Investigations on a Triple-Band Metasurface Absorber as THz-Biomedical Sensor

Abstract

This article describes a highly sensitive sensor based on a tunable triple-band metasurface absorber that can detect and classify six types of cancer. Meta-atom of the metasurface is designed using truncated square patch enclosed within split circular ring. It has compact footprint and low profile of $0.24\lambda \times 0.24\lambda \times 0.01\lambda $ with absorbance peaks around 2.5, 4.7, and 8.7 THz. Full-wave electromagnetic simulations show that it can achieve theoretical absorption in excess of 99% as a result of multipoint impedance matching and surface plasmon resonance (SPR). Moreover, it features high quality factors, which is essential for sensing-allied applications. Consequently, the suggested absorber is applied in sensing of refractive index (RI) and thickness of an analyte. The sensor exhibits sensitivity of around 0.89, 4.79, and 4.57 THz/RIU when the RI of 2- $\mu $ m-thick analyte varies from 1.34 to 1.40 with a resolution of 0.01 in the three absorption bands. Also in the corresponding bands, it provides sensitivity of approximately 0.05, 0.16, and 0.24 THz/ $\mu $ m at an RI of 1.37 in the analysis of analyte thickness. The peak sensitivity of 4.70, 5.50, 5.67, 4.50, 4.78, and 5.05 THz/RIU is obtained for blood, basal, cervical, jurkat, breast, and MCF-7 cancers, respectively, with extremely high figure of merits of 16.26, 19.16, 19.68, 12.85, 16.26, and 17.12 RIU-1. Given these metrics, the proposed design has the potential to be used a THz-biomedical sensor.