scholarly journals Detection of Emanated Light at the Modified Clad Region (Sno2) of the Optical Fiber for Methanol Gas Sensing

2020 ◽  
Vol 8 (5) ◽  
pp. 3327-3332
Keyword(s):  
Optical Fiber ◽  
Room Temperature ◽  
Gas Sensing ◽  
Output Intensity ◽  
Gas Sensitivity ◽  
Radiation Mode ◽  
Gas Concentration ◽  
Fiber Mode ◽  
Modified Surface ◽  
Different Gases

A leakage detecting sensor (radiation mode (or) double fiber mode) is proposed to monitor the light rays propagates from the surface of the modified clad region (SnO2 ) of the optical fiber. The output intensity increases and decreases for the varying gas concentration (0-500 ppm) with the presence of different gases (methanol, ethanol, acetone and ammonia) at room temperature. The received output intensity from the clad modified surface increases for ammonia and methanol, whereas, it decreases for acetone and ethanol gases for the increase in the gas concentration. However, in the transmitting mode (single fiber mode) the output light intensity decreases for all the gases with varying gas concentration. The output gas sensitivity of the proposed sensor (double fiber mode) is compared with the transmitting mode sensor and the sensor shows superior response for methanol over other gases. The dynamic characteristics of the sensor are reported.

scholarly journals Effect of GNWs/NiO-WO3/GNWs Heterostructure for NO2 Gas Sensing at Room Temperature

Sensors ◽  
2022 ◽  
Vol 22 (2) ◽  
pp. 626
Author(s):  
Seokhun Kwon ◽  
Seokwon Lee ◽  
Joouk Kim ◽  
Chulmin Park ◽  
Hosung Jung ◽  
...  
Keyword(s):  
Particulate Matter ◽  
Room Temperature ◽  
Microwave Plasma ◽  
Gas Sensing ◽  
Chemical Vapor ◽  
Gas Concentration ◽  
Negative Change ◽  
Low Concentrations ◽  
Detection Characteristics ◽  
No2 Detection

Recently, as air pollution and particulate matter worsen, the importance of a platform that can monitor the air environment is emerging. Especially, among air pollutants, nitrogen dioxide (NO2) is a toxic gas that can not only generate secondary particulate matter, but can also derive numerous toxic gases. To detect such NO2 gas at low concentration, we fabricated a GNWs/NiO-WO3/GNWs heterostructure-based gas sensor using microwave plasma-enhanced chemical vapor deposition (MPECVD) and sputter, and we confirmed the NO2 detection characteristics between 10 and 50 ppm at room temperature. The morphology and carbon lattice characteristics of the sensing layer were investigated using field emission scanning electron microscopy (FESEM) and Raman spectroscopy. In the gas detection measurement, the resistance negative change according to the NO2 gas concentration was recorded. Moreover, it reacted even at low concentrations such as 5–7 ppm, and showed excellent recovery characteristics of more than 98%. Furthermore, it also showed a change in which the reactivity decreased with respect to humidity of 33% and 66%.

scholarly journals Room-temperature synthesis and CO2-gas sensitivity of bismuth oxide nanosensors

RSC Advances ◽  
2020 ◽  
Vol 10 (29) ◽  
pp. 17217-17227 ◽  
Author(s):  
Pritamkumar V. Shinde ◽  
Nanasaheb M. Shinde ◽  
Shoyebmohamad F. Shaikh ◽  
Damin Lee ◽  
Je Moon Yun ◽  
...  
Keyword(s):  
Carbon Dioxide ◽  
Bismuth Oxide ◽  
Room Temperature ◽  
Gas Sensing ◽  
Deposition Method ◽  
Gas Sensitivity ◽  
Temperature Synthesis ◽  
Co2 Gas ◽  
Surface Areas ◽  
Sensing Applications

Room-temperature (27 °C) synthesis and carbon dioxide (CO2)-gas-sensing applications of bismuth oxide (Bi2O3) nanosensors obtained via a direct and superfast chemical-bath-deposition method (CBD) with different surface areas and structures.

Gas Sensing Properties of Porous ZnO Nano-Platelet Films

2007 ◽  
Vol 1035 ◽  
Author(s):  
Amandeep Saluja ◽  
Jie Pan ◽  
Lei Kerr ◽  
Eunjung Cho ◽  
Seth Hubbard
Keyword(s):  
Gas Flow ◽  
Room Temperature ◽  
Gas Sensing ◽  
Electrode Spacing ◽  
Porous Films ◽  
Gas Sensitivity ◽  
Gas Sensing Properties ◽  
Recovery Times ◽  
Response And Recovery ◽  
Carrier Gas Flow

AbstractIn this work, various ZnO nanostructures were synthesized and a detailed study on the effect of different process parameters such as temperature, carrier gas flow, inter-electrode spacing, gas concentration and material properties on gas sensitivity was conducted. Initial ZnO nanoparticles were prepared by a simple solution chemical process and characterized by Secondary Electron Microscopy (SEM) and Brunauer, Emmet and Teller (BET) Sorptometer to demonstrate the morphology and surface area respectively. Sensitivity of nano-platelets and porous films was measured for different concentrations of the analytes (H2, CO). High response was observed at room temperature for H2 gas with sensitivities in excess 80% for 60ppm and about 55% for 80ppm of H2 gas at room temperature were observed for the nano-platelets and the porous films respectively with short response and recovery times of about 200 seconds. The sensitivity of the nano-platelets to CO gas was also measured and found to be about near 90% for 80 ppm CO at operating temperatures of 200 °C.

