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Gas sensors

HyeongU Kim, Juhyun Son, Atul Kulkarni, Chisung Ahn, Ki Seok Kim, Dongjoo Shin, Geun Yeom, Taesung Kim
Molybdenum oxide (MoO<sub>3</sub>) has gained immense attention because of its high electron mobility, wide band gap, and excellent optical and catalytic properties. However, the synthesis of uniform and large-area MoO<sub>3</sub> is challenging. Here, we report the synthesis of wafer-scale α-MoO3 by plasma oxidation of Mo-deposited on Si/SiO<sub>2</sub>. Mo was oxidized by O<sub>2</sub> plasma in a plasma enhanced chemical vapor deposition (PECVD) system at 150 °C...
March 20, 2017: Nanotechnology
Pablo Giménez-Gómez, Manuel Gutiérrez-Capitán, Anna Puig-Pujol, Fina Capdevila, Sergio Muñoz, Andreu Tobeña, Antoni Miró, Cecilia Jiménez-Jorquera
The use of sulfur dioxide as preservative in winemaking industry has a direct impact on wine quality. The standard methods to analyze this parameter require several processes and are time consuming. In this paper a simple and rapid analytical method for free and total sulfur dioxide detection is proposed. This method is based on the separation of the analyte from the sample with a permeable gas diffusion membrane and its indirect detection with a pH sensor. The system has been validated and optimized for free sulfur dioxide detection in the range of 1-60mgL(-1) and for total sulfur dioxide in the range of 30-300mgL(-1) with a limit of detection of 0...
August 1, 2017: Food Chemistry
Zhuo Chen, Jinrong Wang, Ahmad Umar, Yao Wang, Hao Li, Guofu Zhou
It is well established that the structures dominate the properties. Inspired by the highly contorted and crumpled maxilloturbinate inside dog nose, herein an artificial nanostructure, i.e. 3D crumpled graphene-based nanosheets, is reported with the simple fabrication, detailed characterizations and efficient gas sensing applications. A facile supramolecular non-covalent assembly is introduced to modify graphene with functional molecules, followed with a lyophilization process to massively transform 2D plane graphene-based nanosheets to 3D crumpled structure...
March 16, 2017: ACS Applied Materials & Interfaces
F Rigoni, C Pintossi, G Drera, S Pagliara, G Lanti, P Castrucci, M De Crescenzi, L Sangaletti
A combination of the functionalities of carbon nanotube (CNT)-Si hybrid heterojunctions is presented as a novel method to steer the efficiency of the photovoltaic (PV) cell based on these junctions, and to increase the selectivity and sensitivity of the chemiresistor gas sensor operated with the p-doped CNT layer. The electrical characteristics of the junctions have been tracked by exposing the devices to oxidizing (NO2) and reducing (NH3) molecules. It is shown that when used as PV cells, the cell efficiency can be reversibly steered by gas adsorption, providing a tool to selectively dope the p-type layer through molecular adsorption...
March 15, 2017: Scientific Reports
Fu-An Li, Han Jin, Jinxia Wang, Jie Zou, Jiawen Jian
A new strategy to discriminate four types of hazardous gases is proposed in this research. Through modulating the operating temperature and the processing response signal with a pattern recognition algorithm, a gas sensor consisting of a single sensing electrode, i.e., ZnO/In₂O₃ composite, is designed to differentiate NO₂, NH₃, C₃H₆, CO within the level of 50-400 ppm. Results indicate that with adding 15 wt.% ZnO to In₂O₃, the sensor fabricated at 900 °C shows optimal sensing characteristics in detecting all the studied gases...
March 12, 2017: Sensors
Milena Šetka, Jana Drbohlavová, Jaromír Hubálek
The aim of this review is to summarize the recent progress in the fabrication of efficient nanostructured polymer-based sensors with special focus on polypyrrole. The correlation between physico-chemical parameters, mainly morphology of various polypyrrole nanostructures, and their sensitivity towards selected gas and volatile organic compounds (VOC) is provided. The different approaches of polypyrrole modification with other functional materials are also discussed. With respect to possible sensors application in medicine, namely in the diagnosis of diseases via the detection of volatile biomarkers from human breath, the sensor interaction with humidity is described as well...
March 10, 2017: Sensors
Linda Carton, Peter Ache
This paper presents one emerging social-technical innovation: The evolution of citizen-sensor-networks where citizens organize themselves from the 'bottom up', for the sake of confronting governance officials with measured information about environmental qualities. We have observed how citizen-sensor-networks have been initiated in the Netherlands in cases where official government monitoring and business organizations leave gaps. The formed citizen-sensor-networks collect information about issues that affect the local community in their quality-of-living...
