scholarly journals Volatile Gas Sensing through Terahertz Pipe Waveguide

Sensors ◽  
2020 ◽  
Vol 20 (21) ◽  
pp. 6268
Author(s):  
Ja-Yu Lu ◽  
Borwen You ◽  
Jiun-You Wang ◽  
Sheng-Syong Jhuo ◽  
Tun-Yao Hung ◽  
...  
Keyword(s):  
Dipole Moment ◽  
Strong Interaction ◽  
Reflectance Spectrum ◽  
Gas Sensing ◽  
Thz Radiation ◽  
Hollow Core ◽  
Label Free ◽  
Vapor Absorption ◽  
Gas Molecule ◽  
Volatile Liquids

Gas sensing to recognize volatile liquids is successfully conducted through pipe-guided terahertz (THz) radiation in a reflective and label-free manner. The hollow core of a pipe waveguide can efficiently deliver the sensing probe of the THz confined waveguide fields to any place where dangerous vapors exist. Target vapors that naturally diffuse from a sample site into the pipe core can be detected based on strong interaction between the probe and analyte. The power variation of the THz reflectance spectrum in response to various types and densities of vapors are characterized experimentally using a glass pipe. The most sensitive THz frequency of the pipe waveguide can recognize vapors with a resolution at a low part-per-million level. The investigation found that the sensitivity of the pipe-waveguide sensing scheme is dependent on the vapor absorption strength, which is strongly related to the molecular amount and properties including the dipole moment and mass of a gas molecule.

scholarly journals Collision-induced Spectra at a Gas-Solid Interface

1984 ◽  
Vol 37 (1) ◽  
pp. 63
Author(s):  
J Mahanty
Keyword(s):  
Dipole Moment ◽  
Time Dependence ◽  
Binary Mixtures ◽  
Optical Activity ◽  
Far Infrared ◽  
Inert Gases ◽  
Similar Process ◽  
Solid Interface ◽  
Gas Molecule ◽  
Typical Model

In analogy with collision-induced translational absorption in the far infrared in binary mixtures of inert gases, it is suggested that a similar process mustoccur at a gas-solid interface. Each gas molecule develops a dipole moment that depends on its distance from the surface, and its time dependence due to the thermal motion of the molecule should cause optical activity. The necessary theory and expected absorption curves for a typical model are given:

Gas-sensing performance of In2O3@MoO3 hollow core-shell nanospheres prepared by a two-step hydrothermal method

2021 ◽  
pp. 131007
Author(s):  
Haitao Fu ◽  
Xiaohong Yang ◽  
Zhenxiang Wu ◽  
Peng He ◽  
Shixian Xiong ◽  
...  
Keyword(s):  
Hydrothermal Method ◽  
Gas Sensing ◽  
Core Shell ◽  
Hollow Core ◽  
Sensing Performance

scholarly journals Application of a Terahertz System Combined with an X-Shaped Metamaterial Microfluidic Cartridge

Micromachines ◽  
2020 ◽  
Vol 11 (1) ◽  
pp. 74
Author(s):  
Shih-Ting Huang ◽  
Shen-Fu Hsu ◽  
Kai-Yuan Tang ◽  
Ta-Jen Yen ◽  
Da-Jeng Yao
Keyword(s):  
Far Infrared ◽  
Infrared Region ◽  
Microfluidic System ◽  
Electromagnetic Response ◽  
Thz Radiation ◽  
Similar Species ◽  
Label Free ◽  
Plasmonic Sensor ◽  
Molecular Fingerprint ◽  
Highly Sensitive Detection

Terahertz (THz) radiation has attracted wide attention for its ability to sense molecular structure and chemical matter because of a label-free molecular fingerprint and nondestructive properties. When it comes to molecular recognition with terahertz radiation, our attention goes first towards the absorption spectrum, which is beyond the far infrared region. To enhance the sensitivity for similar species, however, it is necessary to apply an artificially designed metamaterial sensor for detection, which confines an electromagnetic field in an extremely sub-wavelength space and hence receives an electromagnetic response through resonance. Once the resonance is caused through the interaction between the THz radiation and the metamaterial, a minute variation might be observed in the frequency domain. For a geometric structure of a metamaterial, a novel design called an X-shaped plasmonic sensor (XPS) can create a quadrupole resonance and lead to sensitivity greater than in the dipole mode. A microfluidic system is able to consume reagents in small volumes for detection, to diminish noise from the environment, and to concentrate the sample into detection spots. A microfluidic device integrated with an X-shaped plasmonic sensor might thus achieve an effective and highly sensitive detection cartridge. Our tests involved not only measurements of liquid samples, but also the performance of a dry bio-sample coated on an XPS.

