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Gas sensors

James E Ellis, Dan C Sorescu, Seth C Burkert, David L White, Alexander Star
Melon, a polymeric, uncondensed graphitic carbon nitride with a two-dimensional structure has been coupled with reduced graphene oxide (rGO) to create an oxygen chemiresistor sensor that is active under UV photoactivation. Oxygen gas is an important sensor target in a variety of areas including industrial safety, combustion process monitoring, as well as environmental and biomedical fields. Due to the intimate electrical interface formed between melon and rGO, charge transfer of photoexcited electrons occurs between the two materials when under UV (λ=365 nm) irradiation...
July 24, 2017: ACS Applied Materials & Interfaces
Akihito Miyamoto, Sungwon Lee, Nawalage Florence Cooray, Sunghoon Lee, Mami Mori, Naoji Matsuhisa, Hanbit Jin, Leona Yoda, Tomoyuki Yokota, Akira Itoh, Masaki Sekino, Hiroshi Kawasaki, Tamotsu Ebihara, Masayuki Amagai, Takao Someya
Thin-film electronic devices can be integrated with skin for health monitoring and/or for interfacing with machines. Minimal invasiveness is highly desirable when applying wearable electronics directly onto human skin. However, manufacturing such on-skin electronics on planar substrates results in limited gas permeability. Therefore, it is necessary to systematically investigate their long-term physiological and psychological effects. As a demonstration of substrate-free electronics, here we show the successful fabrication of inflammation-free, highly gas-permeable, ultrathin, lightweight and stretchable sensors that can be directly laminated onto human skin for long periods of time, realized with a conductive nanomesh structure...
July 17, 2017: Nature Nanotechnology
Ileana Andreea Ratiu, Victor Bocos-Bintintan, Adrian Patrut, Victor Hugo Moll, Matthew Turner, C L Paul Thomas
The objective of our study was to investigate whether one may quickly and reliably discriminate different microorganism strains by direct monitoring of the headspace atmosphere above their cultures. Headspace samples above a series of in vitro bacterial cultures were directly interrogated using an aspiration type ion mobility spectrometer (a-IMS), which produced distinct profiles ("fingerprints") of ion currents generated simultaneously by the detectors present inside the ion mobility cell. Data processing and analysis using principal component analysis showed net differences in the responses produced by volatiles emitted by various bacterial strains...
August 22, 2017: Analytica Chimica Acta
Stamatios Giannoukos, Alan Marshall, Stephen Taylor, Jeremy Smith
The synthetic generation/coding and transmission of olfactory information over a gas stream or an odor network is a new and unexplored field. Application areas vary from the entertainment or advertisement industry to security and telemedicine. However, current technological limitations frustrate the accurate reproduction of decoded and transmitted olfactory data. This study describes the development, testing, and characterization of a novel odor emitter (OE) that is used to investigate the generation-encoding of gaseous standards with odorous characteristics with a regulatable way, for scent transmission purposes...
July 21, 2017: Journal of the American Society for Mass Spectrometry
Hao Kan, Min Li, Zhilong Song, Sisi Liu, Baohui Zhang, Jingyao Liu, Ming-Yu Li, Guangzu Zhang, ShengLin Jiang, Huan Liu
Low dimensional nanomaterials have emerged as candidates for gas sensors owing to their unique size-dependent properties. In this paper, Bi2S3 nanobelts were synthesized via a facile solvothermal process and spin-coated onto alumina substrates at room temperature. The conductometric devices can even sensitively response to the relatively low concentrations of NO2 at room temperature, and their sensing performance can be effectively enhanced by the ligand exchange treatment with inorganic salts. The Pb(NO3)2-treated device exhibited superior sensing performance of 58...
July 5, 2017: Journal of Colloid and Interface Science
Cristina Redondo, Victor Srougi, José Batista da Costa, Mohammed Baghdad, Guillermo Velilla, Igor Nunes-Silva, Sebastien Bergerat, Silvia Garcia-Barreras, François Rozet, Alexandre Ingels, Marc Galiano, Rafael Sanchez-Salas, Eric Barret, Xavier Cathelineau
INTRODUCTION AND OBJECTIVE: Focal cryotherapy emerged as an efficient option to treat favorable and localized prostate cancer (PCa). The purpose of this video is to describe the procedure step by step. MATERIALS AND METHODS: We present the case of a 68 year-old man with localized PCa in the anterior aspect of the prostate. RESULTS: The procedure is performed under general anesthesia, with the patient in lithotomy position. Briefly, the equipament utilized includes the cryotherapy console coupled with an ultrasound system, argon and helium gas bottles, cryoprobes, temperature probes and an urethral warming catheter...