March 9, 2017: Journal of Environmental Management
A A Bagade, V V Ganbavle, S V Mohite, T D Dongale, B B Sinha, K Y Rajpure
Polycrystalline CoFe2O4 thin films are deposited onto the quartz substrates by spray pyrolysis technique. Rietveld refinement analysis confirmed the films are polycrystalline in nature with spinel cubic crystal structure. Rietveld refinement analysis was employed to estimate the cation distribution in spinel lattice sites. Surface micrographs shows the granular morphology with average grain size decreases with increase in solution concentration. The presence of two characteristic absorption bands around 579 and 391cm(-1) in the FTIR study confirms the formation of single phase CoFe2O4...
March 1, 2017: Journal of Colloid and Interface Science
Xiaoxing Zhang, Hao Cui, Yingang Gui, Ju Tang
Carbon nanotubes (CNTs) have aroused extensive attentions as a new category of gas sensor materials owing to their outstanding performance for detecting specific gas among a variety of ones through diverse gas responses. This review summarizes the adsorption mechanism of CNTs and their properties related to the detection of sulfur hexafluoride (SF6) decomposed gases that generated in gas insulation switchgear (GIS) of power system. Their performances as sensors of both experimental analysis and theoretical calculation for various kinds of decomposed gases are summarized, and the further research trend on CNTs in the detection of SF6 decomposition components is also put forward...
December 2017: Nanoscale Research Letters
Lu Yan, Zhiguo Gui, Guanjun Wang, Yongquan An, Jinyu Gu, Meiqin Zhang, Xinglin Liu, Zhibin Wang, Gao Wang, Pinggang Jia
A high-sensitivity, low-cost, ultrathin, hollow fiber micro bubble structure was proposed; such a bubble can be used to develop a high-sensitivity strain sensor based on a Fabry-Perot interferometer (FPI). The micro bubble is fabricated at the fiber tip by splicing a glass tube to a single mode fiber (SMF) and then the glass tube is filled with gas in order to expand and form a micro bubble. The sensitivity of the strain sensor with a cavity length of about 155 μm and a bubble wall thickness of about 6 μm was measured to be up to 8...
March 9, 2017: Sensors
Nanshu Liu, Si Zhou
Monolayer blue phosphorus has recently been synthesized by molecular beam epitaxial growth on Au(111) substrate. It is intriguing to compare this new 2D phase of phosphorus with phosphorene in both the fundamental properties and application prospects. Here, first-principles calculations are carried out to explore the adsorption behaviors of environmental gas molecules on monolayer blue phosphorous, including O<sub>2</sub>, NO, SO<sub>2</sub>, NH<sub>3</sub>, H<sub>2</sub>O, NO<sub>2</sub>, CO<sub>2</sub>, H<sub>2</sub>S, CO and N<sub>2</sub>, and address their effects on the electronic properties of the material...
March 10, 2017: Nanotechnology
Ali Fares, Adam Bensley, Haimanote Bayabil, Ripendra Awal, Samira Fares, Hector Valenzuela, Farhat Abbas
Soil moisture and organic matter level affects soil respiration and microbial activities, which in turn impact greenhouse gas (GHG) emissions. This study was conducted to evaluate the effect of irrigation levels (75% [deficit], 100% [full], and 125% [excess] of reference crop evapotranspiration requirements), and organic amendments (OA) type (chicken manure [CM] and bone meal [BM]) and OA application rates (0,168, 336 and 672 kg total N ha(-1)) on (i) soil physical properties (bulk density, organic matter content and soil moisture content) and (ii) soil carbon dioxide (CO2) emissions from a highly weathered tropical Hawai'ian soil...
March 3, 2017: Journal of Environmental Science and Health. Part. B, Pesticides, Food Contaminants, and Agricultural Wastes
Edgar R López-Mena, Carlos R Michel, Alma H Martínez-Preciado, Alex Elías-Zuñiga
In this work, nanostructured CeO2 microspheres with high surface area and mesoporosity were prepared by the coprecipitation method, in absence of a template. The reaction between cerium nitrate and concentrated formic acid produced cerium formate, at room temperature. Further, calcination at 300 °C yielded single-phase CeO2 microspheres, with a diameter in the range 0.5-2.6 μm, the surface of these microspheres is completely nanostructured (diameter about 30-90 nm). CeO2 microspheres were used to fabricate a sensor device, and it was tested for intermediate CO gas concentrations (200-800 ppm)...
December 2017: Nanoscale Research Letters
Georgios Niarchos, Georges Dubourg, Georgios Afroudakis, Markos Georgopoulos, Vasiliki Tsouti, Eleni Makarona, Vesna Crnojevic-Bengin, Christos Tsamis
In this paper, we investigated the effect of humidity on paper substrates and propose a simple and low-cost method for their passivation using ZnO nanoparticles. To this end, we built paper-based microdevices based on an interdigitated electrode (IDE) configuration by means of a mask-less laser patterning method on simple commercial printing papers. Initial resistive measurements indicate that a paper substrate with a porous surface can be used as a cost-effective, sensitive and disposable humidity sensor in the 20% to 70% relative humidity (RH) range...
