Recent Progress in Novel Terahertz Metamaterial Sensors: A Review

The development and utilization of terahertz (THz) bands have aroused great interest worldwide. Some molecules and biomolecules exhibit unique fingerprint characteristics within the THz band, indicating that the THz technology can be effectively applied in the sensing field. However, natural materials that respond adequately to THz wavelengths are expensive and scarce, which limits the further development of THz technology. In recent years, periodic man-made electromagnetic metamaterials have been used to replace natural materials in the fabrication of THz devices, and have attracted great interest among domestic and foreign scientific researchers. These metamaterials not only show local electric field enhancement and high quality factor (<italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">Q</i>) values but are also extremely sensitive to tiny changes in the dielectric constant of the external environment, opening up new possibilities for the application of THz technology. In this paper, the sensing mechanism and characteristic parameters of the terahertz metamaterial sensor (TMS) are introduced, the new progress of TMS technology is summarized and discussed, and the development trends and challenges of the application of TMS are discussed.