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Gas sensors

Maoxiang Hou, Feng Zhu, Ying Wang, Yiping Wang, Changrui Liao, Shen Liu, Peixiang Lu
A gas pressure sensor based on an antiresonant reflecting guidance mechanism in a hollow-core fiber (HCF) with an open microchannel is experimentally demonstrated for gas pressure sensing. The microchannel was created on the ring cladding of the HCF by femtosecond laser drilling to provide an air-core pressure equivalent to the external environment. The HCF cladding functions as an antiresonant reflecting waveguide, which induces sharp periodic lossy dips in the transmission spectrum. The proposed sensor exhibits a high pressure sensitivity of 3...
November 28, 2016: Optics Express
Wangyang Fu, Lin Jiang, Erik P van Geest, Lia M C Lima, Grégory F Schneider
Recent research trends now offer new opportunities for developing the next generations of label-free biochemical sensors using graphene and other two-dimensional materials. While the physics of graphene transistors operated in electrolyte is well grounded, important chemical challenges still remain to be addressed, namely the impact of the chemical functionalizations of graphene on the key electrical parameters and the sensing performances. In fact, graphene - at least ideal graphene - is highly chemically inert...
November 29, 2016: Advanced Materials
Ramesh Ghosh, P K Giri
Semiconductor nanowires (NWs), in particular Si NWs, have attracted much attention in the last decade for their unique electronic properties and potential applications in several emerging areas. With the introduction of heterostructures (HSs) on NWs, new functionalities are obtained and the device performance is improved significantly in many cases. Due to the easy fabrication techniques, excellent optoelectronic properties and compatibility of forming HSs with different inorganic/organic materials, Si NW HSs have been utilized in various configurations and device architectures...
November 28, 2016: Nanotechnology
Jin Zhang, Qin Zhu, Yumin Zhang, Zhongqi Zhu, Qingju Liu
The single-walled carbon nanotube (SWCNT)-molecularly imprinted powder (MIP) composites in this paper were prepared by mixing SWCNTs with MIPs. The structure and micrograph of the as-prepared SWCNTs-MIPs samples were characterized by XRD and TEM. The gas-sensing properties were tested through indirect-heating sensors based on SWCNT-MIP composites fabricating on an alumina tube with Au electrodes and Pt wires. The results showed that the structure of SWCNTs-MIPs is of orthogonal perovskite and the average particle size of the SWCNTs-MIPs was in the range of 10-30 nm...
December 2016: Nanoscale Research Letters
Bora Karasulu, René H J Vervuurt, Wilhelmus M M Kessels, Ageeth A Bol
Integrating metals and metal oxides with graphene is key in utilizing its extraordinary material properties that are ideal for nanoelectronic and catalyst applications. Atomic layer deposition (ALD) has become a key technique for depositing ultrathin, conformal metal(oxide) films. ALD of metal(oxide) films on graphene, however, remains a genuine challenge due to the chemical inertness of graphene. In this study we address this issue by combining first-principles density functional theory (DFT) simulations with ALD experiments...
December 1, 2016: Nanoscale
Sheng Cheng, Jiangbo Lu, Dong Han, Ming Liu, Xiaoli Lu, Chunrui Ma, Shengbai Zhang, Chonglin Chen
Giant optical transmittance changes of over 300% in wide wavelength range from 500 nm to 2500 nm were observed in LaBaCo2O5.5+δ thin films annealed in air and ethanol ambient, respectively. The reduction process induces high density of ordered oxygen vacancies and the formation of LaBaCo2O5.5 (δ = 0) structure evidenced by aberration-corrected transmission electron microscopy. Moreover, the first-principles calculations reveal the origin and mechanism of optical transmittance enhancement in LaBaCo2O5...
November 23, 2016: Scientific Reports
Yucheng Wang, Pan Ma, Feifei Song, Shuncheng Yao, Changlong Chen, Peihua Zhu
In the present study, the nanotubes of 5-(4-hydroxyphenyl)-10, 15, 20-tri(4-chlorophenyl) porphyrin (p-HTClPP) (1) and 5-(4-hydroxyphenyl)-10, 15, 20-tri(4-chlorophenyl) porphyrin cobalt (p-HTClPPCo) (2) were successfully prepared by using anodize alumina oxide (AAO) template method. The p-HTClPP and p-HTClPPCo nanotubes have been confirmed by scanning electron microscopy (SEM), transmission electron microscopy (TEM), electronic absorption spectra, fluorescence spectroscopy, fourier transform infrared spectroscopy (FT-IR), low-angle X-ray diffraction (XRD) and energy dispersive spectroscopy (EDS) techniques...
