Terahertz Metamaterial Sensors: Design Theory, Optimization Approach, and Advancements in Biosensing Applications

Metamaterials (MMs), distinguished by their unique electromagnetic properties, offer significant advantages in the realm of terahertz (THz) biosensing and early disease diagnosis. The intense electric field confined within subwavelength volumes in metallic MMs enhances the interaction between light and analytes. The Q-factor, sensitivity and figure of merit (FOM) are three critical direct parameters for quantitative evaluation of sensor performance. Researchers are pursuing enhancement of these parameters by optimal design of MMs structures and dimensions as well as proper choice of materials. Recently, dielectric perturbation theory is quantitatively calculated and successfully utilized in the design and optimization of THz MMs sensors. Guided by this theory, this review focuses on the design principle of THz MMs sensors, the various study on how to improve the fundamental parameters of THz MMs sensors, the specific application in biosensing including the functionalization process, and the fabrication of THz MMs sensors. Based on these methods and results, the future development of THz sensors is finally presented in a perspective view.