Terahertz biosensor for amino acids upon all-dielectric metasurfaces with high-quality factor

Due to their high sensitivity, nondestructive nature, exceptional penetration, and low energy, terahertz waves have significant potential in biosensing. Recently, metasurfaces with excellent electromagnetic properties have propelled the investigation of terahertz sensors. However, the predominant focus in previous studies lay on low-mode conditions characterized by inferior quality factors, thereby hindering expansive progress and implementation at a larger scale. Therefore, a terahertz biosensor for amino acids predicated on dielectric metasurfaces characterized by high- and high-quality factors is proposed. The single-sphere metasurface exhibited a high-quality factor and superior refractive index sensing characteristics. To improve the stability and reliability of the sensor, we designed a biosensor with a dual-sphere structure, achieving a quality factor of 451.88, a figure of merit of 42.2, and a sensitivity of 135 GHz/RIU. It not only demonstrates exceptional performance but also presents advantages and novel perspectives for the advancement of terahertz biosensor technology. When terahertz electromagnetic waves are incident on the biosensor we designed, biological molecule solutions of different concentrations will cause the absorption peak of the sensor to shift. We can distinguish amino acid solutions with different refractive indices by the change in the position of the absorption peak.