Research on the Optical Fiber Gas Sensing System Based on the Gas Concentration Measurement

2012 ◽  
Vol 529 ◽  
pp. 487-491 ◽  
Author(s):  
Bao Hu Gu ◽  
Ze Fa Fang
Keyword(s):  
Optical Fiber ◽  
Gas Sensing ◽  
High Sensitivity ◽  
Gas Absorption ◽  
Concentration Measurement ◽  
Mine Safety ◽  
Social Significance ◽  
Gas Concentration ◽  
Economic Significance ◽  
Mine Gas

At present , the catalytic combustion type gas sensors is still used in our country which is the extensive use of underground coal mine gas detection instrument , this kind of sensor slow response, calibration cycle is short, and the apparatus for the selectivity of methane is poor. Thus it can be seen that develop a safe and reliable, selective, high sensitivity of gas concentration measurement system that for mine safety operation, the personal safety and environment protection has a very important social significance and economic significance. Optical fiber sensing monitoring system according to the gas absorption spectrum principle with double light path structure on the mine gas online monitoring the concentration of the gas, has avoid the explosion, dust and so on many special advantages.

scholarly journals N-doped reduced graphene oxide for room-temperature NO gas sensors

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Yu-Sung Chang ◽  
Feng-Kuan Chen ◽  
Du-Cheng Tsai ◽  
Bing-Hau Kuo ◽  
Fuh-Sheng Shieu
Keyword(s):  
Graphene Oxide ◽  
Reduced Graphene Oxide ◽  
Room Temperature ◽  
Gas Sensing ◽  
Ambient Conditions ◽  
Gas Sensitivity ◽  
Nitrogen Doped ◽  
Low Concentrations ◽  
Reduced Graphene ◽  
P Type

AbstractIn this study, we use nitrogen-doped to improving the gas-sensing properties of reduced graphene oxide. Graphene oxide was prepared according to a modified Hummers’ method and then nitrogen-doped reduced graphene oxide (N-rGO) was synthesized by a hydrothermal method using graphene oxide and NH4OH as precursors. The rGO is flat and smooth with a sheet-like morphology while the N-rGO exhibits folded morphology. This type of folding of the surface morphology can increase the gas sensitivity. The N-rGO and the rGO sensors showed n-type and p-type semiconducting behaviors in ambient conditions, respectively, and were responsive to low concentrations of NO gases (< 1000 ppb) at room temperature. The gas-sensing results showed that the N-rGO sensors could detect NO gas at concentrations as low as 400 ppb. The sensitivity of the N-rGO sensor to 1000 ppb NO (1.7) is much better than that of the rGO sensor (0.012). Compared with pure rGO, N-rGO exhibited a higher sensitivity and excellent reproducibility.

scholarly journals Enhancement of SnO2 for gas sensing applications

2021 ◽  
Vol 32 (3) ◽  
pp. 63
Author(s):  
O. S. Mahdi ◽  
Nadheer Jassim Mohammed
Keyword(s):  
Thin Films ◽  
Room Temperature ◽  
Gas Sensing ◽  
Rf Magnetron Sputtering ◽  
Ethanol Vapor ◽  
Gas Sensitivity ◽  
Sensing Applications ◽  
Sno2 Thin Films ◽  
The Rich ◽  
Reactive Rf Magnetron Sputtering

Thin films of SnO2 were deposited by reactive RF magnetron sputtering. It was shown that the films possess gas sensitivity to ethanol vapor at room temperature. XRD, SEM, and EDX measurements of thin films were investigated. Annealing of SnO2 thin films at 800 °С is polycrystalline and grain size of SnO2 in the range about 12 nm. The growth of SnO2 with annealing to 800 °C leads to the percolation nanorods structure. EDX clearly explains the rich of Sn reached 70% annealing. The conductivity of SnO2 nanorods has been increasing at room temperature for ethanol vapors. 

scholarly journals Gas Sensing of (SnO2)1-x(ZnO)x Composite Associating with Electrical Properties

2019 ◽  
Vol 17 (43) ◽  
pp. 49-57
Author(s):  
Dunia Yas
Keyword(s):  
Tin Oxide ◽  
Gas Sensing ◽  
Charge Carrier Mobility ◽  
X Ray Diffraction ◽  
Gas Sensitivity ◽  
Gas Concentration ◽  
Sensing Applications ◽  
Maximum Electron Density ◽  
Direct Current Conductivity ◽  
Hall Effect Measurements

Abstract Semiconductor-based gas sensors were prepared, that use n-type tin oxide (SnO2) and  tin oxide: zinc oxide composite (SnO2)1-x(ZnO)x at different x ratios using pulse laser deposition at room temperature. The prepared thin films were examined to reach the optimum conditions for gas sensing applications, namely X-ray diffraction, Hall effect measurements, and direct current conductivity. It was found that the optimum crystallinity and maximum electron density, corresponding to the minimum charge carrier mobility, appeared at 10% ZnO ratio. This ratio appeared has the optimum NO2 gas sensitivity for 5% gas concentration at 300 °C working temperature.