scholarly journals Gas Sensing by Bacterial H-NOX Proteins: An MD Study

Molecules ◽  
2020 ◽  
Vol 25 (12) ◽  
pp. 2882 ◽  
Author(s):  
Ahmed M. Rozza ◽  
Dóra K. Menyhárd ◽  
Julianna Oláh
Keyword(s):  
Gas Sensing ◽  
Hydrophobic Interactions ◽  
Transport Systems ◽  
Alternative Mode ◽  
Channel System ◽  
Gas Molecule ◽  
O2 Diffusion ◽  
Dynamics Simulations ◽  
And Storage ◽  
Kinetics Of

Gas sensing is crucial for both prokaryotes and eukaryotes and is primarily performed by heme-based sensors, including H-NOX domains. These systems may provide a new, alternative mode for transporting gaseous molecules in higher organisms, but for the development of such systems, a detailed understanding of the ligand-binding properties is required. Here, we focused on ligand migration within the protein matrix: we performed molecular dynamics simulations on three bacterial (Ka, Ns and Cs) H-NOX proteins and studied the kinetics of CO, NO and O2 diffusion. We compared the response of the protein structure to the presence of ligands, diffusion rate constants, tunnel systems and storage pockets. We found that the rate constant for diffusion decreases in the O2 > NO > CO order in all proteins, and in the Ns > Ks > Cs order if single-gas is considered. Competition between gases seems to seriously influence the residential time of ligands spent in the distal pocket. The channel system is profoundly determined by the overall fold, but the sidechain pattern has a significant role in blocking certain channels by hydrophobic interactions between bulky groups, cation–π interactions or hydrogen bonding triads. The majority of storage pockets are determined by local sidechain composition, although certain functional cavities, such as the distal and proximal pockets are found in all systems. A major guideline for the design of gas transport systems is the need to chemically bind the gas molecule to the protein, possibly joining several proteins with several heme groups together.

scholarly journals Antiresonant Hollow-Core Fiber-Based Dual Gas Sensor for Detection of Methane and Carbon Dioxide in the Near- and Mid-Infrared Regions

Sensors ◽  
2020 ◽  
Vol 20 (14) ◽  
pp. 3813 ◽  
Author(s):  
Piotr Jaworski ◽  
Paweł Kozioł ◽  
Karol Krzempek ◽  
Dakun Wu ◽  
Fei Yu ◽  
...  
Keyword(s):  
Carbon Dioxide ◽  
Gas Sensor ◽  
Gas Sensing ◽  
Simultaneous Detection ◽  
Hollow Core ◽  
Mid Infrared ◽  
Sensing Applications ◽  
Core Fiber ◽  
Sensor Configuration ◽  
Carbon Dioxide Co2

In this work, we present for the first time a laser-based dual gas sensor utilizing a silica-based Antiresonant Hollow-Core Fiber (ARHCF) operating in the Near- and Mid-Infrared spectral region. A 1-m-long fiber with an 84-µm diameter air-core was implemented as a low-volume absorption cell in a sensor configuration utilizing the simple and well-known Wavelength Modulation Spectroscopy (WMS) method. The fiber was filled with a mixture of methane (CH4) and carbon dioxide (CO2), and a simultaneous detection of both gases was demonstrated targeting their transitions at 3.334 µm and 1.574 µm, respectively. Due to excellent guidance properties of the fiber and low background noise, the proposed sensor reached a detection limit down to 24 parts-per-billion by volume for CH4 and 144 parts-per-million by volume for CO2. The obtained results confirm the suitability of ARHCF for efficient use in gas sensing applications for over a broad spectral range. Thanks to the demonstrated low loss, such fibers with lengths of over one meter can be used for increasing the laser-gas molecules interaction path, substituting bulk optics-based multipass cells, while delivering required flexibility, compactness, reliability and enhancement in the sensor’s sensitivity.

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