scholarly journals Dual-comb Photothermal Spectroscopy

2021 ◽  
Author(s):  
Qiang Wang ◽  
Zhen Wang ◽  
Hui Zhang ◽  
Shoulin Jiang ◽  
Yingying Wang ◽  
...  
Keyword(s):  
Gas Sensing ◽  
Spectroscopic Method ◽  
High Sensitivity ◽  
Fast Response ◽  
Sample Volume ◽  
Small Sample ◽  
Probe Laser ◽  
Spectral Measurements ◽  
Photothermal Spectroscopy ◽  
Fine Resolution

Abstract Dual-comb spectroscopy (DCS) has revolutionized optical spectroscopy by providing broadband spectral measurements with unprecedent resolution and fast response. Photothermal spectroscopy (PTS) offers an ultrasensitive and background-free gas sensing method, which is normally performed using a single-wavelength pump laser. The merging of PTS with DCS may enable a new spectroscopic method by taking advantage of both technologies, which has never been studied yet. Here, we report dual-comb photothermal spectroscopy (DC-PTS) by passing dual combs and a probe laser through a gas-filled anti-resonant hollow-core fiber, where the generated multi-heterodyne modulation of the refractive index is sensitively detected by an in-line interferometer. As an example, we have measured photothermal spectra of acetylene over 1 THz, showing a good agreement with the spectral database. Our proposed DC-PTS provides new opportunities for broadband gas sensing with super-fine resolution and high sensitivity, as well as with a small sample volume and compact configuration.

scholarly journals MWCNT Devices Fabricated by Dielectrophoresis: Study of Their Electrical Behavior Related to Deposited Nanotube Amount for Gas Sensing Applications

2015 ◽  
Vol 10 (1) ◽  
pp. 13-20
Author(s):  
Elisabete Galeazzo ◽  
Marcos C. Moraes ◽  
Henrique E. M. Peres ◽  
Michel O. S. Dantas ◽  
Victor G. C. Lobo ◽  
...  
Keyword(s):  
Carbon Nanotubes ◽  
Gas Sensing ◽  
High Sensitivity ◽  
Cost Effective ◽  
Adsorbed Water ◽  
Fast Response ◽  
Process Time ◽  
Electrical Behavior ◽  
Glass Substrates ◽  
Sensing Applications

Intensive research has been focused on investigating new sensing materials, such as carbon nanotubes (CNT) because of their promising characteristics. However, there are challenges related to their application in commercial devices such as sensitivity, compatibility, and complexity of miniaturization, among others. We report the study of the electrical behavior of devices composed by multi-walled carbon nanotubes (MWCNT) deposited between aluminum electrodes on glass substrates by means of dielectrophoresis (DEP), which is a simple and cost-effective method. The devices were fabricated by varying the DEP process time. Remarkable changes in their electric resistance were noticed depending on the MWCNT quantities deposited. Other electrical properties of devices such as high sensitivity, fast response time and stability are also characterized in humid environment. A humidity sensing mechanism is proposed on the basis of charge transfer between adsorbed water molecules and the MWNTC surface or between water and the glass surface.

scholarly journals A Novel Type Room Temperature Surface Photovoltage Gas Sensor Device 

2018 ◽  
Author(s):  
Monika Kwoka ◽  
Michal A. Borysiewicz ◽  
Pawel Tomkiewicz ◽  
Anna Piotrowska ◽  
Jacek Szuber
Keyword(s):  
Gas Sensor ◽  
Room Temperature ◽  
Gas Sensing ◽  
Signal To Noise Ratio ◽  
High Sensitivity ◽  
Fast Response ◽  
Surface Photovoltage ◽  
Kelvin Probe ◽  
Sensor Device ◽  
Developed Surface

In this paper a novel type of a highly sensitive gas sensor device based on the surface photovoltage effect is described. The developed surface photovoltage gas sensor is based on a reverse Kelvin probe approach. As the active gas sensing electrode the porous ZnO nanostructured thin films are used deposited by the direct current (DC) reactive magnetron sputtering method exhibiting the nanocoral surface morphology combined with an evident surface nonstoichiometry related to the unintentional surface carbon and water vapor contaminations. Among others, the demonstrated SPV gas sensor device exhibits a high sensitivity of 1 ppm to NO2 with a signal to noise ratio of about 50 and a fast response time of several seconds under the room temperature conditions.

