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Gas sensors

Adam L Friedman, Aubrey T Hanbicki, F Keith Perkins, Glenn G Jernigan, James C Culbertson, Paul M Campbell
Electron-donors can impart charge to the surface of transition metal dichalcogenide (TMD) films while interacting with the film via a weak physisorption bond, making them ideal for vapor and gas sensors. We expose monolayer MoS2 and MoSe2 films to strong electron-donor chemical vapor analytes. After analyzing the resultant behavior and taking into consideration doping effects, we conclude that exposure to strong electron-donors could be a method of inducing the semiconductor-metal 2H-1T TMD phase transition...
June 19, 2017: Scientific Reports
Sayed Ali Akbar Razavi, Mohammad Yaser Masoomi, Ali Morsali
The ligands (3,6-di(pyridin-4-yl)-1,4-dihydro-1,2,4,5-tetrazine), H2DPT, as a pillar spacer and (4,4'-oxybis(benzoic acid)), H2OBA, as a dicarboxylate linker were used to develop a dihydro-tetrazine functionalized pillared-MOF, [Zn(OBA)(H2DPT)0.5].DMF (TMU-34) as functionally convertible stimuli responsive MOF-based Sensor. Sonochemically synthesized powder of TMU-34 was employed in sensing of volatile organic compounds (VOCs). The results show that TMU-34 can act as a solid state naked-eye visual chemosensor for detection of chloroform in liquid and gas phases...
June 17, 2017: Chemistry: a European Journal
Yousra Timounay, Olivier Pitois, Florence Rouyer
Enwrapping liquid droplets with hydrophobic particles allows the manufacture of so-called "liquid marbles" [Aussillous and Quéré Nature (London) 411, 924 (2001); NATUAS0028-083610.1038/35082026Mahadevan Nature (London)411, 895 (2001)NATUAS0028-083610.1038/35082164]. The recent intensive research devoted to liquid marbles is justified by their very unusual physical and chemical properties and by their potential for various applications, from microreactors to water storage, including water pollution sensors [Bormashenko Curr...
June 2, 2017: Physical Review Letters
Christoph Oliver Blattmann, Andreas T T Güntner, Sotiris E Pratsinis
Flame-deposited semiconducting nanomaterials on microelectronic circuitry exhibit exceptional performance as chemoresistive gas sensors. Current manufacturing technology, however, does not monitor in situ the formation of such nanostructured films even though this can facilitate the controlled and economic synthesis of these sensors. Here, the resistance of such growing films is measured in situ during fabrication to monitor the creation of a semiconducting nanoparticle network for gas sensors. Upon formation of that network, the film resistance drops drastically to an asymptotic value that depends largely on film structure or morphology rather than on its thickness and nanoparticle size...
June 16, 2017: ACS Applied Materials & Interfaces
Aurelian Marcu, Cristian Viespe
A delay-line-type surface acoustic wave (SAW) sensor based on a zinc oxide (ZnO) sensitive layer was developed. Two types of sensitive layers were obtained: ZnO nanowires and ZnO thin films, both deposited using laser methods (VLS-PLD and PLD, respectively) onto quartz substrates. The responses of sensors with two different nanowire lengths (300 and 600 nm) were compared with those of sensors with thin films of different thicknesses (ca. 100 and 200 nm) to different concentrations of hydrogen and deuterium...
June 16, 2017: Sensors
Lionel Presmanes, Yohann Thimont, Imane El Younsi, Audrey Chapelle, Frédéric Blanc, Chabane Talhi, Corine Bonningue, Antoine Barnabé, Philippe Menini, Philippe Tailhades
P-type semiconducting copper oxide (CuO) thin films deposited by radio-frequency (RF) sputtering were integrated onto microsensors using classical photolithography technologies. The integration of the 50-nm-thick layer could be successfully carried out using the lift-off process. The microsensors were tested with variable thermal sequences under carbon monoxide (CO), ammonia (NH₃), acetaldehyde (C₂H₄O), and nitrogen dioxide (NO₂) which are among the main pollutant gases measured by metal-oxide (MOS) gas sensors for air quality control systems in automotive cabins...
June 16, 2017: Sensors
Xian Li, Jiang Wang, Dan Xie, Jianlong Xu, Yi Xia, Weiwei Li, Lan Xiang, Zhemin Li, Shiwei Xu, Sridhar Komarneni
Gas sensors based on reduced graphene oxide (rGO) films and rGO/MoS2 hybrid films were fabricated on polyethylene naphthalate (PEN) substrates by a simple self-assembly method, which yielded flexible devices for detection of formaldehyde (HCHO) at room temperature. The sensing test results indicated that the rGO and rGO/MoS2 sensors were highly sensitive and fully recoverable to ppm-level of HCHO. The bending and fatigue test results revealed that the sensors were also mechanically robust, durable and effective for long-term...