November 9, 2016: Journal of Colloid and Interface Science
Chuan Wu, Guojun Wen, Lei Han, Xiaoming Wu
The measurement of wellbore annulus gas-liquid two-phase flow in CBM (coalbed methane) wells is of great significance for reasonably developing gas drainage and extraction processes, estimating CBM output, judging the operating conditions of CBM wells and analyzing stratum conditions. Hence, a specially designed sensor is urgently needed for real-time measurement of gas-liquid two-phase flow in CBM wellbore annulus. Existing flow sensors fail to meet the requirements of the operating conditions of CBM wellbore annulus due to such factors as an inapplicable measurement principle, larger size, poor sealability, high installation accuracy, and higher requirements for fluid media...
November 18, 2016: Sensors
Detlef Lazik, Pramit Sood
Linear membrane-based gas sensors that can be advantageously applied for the measurement of a single gas component in large heterogeneous systems, e.g., for representative determination of CO₂ in the subsurface, can be designed depending on the properties of the observation object. A resulting disadvantage is that the permeation-based sensor response depends on operating conditions, the individual site-adapted sensor geometry, the membrane material, and the target gas component. Therefore, calibration is needed, especially of the slope, which could change over several orders of magnitude...
November 17, 2016: Sensors
Nhan Ai Tran, Fu-Ming Pan, Jeng-Tzong Sheu
Double-junction n(+)/n(-)/n(+) polysilicon nanobelts featuring selectively deposited sensing materials have been investigated for application as H2 gas sensors. The selective modification of the devices was performed through a combination of localized ablation of a resist and lift-off of a previous catalyst material deposited through e-beam evaporation. Four nanobelt devices, differentiated by their doping concentrations at the n(-) region (from 2.5 × 10(13) to 2.5 × 10(14) cm(-2)), were analyzed in terms of the responses to H2 and their self-heating effects...
December 16, 2016: Nanotechnology
Yongjun Bae, Peter V Pikhitsa, Hyesung Cho, Mansoo Choi
Multifurcated assemblies composed of charged nanoparticles (NPs) are fabricated by using spark discharge and manipulating the electric field. The multifurcated structure of the assembly of NPs and spontaneous interconnections between the near structures are described. The gas sensor with the tetrafurcated-NP-assembled structure demonstrates ≈200% enhanced response to 100 ppm CO at 300 °C.
November 10, 2016: Advanced Materials
R B M Aggio, P White, H Jayasena, B de Lacy Costello, N M Ratcliffe, C S J Probert
BACKGROUND: Inflammatory bowel disease and irritable bowel syndrome may present in a similar manner. Measuring faecal calprotectin concentration is often recommended to rule out inflammatory bowel disease, however, there are no tests to positively diagnose irritable bowel syndrome and invasive tests are still used to rule out other pathologies. AIM: To investigate a platform technology for diagnosing inflammatory bowel disease and irritable bowel syndrome based on faecal gas...
January 2017: Alimentary Pharmacology & Therapeutics
Zhenzhou Cheng, Keisuke Goda
We present waveguide-integrated graphene devices for photonic gas sensing. In a gas environment, graphene's conductivity is changed by adsorbed gas molecules which serve as charge-carrier donors or acceptors. To accurately probe gas-induced variations in the graphene's conductivity, we optimize the graphene's Fermi level and spectral region. Then, we propose graphene-on-silicon and graphene-on-germanium suspended membrane slot waveguides in which propagating light in the waveguide has a strong interaction with the top graphene layer...
December 16, 2016: Nanotechnology
Mary Ortmayer, Pierre Lafite, Binuraj R K Menon, Tewes Tralau, Karl Fisher, Lukas Denkhaus, Nigel S Scrutton, Stephen E J Rigby, Andrew W Munro, Sam Hay, David Leys
The universal Per-ARNT-Sim (PAS) domain functions as a signal transduction module involved in sensing diverse stimuli such as small molecules, light, redox state and gases. The highly evolvable PAS scaffold can bind a broad range of ligands, including haem, flavins and metal ions. However, although these ligands can support catalytic activity, to our knowledge no enzymatic PAS domain has been found. Here we report characterization of the first PAS enzyme: a haem-dependent oxidative N-demethylase. Unrelated to other amine oxidases, this enzyme contains haem, flavin mononucleotide, 2Fe-2S and tetrahydrofolic acid cofactors, and specifically catalyses the NADPH-dependent oxidation of dimethylamine...