Effects of Preparing Conditions on NO2-Sensing Properties of Sputtered WO3 Nano-Films

2013 ◽  
Vol 690-693 ◽  
pp. 1680-1684
Author(s):  
Feng Yun Sun ◽  
Ming Hu ◽  
Peng Sun
Keyword(s):  
Gas Sensing ◽  
High Sensitivity ◽  
Fast Response ◽  
Optimal Parameters ◽  
Working Pressure ◽  
Sensing Properties ◽  
Dc Reactive Magnetron Sputtering ◽  
Experiment Method ◽  
Discharge Gas ◽  
Gas Ratio

WO3 nano-films were deposited on Al2O3 substrate by dc reactive magnetron sputtering method. The effects of preparing conditions, such as the discharge gas ratio (Ar:O2), working pressure, sputtering time and annealing temperature on microstructure, crystalline state and NO2-sensing properties of WO3 nano-films were investigated by orthogonal trial experiment method. The optimum technological conditions were determined by orthogonal test and extreme difference analysis. The crystallization, morphology and composition of WO3 thin film obtained at the optimal parameters were studied by XRD, SEM and XPS. The gas sensing mechanism was also studied. WO3 nano-film shows high sensitivity, fast response, good selectivity at the best operating temperature 200°C.

Gas Sensing Properties of TiO2 and SnO2 Nanopowders Obtained through Gel Combustion

2006 ◽  
Vol 45 ◽  
pp. 1828-1833
Author(s):  
Fabio A. Deorsola ◽  
P. Mossino ◽  
Ignazio Amato ◽  
Bruno DeBenedetti ◽  
A. Bonavita ◽  
...  
Keyword(s):  
Response Time ◽  
Metal Oxides ◽  
Gas Sensing ◽  
Low Cost ◽  
High Sensitivity ◽  
Fast Response ◽  
High Specific Surface Area ◽  
Research Field ◽  
Wide Range ◽  
Gel Combustion

Nanostructured semiconductor metal oxides have played a central role in the gas sensing research field, because of their high sensitivity, selectivity and low response time. Among all the processes, developed for the synthesis of nanostructured metal oxides, gel combustion seems to be the most promising route due to low-cost precursors and simplicity of the process. It combines chemical gelation and combustion, involving the formation of a gel from an acqueous solution and an exothermic redox reaction, yielding to very porous and softly agglomerated nanopowders. In this work, nanostructured tin oxide, SnO2, and titanium oxide, TiO2, have been synthesized through gel combustion. Powders showed nanometric particle size and high specific surface area. The so-obtained TiO2 and SnO2 nanopowders have been used as sensitive element of resistive λ sensor and ethanol sensor respectively, realized depositing films of nanopowders dispersed in water onto alumina substrates provided with Pt contacts and heater. TiO2-based sensors showed at high temperature good response, fast response time, linearity in a wide range of O2 concentration and long-term stability. SnO2-based sensors have shown high sensitivity to low concentrations of ethanol at moderate temperature.

scholarly journals X-Ray Fluorescence Analysis Applied to Small Samples

1977 ◽  
Vol 21 ◽  
pp. 171-185 ◽  
Author(s):  
J.M. Jaklevic ◽  
W.R. French ◽  
T.W. Clarkson ◽  
M.R. Greenwood
Keyword(s):  
Small Diameter ◽  
Fluorescence Analysis ◽  
High Sensitivity ◽  
Sample Volume ◽  
Small Sample ◽  
Small Samples ◽  
X Ray ◽  
Hair Samples ◽  
Fine Focus ◽  
Analysis System

We describe an adaptation of photon excited x-ray fluorescence analysis which is optimized for the analysis of small samples. A fine focus x-ray tube is used in conjunction with small diameter detector collimators in order to focus on a small sample volume with as high sensitivity as possible. Sample areas of less than 1 mm diameter can be analyzed with ppm detectability. In applications involving the analysis of human hair samples, a minimum detectable limit of 10 ppm Hg can be realized in a 1 mm long segment of a single hair in a counting time of 200 seconds. Simultaneous measurements of the sample mass can be obtained from the intensity of the incoherent scattering. An automated x-ray fluorescence analysis system using the technique for the scanning of elemental profiles in such hair samples will be described.

