Terahertz Biochemical Molecule‐Specific Sensors

Abstract

The terahertz (THz) spectrum is the focus of basic research in solid‐state physics, chemistry, and materials science as well as applications in next‐generation communications, far‐infrared bolometer, bio/chemical‐sensing, and medical imaging. This wavelength range is at the intersection between photonics and electronics, presenting tremendous opportunities to boost fundamental light–matter interactions enabled by plasmonic nanostructures, metamaterials, and inherent molecular vibrational modes, which occur on time scales of tens of femtoseconds to picoseconds. Recently, engineered metamaterials have presented unique platforms for sensing applications due to their ability to boost such light–matter interactions on the nanoscale and to their spectral selectivity in a wide range from the mid‐infrared to the THz region. Their resonant response can be tuned to that of the intra‐ and intermolecular vibrational modes of target bio/chemical molecules. The emerging fields of highly sensitive and selective mid‐infrared and THz spectroscopies based on metamaterials and plasmonic nanostructures are reviewed. Furthermore, practical applications of these next generation spectroscopic sensors are also discussed, where the sensor platforms will lead to a great impact in the advancement of ultrasmall‐quantity detection of explosives, nondestructive inspection of hazardous materials, food safety, and conformational dynamics of biomolecules in their aqueous environment.

A THz graphene metasurface for polarization selective virus sensing

“…Virus analytes consists of antibody or bioreceptor proteins that selectively binds with target antigen or virus [ 5 , 9 ]. Conventionally, the small absorption cross section and nearly identical optical properties make viruses difficult to discriminate using traditional optical spectroscopic techniques.…”

“…Conventional optical spectroscopic methods for virus identification rely on the use of fluorescent materials such as dyes to label the target biomolecules [ 5 , 3 , 6 , 7 , 8 ]. Lately, immunoassay based on localized surface plasmon resonances (LSPR) has been introduced to improve detection limit at nanoscale for both solution and substrate based metallic nanoparticles [ 2 , 9 ].…”

Materials for Terahertz Optical Science and Technology

“…In the works discussed in Z. Ren et al, [12] and Y.-G. Jeong et al, [13] various devices based on microelectromechanical structures (MEMS) and vanadium dioxide (VO 2 ) interfaced tunable metamaterials are shown to actively modulate the THz waves through electrical/thermal controls. [16] A different class of low-loss metasurfaces fabricated with dielectric materials (see the review by R. T. Ako et al [17] ) with appropriate geometry can assist in sharp guided mode resonances with extremely high quality (Q)-factors (see the work by S. Han et al [18] ). Interfacing the graphene layer with metamaterials also enables an efficient modulation of resonant THz waves through voltage control (see the work on graphene metasurfaces from X. Chen et al [14] ).…”

“…The strong THz resonances with the combination of dielectric engineering in metamaterials enable sensitive molecule-specific detection capabilities by enhancing the resonant vibrational/ absorption peaks of the target bio/chemical molecules or any material systems, as reported in M. Seo and H.-R. Park. [16] A different class of low-loss metasurfaces fabricated with dielectric materials (see the review by R. T. Ako et al [17] ) with appropriate geometry can assist in sharp guided mode resonances with extremely high quality (Q)-factors (see the work by S. Han et al [18] ). Whispering gallery mode (WGM) resonators offer another exotic platform to realize high Q-factor resonances at THz frequencies that enable capabilities for single molecule sensing with high specificity for medical, chemical and security applications, as discussed in the works reviewed by S. S. Prabhu and V. G. Achantha.…”

Ultrasensitive detection of saccharides using terahertz sensor based on metallic nano-slits

“…In particular, inter-and intramolecular vibrations of biochemical molecules occur in the THz regime, and thus these molecules exhibit unique fingerprint features in this regime. Consequently, THz technology has unique advantages in biochemical sensing 1,2 . The emergence of various artificial materials raises the possibility of highly sensitive molecular fingerprint detection using THz spectroscopy 3,4 .…”