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Gas sensors

A S M Iftekhar Uddin, Usman Yaqoob, Gwiy-Sang Chung
Herein we report an enhanced triboelectric nanogenerator (TENG) based on the contact-separation mode between a patterned film of polydimethylsiloxane (PDMS) with a semi-metallic elastomer of poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) and a nylon fiber film. The addition of ethylene glycol to the PEDOT:PSS film improves the functionality of the TENG significantly, yielding promising applicability in both indoor and outdoor (i.e., under sunlight) environments, with the maximum instantaneous power of 0...
October 21, 2016: ACS Applied Materials & Interfaces
Da Huang, Zhi Yang, Xiaolin Li, Liling Zhang, Jing Hu, Yanjie Su, Nantao Hu, Guilin Yin, Dannong He, Yafei Zhang
Graphene is an ideal candidate for gas sensing due to its excellent conductivity and large specific surface areas. However, it usually suffers from sheet stacking, which seriously debilitates its sensing performance. Herein, we demonstrate a three-dimensional conductive network based on stacked SiO2@graphene core-shell hybrid frameworks for enhanced gas sensing. SiO2 spheres are uniformly encapsulated by graphene oxide (GO) through an electrostatic self-assembly approach to form SiO2@GO core-shell hybrid frameworks, which are reduced through thermal annealing to establish three-dimensional (3D) conductive sensing networks...
October 20, 2016: Nanoscale
Richard L Pyle, Raymond Boland, Holly Bolick, Brian W Bowen, Christina J Bradley, Corinne Kane, Randall K Kosaki, Ross Langston, Ken Longenecker, Anthony Montgomery, Frank A Parrish, Brian N Popp, John Rooney, Celia M Smith, Daniel Wagner, Heather L Spalding
Although the existence of coral-reef habitats at depths to 165 m in tropical regions has been known for decades, the richness, diversity, and ecological importance of mesophotic coral ecosystems (MCEs) has only recently become widely acknowledged. During an interdisciplinary effort spanning more than two decades, we characterized the most expansive MCEs ever recorded, with vast macroalgal communities and areas of 100% coral cover between depths of 50-90 m extending for tens of km(2) in the Hawaiian Archipelago...
2016: PeerJ
Xin Xiao, Xue-Feng Cheng, Xiang Hou, Jing-Hui He, Qing-Feng Xu, Hua Li, Na-Jun Li, Dong-Yun Chen, Jian-Mei Lu
An organic thin-film gas sensor based on squaraine detects ammonia as low as 40 ppb with impressive reversibility and stability. The resonance-stabilized zwitterionic characteristics offer squaraines high affinity and sensitivity toward electron-rich analytes without irreversible chemical binding, while the embedded squaric ring makes SA-CH3 highly sensitive. The symmetric molecular geometry and good crystallinity also contribute to the high performance.
October 18, 2016: Small
Marco Sturaro, Enrico Della Gaspera, Niccolò Michieli, Carlo Cantalini, Seyed Mahmoud Emamjomeh, Massimo Guglielmi, Alessandro Martucci
Highly doped wide band gap metal oxides nanocrystals have recently been proposed as building blocks for applications as transparent electrodes, electrochromics, plasmonics, and optoelectronics in general. Here we demonstrate the application of gallium doped zinc oxide (GZO) nanocrystals as novel plasmonic and chemiresistive sensors for the detection of hazardous gases including hydrogen (H2) and nitrogen dioxide (NO2). GZO nanocrystals with a tunable surface plasmon resonance in the near infrared are obtained using a colloidal heat-up synthesis...
October 18, 2016: ACS Applied Materials & Interfaces
Yuxiang Qin, Yongyao Wang, Yi Liu, Xiaojuan Zhang
The limited surface area and compacted configuration of silicon nanowires (SiNWs), which are made by one-step metal-assisted chemical etching (MACE) go against target gas diffusion and adsorbtion for gas sensing application. To harvest suitable gas sensitivity and fast response-recovery characteristics, an aligned, rough SiNW array with loose configuration and high surface area was fabricated by a two-step etching process. The MACE technique was first employed to fabricate a smooth SiNW array, and then a KOH post-etching method was developed to roughen the NW surface further...
October 17, 2016: Nanotechnology
Anandram Venkatasubramanian, Vincent T K Sauer, Swapan K Roy, Mike Xia, David S Wishart, Wayne K Hiebert
Micro-Gas Chromatography (GC) is promising for portable chemical analysis. We demonstrate a nano-optomechanical system (NOMS) as an ultrasensitive mass detector in gas chromatography. Bare, native oxide, silicon surfaces are sensitive enough to monitor volatile organic compounds at ppm levels, while simultaneously demonstrating chemical selectivity. The NOMS is able to sense GC peaks from derivatized metabolites at physiological concentrations. This is an important milestone for small-molecule quantitation assays in next generation metabolite analyses for applications such as disease diagnosis and personalized medicine...