Nanocomposite of Ag-Polyacrylonitryle as a Selective Chlorine Sensor

2013 ◽  
Vol 804 ◽  
pp. 135-140 ◽  
Author(s):  
Tatiana V. Semenistaya ◽  
Victor V. Petrov ◽  
Ping Lu
Keyword(s):  
Process Parameters ◽  
Original Film ◽  
Room Temperature ◽  
Gas Sensing ◽  
Film Material ◽  
Gas Sensitivity ◽  
Electronic Engineering ◽  
Film Forming ◽  
Ir Pyrolysis ◽  
Gas Sensing Properties

Gas-sensing elements based on Ag-containing polyacrylonitrile (PAN) films using different temperature and time modes of a two stage IR-pyrolysis have been fabricated. It has been investigated that the gas sensitivity of the samples depends on the composition of the original film-forming solution and on the process parameters of forming the film material. It has been studied that the samples demonstrate gas-sensing properties to Cl2 at room temperature. The outcome of this study is that Ag-containing PAN films can be considered as one of the most promising material to be used in electronic engineering.

scholarly journals Low-Operating-Temperature NO2 Sensor Based on a CeO2/ZnO Heterojunction

Sensors ◽  
2021 ◽  
Vol 21 (24) ◽  
pp. 8269
Author(s):  
Kai Sun ◽  
Guanghui Zhan ◽  
Hande Chen ◽  
Shiwei Lin
Keyword(s):  
Hydrothermal Treatment ◽  
Room Temperature ◽  
Gas Sensing ◽  
Operating Temperature ◽  
Nanorod Array ◽  
Gas Sensitivity ◽  
Anodic Electrodeposition ◽  
No2 Sensor ◽  
Higher Sensitivity ◽  
Sensing Performance

CeO2/ZnO-heterojunction-nanorod-array-based chemiresistive sensors were studied for their low-operating-temperature and gas-detecting characteristics. Arrays of CeO2/ZnO heterojunction nanorods were synthesized using anodic electrodeposition coating followed by hydrothermal treatment. The sensor based on this CeO2/ZnO heterojunction demonstrated a much higher sensitivity to NO2 at a low operating temperature (120 °C) than the pure-ZnO-based sensor. Moreover, even at room temperature (RT, 25 °C) the CeO2/ZnO-heterojunction-based sensor responds linearly and rapidly to NO2. This sensor’s reaction to interfering gases was substantially less than that of NO2, suggesting exceptional selectivity. Experimental results revealed that the enhanced gas-sensing performance at the low operating temperature of the CeO2/ZnO heterojunction due to the built-in field formed after the construction of heterojunctions provides additional carriers for ZnO. Thanks to more carriers in the ZnO conduction band, more oxygen and target gases can be adsorbed. This explains the enhanced gas sensitivity of the CeO2/ZnO heterojunction at low operating temperatures.

scholarly journals AZO-Based ZnO Nanosheet MEMS Sensor with Different Al Concentrations for Enhanced H2S Gas Sensing

Nanomaterials ◽  
2021 ◽  
Vol 11 (12) ◽  
pp. 3377
Author(s):  
Yempati Nagarjuna ◽  
Jun-Cong Lin ◽  
Sheng-Chang Wang ◽  
Wen-Tse Hsiao ◽  
Yu-Jen Hsiao
Keyword(s):  
Zinc Oxide ◽  
Gas Sensing ◽  
Growth Time ◽  
Optimal Conditions ◽  
Gas Concentration ◽  
Zno Nanostructure ◽  
Mems Sensor ◽  
Different Temperatures ◽  
Micro Electromechanical System ◽  
Different Gases

The properties of H2S gas sensing were investigated using a ZnO nanostructure prepared with AZO (zinc oxide with aluminium) and Al surfaces which were developed on a MEMS (Micro Electromechanical System) device. Hydrothermal synthesis was implemented for the deposition of the ZnO nanostructure. To find the optimal conditions for H2S gas sensing, different ZnO growth times and different temperatures were considered and tested, and the results were analysed. At 250 °C and 90 min growth time, a ZnO sensor prepared with AZO and 40 nm Al recorded an 8.5% H2S gas-sensing response at a 200 ppb gas concentration and a 14% sensing response at a gas concentration of 1000 ppb. The dominant sensing response provided the optimal conditions for the ZnO sensor, which were 250 °C temperature and 90 min growth time. Gas sensor selectivity was tested with five different gases (CO, SO2, NO2, NH3 and H2S) and the sensor showed great selectivity towards H2S gas.

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