Design and optimization of highly sensitive multi-band terahertz metamaterial biosensor for coronaviruses detection.

This study presents the design and characterization of a highly Q-Factor and ultrasensitive THz refractive-index-based metamaterial biosensor for detecting coronaviruses at electronic infusion device (EID) concentrations 0.01 and 1000. The proposed biosensor is constructed using a gold plane perforated by a star shape. Moreover, the developed structure is polarization insensitive due to the rotatory symmetry and is angularly stable up to 90°. The proposed biosensor achieves near-perfect absorption at 1.9656 THz and 3.3692 THz. The full width at half-maximum is 5.276% and 0.641% comparative to the absorption frequency. In addition, the estimated free space absorptivity is 97.2% and 99.1% with a Q-Factor of 19.08 and 155.98 at 1.9656 THz and 3.3692 THz, respectively, when transverse electromagnetic mode (TEM) was selected. The perforated star-shaped was evaluated for IBV (Family of COVID-19) regarding frequency deviation, sensitivity, and figure of merit. Results show that at 1.9656 THz, the proposed design gives 30.8 GHz, 940.49 GHz/RIU, and 8.6, respectively, for 0.01 (EID/5 µL concentration) and 4.4 GHz, 2200 × 103 GHz/RIU, and 20,215.014, respectively at 1.9612 THz for 1000 (EID/5 µL concentration). Although the obtained results demonstrate the efficiency of the proposed THz metamaterial biosensor in coronavirus detection, it has also been extended for other types of viruses, including H5N1, H5N2, H9N2, H4N6, and FAdV, based on the slight variations in their refractive indices. Additionally, the influence of the design parameters is optimized in order to achieve better performance.