November 16, 2016: Nature
Yi Liu, Yanli Li, Pengcheng Huang, Han Song, Gang Zhang
To detect hydrogen gas leakage rapidly, many types of hydrogen sensors containing palladium alloy film have been proposed and fabricated to date. However, the mechanisms and factors that determine the response rate of such hydrogen sensor have not been established theoretically. The manners in which response time is forecasted and sensitive film is designed are key issues in developing hydrogen sensors with nanometer film. In this paper, a unilateral diffusion model of hydrogen atoms in Pd alloy based on Fick's second law is proposed to describe the Pd-H reaction process...
November 15, 2016: Scientific Reports
Toshio Itoh, Toshio Miwa, Akihiro Tsuruta, Takafumi Akamatsu, Noriya Izu, Woosuck Shin, Jangchul Park, Toyoaki Hida, Takeshi Eda, Yasuhiro Setoguchi
Various volatile organic compounds (VOCs) in breath exhaled by patients with lung cancer, healthy controls, and patients with lung cancer who underwent surgery for resection of cancer were analyzed by gas condenser-equipped gas chromatography-mass spectrometry (GC/MS) for development of an exhaled breath monitoring prototype system involving metal oxide gas sensors, a gas condenser, and gas chromatography columns. The gas condenser-GC/MS analysis identified concentrations of 56 VOCs in the breath exhaled by the test population of 136 volunteers (107 patients with lung cancer and 29 controls), and selected four target VOCs, nonanal, acetoin, acetic acid, and propanoic acid, for use with the condenser, GC, and sensor-type prototype system...
November 10, 2016: Sensors
Xingchen Dong, Xiaoxing Zhang, Xiaoqing Wu, Hao Cui, Dachang Chen
Latent insulation defects introduced in manufacturing process of gas-insulated switchgears can lead to partial discharge during long-time operation, even to insulation fault if partial discharge develops further. Monitoring of decomposed components of SF₆, insulating medium of gas-insulated switchgear, is a feasible method of early-warning to avoid the occurrence of sudden fault. Polyaniline thin-film with protonic acid deposited possesses wide application prospects in the gas-sensing field. Polyaniline thin-film sensors with only sulfosalicylic acid deposited and with both hydrochloric acid and sulfosalicylic acid deposited were prepared by chemical oxidative polymerization method...
November 10, 2016: Sensors
Patrycja Suchorska-Woźniak, Olga Rac, Marta Fiedot, Helena Teterycz
The article presents the results of the detection of low-concentration C1-C4 alcohols using a planar sensor, in which a sepiolite filter was applied next to the gas-sensitive layer based on tin dioxide. The sepiolite layer is composed of tubes that have a length of several microns, and the diameter of the single tube ranges from several to tens of nanometers. The sepiolite layer itself demonstrated no chemical activity in the presence of volatile organic compounds (VOC), and the passive filter made of this material did not modify the chemical composition of the gaseous atmosphere diffusing to the gas-sensitive layer...
November 9, 2016: Sensors
Hao Zhang, Yuan Cen, Yu Du, Shuangchen Ruan
ZnO/graphene (ZnO-G) hybrid composites are prepared via hydrothermal synthesis with graphite, N-methyl-pyrrolidone (NMP), and Zn(NO₃)₂·6H₂O as the precursors. The characterizations, including X-ray diffraction (XRD), thermogravimetric analyses (TGA), Raman spectroscopy, and transmission electron microscopy (TEM) indicate the formation of ZnO-G. Gas sensors were fabricated with ZnO-G composites and ZnO as sensing material, indicating that the response of the ZnO towards acetone was significantly enhanced by graphene doping...
November 9, 2016: Sensors
Wei Li, Zhilin Feng, Enwen Dai, Jie Xu, Gang Bai
Here, a silicon nanopillar array (Si-NPA) was fabricated. It was studied as a room-temperature organic vapour sensor, and the ethanol and acetone gas sensing properties were detected with I-V curves. I-V curves show that these Si-NPA gas sensors are sensitive to ethanol and acetone organic vapours. The turn-on threshold voltage is about 0.5 V and the operating voltage is 3 V. With 1% ethanol gas vapour, the response time is 5 s, and the recovery time is 15 s. Furthermore, an evaluation of the gas sensor stability for Si-NPA was performed...
November 9, 2016: Sensors
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