Tunable terahertz biosensing and shielding using a graphene-enhanced dielectric resonator absorber

In this paper, we present a compact terahertz (THz) absorber based on a graphene-enhanced dielectric resonator structure, designed to achieve both wideband and narrowband absorption. The proposed absorber demonstrates ultra-wideband absorption from 1.07 to 13.3 THz, achieving a bandwidth of 12.23 THz, along with a sharp narrowband peak at 6.81 THz under specific tuning conditions. Tunability is achieved by adjusting the chemical potential (µc) of graphene, while the structure remains polarization-insensitive and maintains high absorption stability up to incident angles of 70°. Simulation results validated through an equivalent circuit model demonstrate the absorber's strong performance with a maximum sensitivity (S) of 5.11 THz/RIU, figure of merit (FOM) of 601.2 RIU^-1, and a quality factor (Q) of 1322.5, making it highly effective for biosensing applications, including the detection of chemicals, viruses, and cancerous cells. Additionally, for EM interference shielding, the absorber exhibits an absorption effectiveness exceeding 10 dB, and a reflectance effectiveness within 1 dB, confirming its high efficiency in suppressing reflected waves. These results highlight the absorber's potential for versatile applications in stealth, shielding, and practical biosensing.