Studies on the Preparation and Gas Sensing Properties of SnO2 Nanostructures at Room Temperature

2010 ◽  
Vol 93-94 ◽  
pp. 227-230 ◽  
Author(s):  
Kiattisak Noipa ◽  
Supakorn Pukird
Keyword(s):  
Room Temperature ◽  
Gas Sensing ◽  
Sno2 Nanoparticles ◽  
High Sensitivity ◽  
Fast Response ◽  
Sno2 Nanostructures ◽  
X Rays ◽  
Sem Images ◽  
Stereo Microscope ◽  
Xrd Patterns

The SnO2 nanostructures have been synthesized by carbon-assisted growth at 800 oC for 3 hours. Using high pure tin powder as the source materials. The synthesized products were investigated by stereo microscope, X-rays diffraction (XRD) and scanning electron microscopy (SEM). XRD patterns show that the prepared products are tetragonal-structures with the lattice constant a = 0.4718 nm and c = 0.3187 nm. SEM images indicate that SnO2 nanowires are about tens of micrometers in length, 80-100 nm in width. The diameter of SnO2 nanoparticles vary from 10 nm to 100 nm. The synthesized products are high sensitivity and fast response time to ethanol gas at room temperature.

scholarly journals Development of a Highly Sensitive Nested-PCR Procedure Using a Single Closed Tube for Detection of Erwinia amylovorain Asymptomatic Plant Material

2000 ◽  
Vol 66 (5) ◽  
pp. 2071-2078 ◽  
Author(s):  
Pablo Llop ◽  
Anna Bonaterra ◽  
Javier Peñalver ◽  
María M. López
Keyword(s):  
Nested Pcr ◽  
Plant Material ◽  
High Sensitivity ◽  
Epidemiological Studies ◽  
Sample Volume ◽  
Small Sample ◽  
Asymptomatic Plant ◽  
Specificity And Sensitivity ◽  
Closed Tube ◽  
Pure Cultures

ABSTRACT A novel method, which involves a nested PCR in a single closed tube, was developed for the sensitive detection of Erwinia amylovora in plant material. The external and internal primer pairs used had different annealing temperatures and directed the amplification of a specific DNA fragment from plasmid pEA29. The procedure involved two consecutive PCRs, the first of which was performed at a higher annealing temperature that allowed amplification only by the external primer pair. Using pure cultures of E. amylovora, the sensitivity of the nested PCR in one tube was similar to that of a standard nested PCR in two tubes. The specificity and sensitivity were greater than those of standard PCR procedures that used a single primer pair. The presence of inhibitors in plant material, very common in E. amylovora hosts, is overcome with this system in combination with a simple DNA extraction protocol because it eliminates many of the inhibitory compounds. In addition, it needs a very small sample volume (1 μl of DNA extracted). With 83 samples of naturally infected material, this method achieved better results than any other PCR technique: standard PCR detected 55% of positive samples, two-tube nested PCR detected 71% of positive samples, and nested PCR in a single closed tube detected 78% of positive samples. When analyzing asymptomatic plant material, the number of positive samples detected by the developed nested PCR was also the highest, compared with the PCR protocols indicated previously (17, 20, and 25% of 251 samples analyzed, respectively). This method is proposed for the detection of endophytic and epiphytic populations of E. amylovora in epidemiological studies and for routine use in quarantine surveys, due to its high sensitivity, specificity, speed, and simplicity.

