High Sensitive Metasurface Absorber for Refractive Index Sensing

Metasurface absorber-based terahertz biosensors are one of the emerging fields for sensing devices because of their quick response to changes in the background refractive index, small size, easier fabrication and measurement. In this article, a simple design and highly sensitive metasurface absorber is presented for the detection of the change in background refractive index. The proposed device provides maximum sensitivity of 2.37 THz/RIU, Q-factor of 574.46, and FOM of 540 RIU
⁻¹
for the refractive index ranges from 1.0 to 1.37. The meta-atom consists of a bow-tie metallic patch that exhibits dual-band absorptance at 1.93 THz and 2.7 THz for the x-polarized incident wave. The surface resonances at 2.7 THz result in narrow bandwidth with a very high Q-factor which enable the sensing ability of the proposed device. The sensing performance of the proposed metasurface is demonstrated by detecting the tuberculosis bacteria in the blood sample. The extremely good traits of the proposed metasurface absorber-based sensor can be utilized to detect other viruses and bacteria present in the blood cells for diagnosis applications.