Angularly Stable High-Q Factor Metamaterial Absorber for Biomedical Sensing Applications

In this letter, a thin, high Q-factor, angularly stable, and polarization-insensitive metamaterial absorber (MMA) for sensing applications is presented. The absorber operates at the C-band, having near-unity absorptivity. The symmetric design is polarization-insensitive under normal incidence. In addition, the novel design shows more than 90% absorptivity, up to 80° incident angle, for both transverse electric and transverse magnetic polarized waves under oblique incidence. The absorption mechanism is described with the help of surface current distribution, induced electric field, and parametric analysis. To verify the resonance characteristic of the structure, an equivalent circuit analysis has been presented. A precise shift in the absorption frequency is observed in response to alteration in the permittivity value of a material placed above the geometry; hence, the proposed structure can be used as a refractive index sensor. Multiple characteristics, such as thin profile, high angular stability, polarization insensitiveness, and high Q factor, make the proposed MMA highly desirable in refractive index sensing for biomedical applications.