June 15, 2017: Nanotechnology
Wei Huang, Xinming Zhuang, Ferdinand S Melkonyan, Binghao Wang, Li Zeng, Gang Wang, Shijiao Han, Michael J Bedzyk, Junsheng Yu, Tobin J Marks, Antonio Facchetti
A new type of nitrogen dioxide (NO2 ) gas sensor based on copper phthalocyanine (CuPc) thin film transistors (TFTs) with a simple, low-cost UV-ozone (UVO)-treated polymeric gate dielectric is reported here. The NO2 sensitivity of these TFTs with the dielectric surface UVO treatment is ≈400× greater for [NO2 ] = 30 ppm than for those without UVO treatment. Importantly, the sensitivity is ≈50× greater for [NO2 ] = 1 ppm with the UVO-treated TFTs, and a limit of detection of ≈400 ppb is achieved with this sensing platform...
June 14, 2017: Advanced Materials
Min-Gu Kim, Hommood Alrowais, Choongsoon Kim, Pyungwoo Yeon, Maysam Ghovanloo, Oliver Brand
Lightweight, flexible, stretchable, and wireless sensing platforms have gained significant attention for personal healthcare and environmental monitoring applications. This paper introduces an all-soft (flexible and stretchable), battery-free, and wireless chemical microsystem using gallium-based liquid metal (eutectic gallium-indium alloy, EGaIn) and poly(dimethylsiloxane) (PDMS), fabricated using an advanced liquid metal thin-line patterning technique based on soft lithography. Considering its flexible, stretchable, and lightweight characteristics, the proposed sensing platform is well suited for wearable sensing applications either on the skin or on clothing...
June 14, 2017: Lab on a Chip
Juan Carlos Iglesias-Rojas, Felipe Gomez-Castañeda, Jose Antonio Moreno-Cadenas
In this paper, a Least Mean Square (LMS) programming scheme is used to set the offset voltage of two operational amplifiers that were built using floating-gate transistors, enabling a 0.95 VRMS trimmer-less flame detection sensor. The programming scheme is capable of setting the offset voltage over a wide range of values by means of electron injection. The flame detection sensor consists of two programmable offset operational amplifiers; the first amplifier serves as a 26 μV offset voltage follower, whereas the second amplifier acts as a programmable trimmer-less voltage comparator...
June 14, 2017: Sensors
Torben Daeneke, Nripen Dahr, Paul Atkin, Rhiannon M Clark, Christopher J Harrison, Robert Brkljača, Naresh Pillai, Bao Yue Zhang, Ali Zavabeti, Samuel J Ippolito, Kyle J Berean, Jian Zhen Ou, Michael S Strano, Kourosh Kalantar-Zadeh
Sulfur-rich molybdenum sulfides are an emerging class of inorganic coordination polymers that are predominantly utilized for their superior catalytic properties. Here we investigate surface water dependent properties of sulfur-rich MoSx (x = 3(2)/3) and its interaction with water vapor. We report that MoSx is a highly hygroscopic semiconductor, which can reversibly bind up to 0.9 H2O molecule per Mo. The presence of surface water is found to have a profound influence on the semiconductor's properties, modulating the material's photoluminescence by over 1 order of magnitude, in transition from dry to moist ambient...
June 14, 2017: ACS Nano
Weiwu Chen, Zhaojun Qin, Yingkai Liu, Yan Zhang, Yanbo Li, Si Shen, Zhiming M Wang, Hai-Zhi Song
SnO2 nanobelts (NBs) have unique structural and functional properties which attract great attention in gas detecting. In this work, Eu doping is adopted to improve the gas sensitivity of pure SnO2, especially to enhance the response to one single gas. The Eu-doped SnO2 NBs, pure-SnO2 NBs, and their single NB devices are fabricated by simple techniques. The sensing properties of the two sensors have been experimentally investigated. It is found that the two sensors possess long-term stability with rapid response performance, and Eu doping improves the electronic performance and the gas-sensing response, particularly to acetone...
December 2017: Nanoscale Research Letters
Katie R Smith, Peter M Edwards, Mathew J Evans, James D Lee, Marvin D Shaw, Freya Squires, Shona Wilde, Alastair C Lewis
Low cost air pollution sensors have substantial potential for atmospheric research and for the applied control of pollution in the urban environment, including more localized warnings to the public. The current generation of single-chemical gas sensors experience degrees of interference from other co-pollutants and have sensitivity to environmental factors such as temperature, wind speed and supply voltage. There are uncertainties introduced also because of sensor-to-sensor response variability, although this is less well reported...
