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

Abstract

Unambiguous identification of trace amounts of biochemical molecules in a complex background using terahertz spectroscopy is extremely challenging owing to the extremely small absorption cross sections of these molecules in the terahertz regime. Herein, we numerically propose a terahertz nonresonant nano-slits structure that serves as a powerful sensor. The structure exhibits strongly enhanced electric field in the slits (five orders of magnitude), as well as high transmittance over an extra-wide frequency range that covers the characteristic frequencies of most molecules. Fingerprint features of lactose and maltose are clearly detected using this slits structure, indicating that this structure can be used to identify different saccharides without changing its geometrical parameters. The absorption signal strengths of lactose and maltose with a thickness of 200 nm are strongly enhanced by factors of 52.5 and 33.4, respectively. This structure is very sensitive to thin thickness and is suitable for the detection of trace sample, and the lactose thickness can be predicted on the basis of absorption signal strength when the thickness is less than 250 nm. The detection of a mixture of lactose and maltose indicates that this structure can also achieve multi-sensing which is very difficult to realize by using the resonant structures.

Design and assembly of porous organic cages

“…This granularity in design ensures that gas molecules can be selectively separated with a high degree of precision. Selective adsorption by organic cages has been demonstrated for a number of gas pairs including CO 2 /CH 4 , 19,141,142 CO 2 /N 2 , [142][143][144] Xe/Kr, 115,145 and H 2 /D 2 . 146 Removing CO 2 from the atmosphere or other gases may be one of the last viable ways to mitigate catastrophic climate change.…”

“…Many studies have reported the ideal selectivity in gas pairs of CO 2 /N 2 or CO 2 /CH 4 achieved by POCs. 19,[141][142][143][144] The size of the cage interior in POCs is tailored by selecting appropriate precursors and employing post-synthetic modification strategies, consequently facilitating selective adsorption by precisely differentiating the size among various gas molecules. Also, the introduction of specific functional groups into the cage structure can enhance its capacity for CO 2 adsorption.…”

Enhancing Multi-Spectral Fingerprint Sensing for Trace Explosive Molecules with All-Silicon Metasurfaces

“…Therefore, a large quantity of samples is needed to observe significant fingerprint absorption signals [8][9][10][11]. In the past few years, to enhance the detection sensitivity and achieve the identification of trace analytes, metasurface structures have been introduced, such as metal gratings, split-ring resonators, dielectric metasurfaces, nano-antenna arrays, and waveguide structures [12][13][14][15][16][17][18][19][20][21]. These additional structures aim to amplify the electromagnetic interaction between the electromagnetic waves and analyte samples, thereby magnifying the fingerprint absorption of the analytes.…”

Terahertz Fingerprint Metasurface Sensor Based on Temperature Variation for Trace Molecules

“…In previous studies, researchers have proposed various artificially designed metasurface structures, including open-ring resonators [11], metal gratings [12], photonic crystal structures [13], waveguide configurations [14], and structures based on bound states in the continuum [15,16], to achieve heightened sensitivity in material detection [17][18][19]. The majority of these structures are limited to detecting material absorption characteristics at individual frequency points via resonance peaks.…”