October 17, 2016: Nano Letters
Chung-Hsuan Wu, Wei-Han Wang, Chien-Chong Hong, Kuo Chu Hwang
This paper presents a novel disposable breath-sensing tube with an on-tube single-nanowire (NW) sensor array for noninvasive, simple, and on-site detection of exhaled breath biomarkers. Although various noninvasive detection methods for lung cancer biomarkers in breath samples exist, they are unsuitable for self-diagnostics and immediate detection because they entail complicated handling procedures and are time intensive. In this study, we simulated, fabricated, and characterized disposable nanosensors by using single TiO2 and Ag NWs in flexible plastic tubes...
October 14, 2016: Lab on a Chip
Liwei Wang, Jintao Li, Yinghui Wang, Kefu Yu, Xingying Tang, Yuanyuan Zhang, Shaopeng Wang, Chaoshuai Wei
One-dimensional (1D) SnO2-coated ZnO nanowire (SnO2/ZnO NW) N-N heterojunctions were successfully constructed by an effective solvothermal treatment followed with calcination at 400 °C. The obtained samples were characterized by means of XRD, SEM, TEM, Scanning TEM coupled with EDS and XPS analysis, which confirmed that the outer layers of N-type SnO2 nanoparticles (avg. 4 nm) were uniformly distributed onto our pre-synthesized n-type ZnO nanowire supports (diameter 80~100 nm, length 12~16 μm). Comparisons of the gas sensing performances among pure SnO2, pure ZnO NW and the as-fabricated SnO2/ZnO NW heterojunctions revealed that after modification, SnO2/ZnO NW based sensor exhibited remarkably improved response, fast response and recovery speeds, good selectivity and excellent reproducibility to n-butylamine gas, indicating it can be used as promising candidates for high-performance organic amine sensors...
October 13, 2016: Scientific Reports
Ali Aldalbahi, Peter Feng, Norah Alhokbany, Eida Al-Farraj, Saad M Alshehri, Tansir Ahamad
Functionalized (MWCNTs-COOH), non-functionalized multiwalled carbon nanotubes (MWCNTs) and polyaniline (PANI) based conducting nanocomposites (PANI/polymer/MWCNTs and PANI/polymer/MWCNTs-COOH) have been prepared in polymer matrix. The prepared nanocomposites were characterized via FTIR, TGA, Raman spectroscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM) and X-ray diffraction (XRD). It was observed that the prepared conducting nanocomposites show excellent sensing performances toward CH4 at room temperature and both the response and recovery time were recorded at around 5s, respectively, at the room...
September 12, 2016: Spectrochimica Acta. Part A, Molecular and Biomolecular Spectroscopy
Yarrow Madrona, Christopher A Waddling, Paul R Ortiz de Montellano
DosS is a sensor in Mycobacterium tuberculosis that differentially responds to O2, NO, and CO, as well as to changes in the redox state of the prosthetic heme iron atom. The ferrous protein and its Fe(II)NO and Fe(II)CO complexes undergo autophosphorylation and subsequently transfer the phosphate group to DosR, a nuclear factor, to activate it. In contrast, autophosphorylation is negligible with the ferric protein and the Fe(II)O2 complex. To clarify the basis for this differential response to gases, we have determined the crystal structures of the NO and COcomplexes of the DosS GAF-A domain, which contains the heme to which the gases bind...
October 8, 2016: Archives of Biochemistry and Biophysics
L F Weissert, J A Salmond, G Miskell, M Alavi-Shoshtari, S K Grange, G S Henshaw, D E Williams
Ozone (O3) concentrations in urban areas are spatially and temporally variable, influenced by chemical production, depletion through deposition and chemical titration processes and dispersion. To date, analysis of intra-urban variability of O3 concentrations, and the influence of local controls on production and depletion rates, has been limited due to the low spatial and/or temporal resolution of measurements. We demonstrate that measurements made using a carefully managed multi-sensor network of low-cost gas-sensitive semiconductor instruments are sufficiently precise to resolve subtle but significant variations in ozone concentration across a region...
October 8, 2016: Science of the Total Environment
Leimiao Lin, Dong Liu, Qiaofen Chen, Hongzhi Zhou, Jianmin Wu
Novel chemiresistive gas sensors based on a vertical tip-tip contact silicon nanowire (TTC-SiNW) array were constructed. The welding of TTC-SiNWs after joule heating treatment was confirmed by a current-voltage curve (I-V curve). The TTC-SiNW structure not only resolved the problem of electrode contact encountered in conventional nanowire sensors, but also elongated the nanowire length to increase the void space for fast gas diffusion. The TTC-SiNW sensor comprising the same two types of SiNW arrays responded to NO2 very sensitively...
