Recent Developments in Terahertz Nanosensors

Terahertz (THz) waves occupy the electromagnetic spectrum between microwave and infrared radiation, with frequencies typically ranging from 0.1 to 10 THz. Compared with other optic and electronic tools, this frequency range allows for unique sensing applications such as nondestructive, label-free, and fast detection. Despite the promising features of THz sensing applications, the dimensional mismatch between THz wavelength and nanoscale agents hinders practical applications, especially in biosensing and chemical sensing. Several recent studies propose that engineered THz resonators, such as split ring resonators, linear dipole and slot antennas, and nanogap loop antennas, enhance the sensitivity for detecting trace amounts of target molecules, such as viruses and explosives. When combined with near-field imaging techniques in the THz range, these THz nanosensors may revolutionize our understanding of complex nanoscale systems, including 2D materials, as researchers can observe quantum dynamics directly in molecules, mobile carriers in semiconductors, THz quantum nonlocal effects, and dynamics of excitons and polaritons at THz frequencies. Additionally, THz biomolecular sensors are also discussed, where the sensor platforms will lead to a great impact in the advancement of ultrasmall-quantity characterization of proteins, label-free diagnosis of Alzheimer's disease, and conformational dynamics of biomolecules in their aqueous environment. Based on metal nanoresonators, this review presents fundamental principles of sensing materials using terahertz electromagnetic waves, as well as recent applications of terahertz near- and far-field sensing. This sensor platform will lead to a great impact on the advancement of ultrasmall quantity characterization of biological and chemical molecules in terahertz frequency regions.image (c) 2023 WILEY-VCH GmbH