March 4, 2017: Sensors
Jacek Wojtas, Aleksander Gluszek, Arkadiusz Hudzikowski, Frank K Tittel
The application of compact inexpensive trace gas sensor technology to a mid-infrared nitric oxide (NO) detectoion using intracavity quartz-enhanced photoacoustic spectroscopy (I-QEPAS) is reported. A minimum detection limit of 4.8 ppbv within a 30 ms integration time was demonstrated by using a room-temperature, continuous-wave, distributed-feedback quantum cascade laser (QCL) emitting at 5.263 µm (1900.08 cm(-1)) and a new compact design of a high-finesse bow-tie optical cavity with an integrated resonant quartz tuning fork (QTF)...
March 4, 2017: Sensors
Zhixiang Wang, Gordon R Jones, Joseph W Spencer, Xiaohua Wang, Mingzhe Rong
Contact erosion is one of the most crucial factors affecting the electrical service lifetime of high-voltage circuit breakers (HVCBs). On-line monitoring the contacts' erosion degree is increasingly in demand for the sake of condition based maintenance to guarantee the functional operation of HVCBs. A spectroscopic monitoring system has been designed based upon a commercial 245 kV/40 kA S F 6 live tank circuit breaker with copper-tungsten (28 wt % and 72 wt %) arcing contacts at atmospheric S F 6 pressure. Three optical-fibre based sensors are used to capture the time-resolved spectra of arcs...
March 6, 2017: Sensors
Gareth Williams, Saiyi Li, Pubudu N Pathirana
Building on previous experiments in the domain of energy expenditure estimation using wearable sensors, the measurements of energy ratios of a runner on a treadmill were analyzed to observe any commonalities between an inertia measurement unit and an electromyograph sensor. The subjects were equipped with a VO2 gas measurement device, an Inertial Measurement Unit (IMU) measuring gyroscopic activity and an electromyography (EMG) sensor network whilst running at 5 different speeds on a calibrated treadmill. The observed results established a co-linear relationship with the gyroscope based measurements, EMG based measurements with the VO2 measurements...
August 2016: Conference Proceedings: Annual International Conference of the IEEE Engineering in Medicine and Biology Society
Yue Deng, Cheng Chen, Francis Tsow, Xiaojun Xian, Erica Forzani
Volatile organic compounds (VOC) are organic chemicals that have high vapor pressure at regular conditions. Some VOC could be dangerous to human health, therefore it is important to determine real-time indoor and outdoor personal exposures to VOC. To achieve this goal, our group has developed a wearable gas monitor with a complete sensor fabrication and calibration protocol for free-living conditions. Correction factors for calibrating the sensors, including sensitivity, aging effect, and temperature effect are implemented into a Quick Response Code (QR code), so that the pre-calibrated quartz tuning fork (QTF) sensor can be used with the wearable monitor under free-living conditions...
August 2016: Conference Proceedings: Annual International Conference of the IEEE Engineering in Medicine and Biology Society
Anthony R Flores, Randall J Olsen, Concepcion Cantu, Kyler B Pallister, Fermin E Guerra, Jovanka M Voyich, James M Musser
Studies of the human pathogen group A Streptococcus (GAS) define the carrier phenotype as increased ability to adhere to and persist on epithelial surfaces and decreased ability to cause disease. We tested the hypothesis that a single amino acid change (Arg135Gly) in a highly conserved sensor kinase (LiaS) of a poorly defined GAS regulatory system contributes to a carrier phenotype through increased pilus production. When introduced into an emm serotype-matched invasive strain, the carrier allele (liaS(R135G)) recapitulated a carrier phenotype defined by increased ability to adhere to mucosal surfaces and decreased ability to cause disease...
March 6, 2017: Infection and Immunity
Muhammad A Zaheer, Jeremias C Zill, Jörg Matysik, Roger Gläser, Muslim Dvoyashkin
¹²⁹Xe NMR spectroscopy is applied under in situ and in operando conditions to study the mixing process in a multicomponent liquid mixture with partially miscible components. The process of mixing of an oil-methanol mixture was triggered by an industrially relevant catalytic transesterification reaction to form fatty acid methyl esters and glycerol. Up to date, kinetic limitations in liquid phase reactions originating from the poor miscibility of reacting species were addressed solely under ex situ conditions, typically by chromatography...
March 3, 2017: Chemphyschem: a European Journal of Chemical Physics and Physical Chemistry
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