July 20, 2017: International Braz J Urol: Official Journal of the Brazilian Society of Urology
Nicola Charlotte Grant Black, Chenguang Liu, Ruth Pearce, Bing Li, Stefan Maier, Lesley F Cohen, John C Gallop, Ling Hao
We report a non-contact CVD graphene gas sensing method that utilises a high Q microwave dielectric resonator perturbation technique. A graphene sample is coupled to the evanescent field of a dielectric resonator whereupon nitrogen dioxide (NO2), a p-doping gas, is detected by monitoring the change in the linewidth and frequency of the resonant mode. The resonant peak shape is dependent on the number of carriers in the graphene sheet. Therefore, the linewidth perturbation can be converted to a measurement of the graphene sheet resistance...
July 20, 2017: Nanotechnology
Christoph Willa, Alexander Schmid, Danick Briand, Jiayin Yuan, Dorota Koziej
We report a light, flexible, and low-power poly(ionic liquid)/alumina composite CO2 sensor. We monitor the direct-current resistance changes as a function of CO2 concentration and relative humidity and demonstrate fast and reversible sensing kinetics. Moreover, on the basis of the alternating-current impedance measurements we propose a sensing mechanism related to proton conduction and gas diffusion. The findings presented herein will promote the development of organic/inorganic composite CO2 gas sensors. In the future, such sensors will be useful for numerous practical applications ranging from indoor air quality control to the monitoring of manufacturing processes...
July 20, 2017: ACS Applied Materials & Interfaces
Hendrik Schlicke, Malte Behrens, Clemens J Schröter, Gregor T Dahl, Hauke Hartmann, Tobias Vossmeyer
We report a novel approach for the detection of volatile compounds employing electrostatically driven drumhead resonators as sensing elements. The resonators are based on freestanding membranes of alkanedithiol cross-linked gold nanoparticles (GNPs), which are able to sorb analytes from the gas phase. Under reduced pressure, the fundamental resonance frequency of a resonator is continuously monitored while the device is exposed to varying partial pressures of toluene, 4-methylpentan-2-one, 1-propanol, and water...
April 28, 2017: ACS Sensors
Liang-Yu Chang, Ming-Yen Chuang, Hsiao-Wen Zan, Hsin-Fei Meng, Chia-Jung Lu, Ping-Hung Yeh, Jian-Nan Chen
In this work, we successfully demonstrate a fast method to determine the fish freshness by using a sensing system containing an ultrasensitive amine gas sensor to detect the volatile amine gas from the raw fish meat. When traditional titration method takes 4 h and complicated steps to test the total volatile basic nitrogen (TVB-N) as a worldwide standard for fish freshness, our sensor takes 1 min to deliver an electrical sensing response that is highly correlated with the TVB-N value. When detecting a fresh fish with a TVB-N as 18 mg/100 g, the sensor delivers an effective ammonia concentration as 100 ppb...
April 28, 2017: ACS Sensors
Chong Wang, Xueying Kou, Ning Xie, Lanlan Guo, Yanfeng Sun, Xiaohong Chuai, Jian Ma, Peng Sun, Yue Wang, Geyu Lu
Indium tungsten oxide ellipsoidal nanospheres were prepared with different In/W ratios by using a simple hydrothermal method without any surfactant for the first time. Sensors based on different In/W ratios samples were fabricated, and one of the samples exhibited better response to methanol compared with others. High content of defective oxygen (Ov) and proper output proportion of In to W might be the main reasons for the better gas sensing properties. The length of the nanosphere was about 150-200 nm, and the width was about 100 nm...
May 26, 2017: ACS Sensors
Steffen Gralert Sveegaard, Michael Nielsen, Mikkel Holmen Andersen, Kurt Vesterager Gothelf
A current challenge for development of amperometric sensors for the greenhouse gas nitrous oxide (N2O) is their sensitivity toward dioxygen and trace water. The need for aqueous dioxygen scavengers in front of the sensor implies a background signal from penetrating water vapor. In this paper, we introduce substituted phosphines as dioxygen scavengers and demonstrate the application in a dioxygen-insensitive N2O sensor. Suitably substituted phosphines have been synthesized to achieve good solubility properties in the electrochemically inert solvent propylene carbonate...
May 26, 2017: ACS Sensors
Xiaowei Li, Mya Le Thai, Rajen K Dutta, Shaopeng Qiao, Girija T Chandran, Reginald M Penner
Palladium (Pd) nanoparticle (NP)-decorated carbon nanotube (CNT) ropes (or CNT@PdNP) are used as the sensing element for hydrogen gas (H2) chemiresistors. In spite of the fact that Pd NPs have a mean diameter below 6 nm and are highly dispersed on the CNT surfaces, CNT@PdNP ropes produce a relative resistance change 20-30 times larger than is observed at single, pure Pd nanowires. Thus, CNT@PdNP rope sensors improve upon all H2 sensing metrics (speed, dynamic range, and limit-of-detection), relative to single Pd nanowires which heretofore have defined the state-of-the-art in H2 sensing performance...
