal carcinoma cells. A parametric study of the thickness and refractive index of the analyte suggests that the proposed design may be applied to the detection of thin films of biological samples. Furthermore, the effect of changes in the chemical potential and relaxation time of Graphene is also investigated. The MSA is polarization-independent and shows wide incident angle stability (up to 60°). The sensitivity and FoM calculations suggest that the proposed MSA can outperform recently reported biosensors, potentially leading to a significant improvement in diagnostic accuracy for early-stage cancer detection.