Highly Sensitive Tunable Dual-Band THz Refractive-Based Metamaterial Sensor for Biosensing Applications

A tunable dual-band terahertz (THz) dielectric-based metamaterial (MM) sensor that is highly sensitive and capable of detecting six different viruses is investigated in this article. The proposed absorber provides near-perfect absorption (Abs) at two narrow resonances, 3.659 and 4.656 THz, by using a circular ring resonator made of silicon and a square-shaped graphene (Gr) ring. The Gr's chemical potential can be modified to achieve tunability and controllability. The strong coupling between Gr and resonant structure results in high sensing parameters, such as a high $S$ of 3.29 and 3.28 THz/RIU, figure of merit (FOM) of 470.78 and 293.84 RIU $^{-1}$ , and $Q$ of 480 and 371.42 in the first and second bands, respectively. The proposed absorber's distinguishing features include its ultra-thin structure, polarization insensitivity, narrow Abs bandwidth, and high-quality factor. In addition, the absorber is unaffected by the input electromagnetic (EM) wave's polarization angle.