H2S DETECTION BY CuO NANOWIRES AT ROOM TEMPERATURE

2011 ◽  
Vol 10 (04n05) ◽  
pp. 733-737
Author(s):  
MANMEET KAUR ◽  
KAILASA GANAPATHI ◽  
NIYANTA DATTA ◽  
K. P. MUTHE ◽  
S. K. GUPTA
Keyword(s):  
Room Temperature ◽  
Gas Sensing ◽  
High Sensitivity ◽  
Fast Response ◽  
Oxygen Adsorption ◽  
Initial Increase ◽  
Cuo Nanowires ◽  
Cuo Nanowire ◽  
High Concentrations ◽  
Different Response

Room temperature gas sensing properties of CuO nanowires synthesized by thermal oxidation of copper foils was studied in different configurations: (i) isolated nanowires aligned between two electrodes, (ii) as grown CuO foil consisting of nanowires and (iii) CuO nanowire films. Sensors were studied for response to different gases. Different sensors showed qualitatively different response on exposure to H2S . Isolated nanowires showed high sensitivity, (~200% for 10 ppm of gas) and fast response (30 s) and recovery times (60 s). In these samples, the resistance mainly decreased on exposure to H2S (though a small initial increase was observed). In CuO foils, resistance increased for low concentrations (5–10 ppm) but decreased at high concentrations. In the case of CuO nanowire films, resistance only increased on exposure of H2S (upto 400 ppm). Since CuO is a p-type semiconductor, on exposure to H2S an increase in resistance is expected due to oxygen adsorption related process. Decrease in resistance in some of the sensors was understood in terms of reaction of CuO with H2S resulting in the formation of CuS .

scholarly journals Hydrogen Gas Sensing Using Palladium-Graphene Nanocomposite Material Based on Surface Acoustic Wave

2017 ◽  
Vol 2017 ◽  
pp. 1-6 ◽  
Author(s):  
Nguyen Hai Ha ◽  
Nguyen Hoang Nam ◽  
Dang Duc Dung ◽  
Nguyen Huy Phuong ◽  
Phan Duy Thach ◽  
...  
Keyword(s):  
Acoustic Wave ◽  
Surface Acoustic Wave ◽  
Gas Sensing ◽  
Specific Interaction ◽  
High Sensitivity ◽  
Fast Response ◽  
Hydrogen Gas ◽  
Chemical Route ◽  
Response Recovery ◽  
Sensing Material

We report the fabrication and characterization of surface acoustic wave (SAW) hydrogen sensors using palladium-graphene (Pd-Gr) nanocomposite as sensing material. The Pd-Gr nanocomposite as sensing layer was deposited onto SAW delay line sensor-based interdigitated electrodes (IDTs)/aluminum nitride (AlN)/silicon (Si) structure. The Pd-Gr nanocomposite was synthesized by a chemical route and deposited onto SAW sensors by air-brush spraying. The SAW H2 sensor using Pd-Gr nanocomposite as a sensing layer shows a frequency shift of 25 kHz in 0.5% H2 concentration at room temperature with good repeatability and stability. Moreover, the sensor showed good linearity and fast response/recovery within ten seconds with various H2 concentrations from 0.25 to 1%. The specific interaction between graphene and SAW transfer inside AlN/Si structures yields a high sensitivity and fast response/recovery of SAW H2 sensor based on Pd-Gr/AlN/Si structure.

Bio-templated fabrication of hierarchically porous WO3 microspheres from lotus pollens for NO gas sensing at low temperatures

RSC Advances ◽  
2015 ◽  
Vol 5 (37) ◽  
pp. 29428-29432 ◽  
Author(s):  
Xiao-Xue Wang ◽  
Kuan Tian ◽  
Hua-Yao Li ◽  
Ze-Xing Cai ◽  
Xin Guo
Keyword(s):  
Porous Structure ◽  
Low Temperatures ◽  
Gas Sensing ◽  
High Sensitivity ◽  
Fast Response ◽  
Hierarchically Porous ◽  
Response And Recovery

Lotus pollen was used as a template to prepare WO3 microspheres. The porous structure of the microspheres is ideal for gas sensing. The microsphere-based sensor has high sensitivity (S = 46.2) to 100 ppm NO gas with fast response and recovery speed 62 s/223 s) at 200 °C.

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