February 24, 2017: ACS Sensors
Ravi Mohan Prasad, Stefan Lauterbach, Hans-Joachim Kleebe, Odile Merdrignac-Conanec, Nicolae Barsan, Udo Weimar, Aleksander Gurlo
We report on the influence of oxygen impurities on the gas sensing properties of gallium nitride (GaN) chemiresistors. As shown by XRD, elemental analysis, and TEM characterization, surface oxidation of GaN-for example, upon contact to ambient air atmosphere-creates an oxidative amorphous layer which provides the sites for the sensing toward CO. Treating this powder under dry ammonia at 800 °C converts the oxide layer in nitride, and consequently the sensing performance toward CO is dramatically reduced for ammonia treated GaN gas sensors...
June 23, 2017: ACS Sensors
Benjamin Paschke, Achim Wixforth, Dmytro Denysenko, Dirk Volkmer
Observation of the kinetics and measurement of the activation energies for gas diffusion in porous materials requires very fast and sensitive sensors. In this work, thin films of metal-organic frameworks (MOFs) with different pore sizes are grown on a surface acoustic wave (SAW) substrate, resulting in very sensitive and specific sensor systems for the detection of various gases at very short time scales. Using specially designed SAW delay lines for the detection, up to 200-nm-wide cubic MOF crystals were grown directly from a solution on the sensitive sensor chip area...
June 23, 2017: ACS Sensors
Deborah K Pallotti, Luca Passoni, Felice Gesuele, Pasqualino Maddalena, Fabio Di Fonzo, Stefano Lettieri
We demonstrate exceptionally large modulation of PL intensity in hierarchical titanium dioxide (TiO2) nanostructures exposed to molecular oxygen (O2). Optical responsivities up to about 1100% at 20% O2 concentrations are observed in hyperbranched anatase-phase hierarchical structures, outperforming those obtainable by commercial TiO2 nanopowders (up to a factor of ∼7 for response to synthetic air) and significantly improving the ones typically reported in PL-based opto-chemical gas sensing using MOXs. The improved PL response is discussed in terms of the specific morphology of hierarchical structures, characterized by simultaneous presence of small nanoparticles, large surface areas, and large voids...
January 27, 2017: ACS Sensors
Hong-Cheng Xia, Xiang-Hong Xu, Qin-Hua Song
The detection of highly toxic chemicals in a convenient, fast, and reliable manner is essential for coping with serious threats to humankind and public security caused by unexpected terrorist attacks and industrial accidents. In this paper, a highly selective fluorescent probe has been constructed through o-phenylenediamine covalently linking to coumarin (o-Pac), which can respond to phosgene in turn-on fluorescence mode. The response time is less than 0.5 min and the detection limit is as low as 3 nM in solutions...
January 27, 2017: ACS Sensors
Soo-Yeon Cho, Hyeong-Jun Koh, Hae-Wook Yoo, Jong-Seon Kim, Hee-Tae Jung
Controlling the charge concentrations of two-dimensional (2D) materials is a critical requirement for realizing versatility and potential application of these materials in high-performance electronics and sensors. In order to exploit the novel chemical-sensing characteristics of 2D materials for sensitive and selective sensors, various functionalization methods are needed to ensure efficient doping of channels based on 2D materials. In the present study, the gas-sensing performance of MoS2 has been significantly enhanced by controlled Au nanoparticle functionalization...
January 27, 2017: ACS Sensors
Dattatray S Dhawale, Tanaji Pralhad Gujar, Chandrakant D Lokhande
The development of highly sensitive and selective semiconductor based metal oxide sensor devices to detect toxic, ex-plosive, flammable and pollutant gases is still a challenging research topic. In the present work, we systematically en-hanced the liquefied petroleum gas (LPG) sensing performance of chemical bath deposited (CBD) TiO2 nanorods by decorating Pd nanoparticle catalyst. Surface morphology with elemental mapping, crystal structure, composition and oxidation states and surface area measurements of pristine TiO2 and Pd:TiO2 nanorods were examined by high resolu-tion transmission electron microscopy (HR-TEM) equipped with an EDS detector, X-ray diffraction (XRD), X-ray pho-toelectron spectroscopy (XPS) and nitrogen adsorption-desorption characterization techniques...
July 18, 2017: Analytical Chemistry
Incheol Cho, Kyungnam Kang, Daejong Yang, Jeonghoon Yun, Inkyu Park
We have developed highly sensitive, low power gas sensors through the novel integration method of porous SnO2 nanotubes (NTs) on a micro-electro-mechanical-systems (MEMS) platform. As a template material, ZnO nanowires (NWs) were directly synthesized on beam-shaped, suspended microheaters through in-situ localized hydrothermal reaction induced by local thermal energy around the Joule-heated area. Also, liquid phase deposition (LPD) process enabled the formation of porous SnO2 thin film on the surface of ZnO NWs and simultaneous etching of ZnO core, eventually to generate porous SnO2 NTs...
July 17, 2017: ACS Applied Materials & Interfaces
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