October 7, 2016: Nanoscale
Fengdong Qu, Huifang Jiang, Minghui Yang
The rational design of nanoscale metal oxides with hollow structures and tunable porosity has stimulated tremendous attention due to their vital importance for practical applications. Here, we report the designed synthesis of ZnO/ZnCo2O4 hollow core-shell nanocages (HCSNCs) through a metal-organic framework (MOF) route. The strategy includes the synthesis of a zeolite imidazolate framework-8 (ZIF-8)/Co-Zn hydroxide core-shell nanostructure precursor and subsequent transformation to ZnO/ZnCo2O4 HCSNCs by thermal annealing of the as-prepared precursor in air...
September 15, 2016: Nanoscale
Xiaoxing Zhang, Lei Yu, Xiaoqing Wu, Weihua Hu
A gas sensor is used to detect SF6 decomposed gases, which are related to insulation faults, to accurately assess the insulated status of electrical equipment. Graphene films (GrF) modified with Au nanoparticles are used as an adsorbent for the detection of H2S and SOF2, which are two characteristic products of SF6 decomposed gases. Sensing experiments are conducted at room temperature. Results demonstrate that Au-modified GrF yields opposite responses to the tested gases and is thus considered a promising material for developing H2S- and SOF2-selective sensors...
November 2015: Advanced Science (Weinheim, Baden-Wurttemberg, Germany)
Atef Thamri, Hamdi Baccar, Claudia Struzzi, Carla Bittencourt, Adnane Abdelghani, Eduard Llobet
The chemical modification of multiwalled carbon nanotubes (MWCNTs) with a long chain mercapto acid is reported as a way to improve sensitivity and response time of gas sensors for detecting alcohols, acetone and toxic gases such as DMMP. We have developed sensors employing MWCNTs decorated with gold nanoparticles and modified with a 16-mercaptohexadecanoic acid (MHDA) monolayer. Morphological and compositional analysis by Transmission Electron Microscopy (TEM), Fourier Transform Infra-red Spectroscopy (FTIR) and X-ray photoelectron spectroscopy were performed to characterize the gold nanoparticles and to check the bonding of the thiol monolayer...
October 10, 2016: Scientific Reports
Hyelynn Song, Taewoo Kim, Hyeongwook Im, Raquel Ovalle-Robles, Tae June Kang, Yong Hyup Kim
A carbon nanotube (CNT) sheet nanogenerator that does not require any liquid or gas flow for power generation is developed on the basis of Coulombic interactions, making the device attractive as a building block for self-powered sensors. The working principle of the CNT nanogenerator is probed in terms of sweeping speed, distance between charged object and nanotube sheet, surface charge, and number of layers of nanotube sheet. The nature of the CNT sheet and its formation process is such that simply winding the CNT sheet stripe n times around a substrate leads to increasing the power n times...
September 22, 2016: Nanoscale
Nguyen Duc Chinh, Nguyen Duc Quang, Hyundong Lee, Truong Thi Hien, Nguyen Minh Hieu, Dahye Kim, Chunjoong Kim, Dojin Kim
In2O3 nanostructure sensors were fabricated by arc-discharging a source composed of a graphite tube containing indium. The NO gas sensing properties, as well as the morphology, structure, and electrical properties, were examined at room temperature under UV light illumination. In particular, the response and recovery kinetics of the sensor at room temperature under various UV light intensities were studied. The maximum response signal was observed at an intermediate UV light intensity, which could be corroborated by a nano-size effect based on the conduction model of a resistive chemical nano sensor...
October 7, 2016: Scientific Reports
Colin R Andrew, Olga N Petrova, Isabelle Lamarre, Jean-Christophe Lambry, Fabrice Rappaport, Michel Negrerie
Nitric oxide (NO) sensors are heme proteins which may also bind CO and O2. Control of heme-gas affinity and their discrimination are achieved by the structural properties and reactivity of the heme and its distal and proximal environments, leading to several energy barriers. In the bacterial NO-sensor cytochrome c' from Alcaligenes xylosoxidans (AXCP), the single Leu16Ala distal mutation boosts the affinity for gas ligands by a remarkable 106-108-fold, transforming AXCP from one of the lowest affinity gas binding proteins to one of the highest...
October 6, 2016: ACS Chemical Biology
John Joseph Keating, Joseph Imbrogno, Georges Belfort
The fundamentals and applications of polymer brush modified membranes are reviewed. This new class of synthetic membranes is explored with an emphasis on tuning the membrane performance through polymer brush grafting. This work highlights the intriguing performance characteristics of polymer brush modified membranes in a variety of separations. Polymer brushes are a versatile and effective means in designing membranes for applications in protein adsorption and purification, colloid stabilization, sensors, water purification, pervaporation of organic compounds, gas separations, and as stimuli responsive materials...
October 6, 2016: ACS Applied Materials & Interfaces
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