Oblique and Polarization Independent Metasurface-Based Absorber for Bio-Sensing Applications

In this paper, a submillimetric/THz metasurface polarization/oblique independent absorber is designed and characterized. The absorber is designed using a periodic arrangement of a modified split ring resonator unit cell. The symmetric absorber is insensitive to the variation of incident angles and polarization angles. The results confirm that perfect absorption is achieved (close to 100%) for either TM or TE polarization at 300 GHz. Moreover, the absorber is efficient for normal and oblique incident angle (above 90% for 45 degrees angle of incidence). In all the presented cases, the full width half maximum bandwidth is 20 GHz. The absorber unit cell size is only 0.0052 lambda(0) x 0.0052 lambda(0) and it has a low-profile thickness = 0.0002 lambda(0), at the operating frequency. Also, an absorber-based biosensor is presented. The sensing has proved the coating analyte thickness can be detected by shifting the absorption frequency. The maximum sensitivity is 24.9% RIU-1 with a low-profile maximum of 50 mu m thickness. Analytical formulas for the frequency shift have been extracted. The presented results are discussed based on 3D full-wave EM simulations.