June 13, 2017: Faraday Discussions
Sylvie Delepine-Lesoille, Sylvain Girard, Marcel Landolt, Johan Bertrand, Isabelle Planes, Aziz Boukenter, Emmanuel Marin, Georges Humbert, Stéphanie Leparmentier, Jean-Louis Auguste, Youcef Ouerdane
This paper presents the state of the art distributed sensing systems, based on optical fibres, developed and qualified for the French Cigéo project, the underground repository for high level and intermediate level long-lived radioactive wastes. Four main parameters, namely strain, temperature, radiation and hydrogen concentration are currently investigated by optical fibre sensors, as well as the tolerances of selected technologies to the unique constraints of the Cigéo's severe environment. Using fluorine-doped silica optical fibre surrounded by a carbon layer and polyimide coating, it is possible to exploit its Raman, Brillouin and Rayleigh scattering signatures to achieve the distributed sensing of the temperature and the strain inside the repository cells of radioactive wastes...
June 13, 2017: Sensors
Xiaodong Wu, Yangyang Han, Xinxing Zhang, Canhui Lu
Conductive polymer composites (CPCs) have been intensively exploited as remarkable liquid sensing materials based on variations in their conductivity under liquid stimuli. However, most advances in liquid sensing CPCs are limited to bulk materials. Due to the slow permeation of liquids into the compact CPCs, sluggish responses are inevitable for most existing CPC-based liquid sensing materials. Here, we developed a new class of liquid sensing materials via a hierarchical structure design. Specifically, a thin CPC layer with a segregated conductive network was coated on porous polyurethane (PU) skeletons by layer-by-layer assembly, forming an elaborately designed hierarchical structure in the prepared CPC@PU composites...
June 21, 2017: Physical Chemistry Chemical Physics: PCCP
Daniel W Nebert
The basic-helix-loop-helix Per-Arnt-Sim (bHLH/PAS) family comprises many transcription factors, found throughout all three kingdoms of life; bHLH/PAS members "sense" innumerable intracellular and extracellular "signals" - including endogenous compounds, foreign chemicals, gas molecules, redox potential, photons (light), gravity, heat, and osmotic pressure. These signals then initiate downstream signaling pathways involved in responding to that signal. The term "PAS", abbreviation for "Per-Arnt-Sim" was first coined in 1991...
June 9, 2017: Progress in Lipid Research
Sajjad Hossain, Lisa-Marie Nisbett, Elizabeth M Boon
Bacterial biofilms form when bacteria adhere to a surface and produce an exopolysaccharide matrix ( Costerton Science 1999 , 284 , 1318 ; Davies Science 1998 , 280 , 295 ; Flemming Nat. Rev. Microbiol. 2010 , 8 , 623 ). Because biofilms are resistant to antibiotics, they are problematic in many aspects of human health and welfare, causing, for instance, persistent fouling of medical implants such as catheters and artificial joints ( Brunetto Chimia 2008 , 62 , 249 ). They are responsible for chronic infections in the lungs of cystic fibrosis patients and in open wounds, such as those associated with burns and diabetes...
June 12, 2017: Accounts of Chemical Research
Francesco Bertocci, Ada Fort, Valerio Vignoli, Marco Mugnaini, Rossella Berni
Eight different types of nanostructured perovskites based on YCoO 3 with different chemical compositions are prepared as gas sensor materials, and they are studied with two target gases NO 2 and CO. Moreover, a statistical approach is adopted to optimize their performance. The innovative contribution is carried out through a split-plot design planning and modeling, also involving random effects, for studying Metal Oxide Semiconductors (MOX) sensors in a robust design context. The statistical results prove the validity of the proposed approach; in fact, for each material type, the variation of the electrical resistance achieves a satisfactory optimized value conditional to the working temperature and by controlling for the gas concentration variability...
June 10, 2017: Sensors
Hao Wan, Heyu Yin, Andrew J Mason
Intense study on gas sensors has been conducted to implement fast gas sensing with high sensitivity, reliability and long lifetime. This paper presents a rapid amperometric method for gas sensing based on a room temperature ionic liquid electrochemical gas sensor. To implement a miniaturized sensor with a fast response time, a three electrode system with gold interdigitated electrodes was fabricated by photolithography on a porous polytetrafluoroethylene substrate that greatly enhances gas diffusion. Furthermore, based on the reversible reaction of oxygen, a new transient double potential amperometry (DPA) was explored for electrochemical analysis to decrease the measurement time and reverse reaction by-products that could cause current drift...
April 2017: Sensors and Actuators. B, Chemical
Sebastjan Bevc, Eva Mohorko, Mitja Kolar, Polona Brglez, Andrej Holobar, Daniela Kniepeiss, Matej Podbregar, Nejc Piko, Nina Hojs, Maša Knehtl, Robert Ekart, Radovan Hojs
BACKGROUND: In a healthy individual, ammonia is converted to urea in the liver. Urea is then transported through the bloodstream and then excreted into the urine by the kidneys. In patients with chronic kidney disease (CKD), the accumulated urea is degraded by salivary urease into ammonia, which is then excreted by breathing. Breath ammonia can therefore be used for detecting the increased nitrogen-bearing wastes. In our pilot study, an electrochemical sensor was used to measure and analyze breath ammonia in healthy volunteers and patients with CKD...
June 9, 2017: Clinical Nephrology
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