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Gas sensors

Stefanie Kamann, Olivier Aerts, Lutz Heinemann
In the past decade, new diabetes technologies, including continuous glucose monitoring (CGM) systems, support patients with diabetes in their daily struggle with achieving a good glucose control. However, shortly after the first CGM systems appeared on the market, also the first concerns about adverse skin reactions were raised. Most patients claimed to suffer from (sometimes severe) skin irritation, or even allergy, which they related to the (acrylate-based) adhesive part of the device. For a long time the actual substance that caused these skin reactions with, for example, the Flash Glucose Monitoring system (iscCGM; Freestyle® Libre) could not be identified; however, recently Belgian and Swedish dermatologists reported that the majority of their patients that have developed a contact-allergic while using iscCGM react sensitively to a specific acrylate, that is, isobornyl acrylate (IBOA)...
March 1, 2018: Journal of Diabetes Science and Technology
Enrico Della Gaspera, Enrico Menin, Gianluigi Maggioni, Cinzia Sada, Alessandro Martucci
Sub-monolayers of monodisperse Au colloids with different surface coverage have been embedded in between two different metal oxide thin films, combining sol-gel depositions and proper substrates functionalization processes. The synthetized films were TiO₂, ZnO, and NiO. X-ray diffraction shows the crystallinity of all the oxides and verifies the nominal surface coverage of Au colloids. The surface plasmon resonance (SPR) of the metal nanoparticles is affected by both bottom and top oxides: in fact, the SPR peak of Au that is sandwiched between two different oxides is centered between the SPR frequencies of Au sub-monolayers covered with only one oxide, suggesting that Au colloids effectively lay in between the two oxide layers...
March 14, 2018: Materials
Vijendra Singh Bhati, Sapana Ranwa, Saravanan Rajamani, Kusum Kumari, Ramesh Raliya, Pratim Biswas, Mahesh Kumar
We report enhanced hydrogen gas sensing performance of Ni doped ZnO sensor decorated with optimum concentration of reduced graphene oxide (rGO). Ni doped ZnO nanoplates were grown by the radio frequency (RF) sputtering, rGO was synthesized by Hummer's method and decorated by drop cast method of various concentration of rGO (0- 1.5 wt%). Current- voltage characteristics of rGO loaded sensor is highly influenced by loading concentration of rGO where current conduction decreases and sensor resistance increases as rGO concentration is increased up to 0...
March 14, 2018: ACS Applied Materials & Interfaces
Hoa Thanh Phan, Thien Xuan Dinh, Phong Nhu Bui, Van Thanh Dau
In this paper, we report on the design, simulation, and experimental analysis of a miniaturized device that can generate multiple circulated jet flows. The device is actuated by a lead zirconate titanate (PZT) diaphragm. The flows in the device were studied using three-dimensional transient numerical simulation with the programmable open source OpenFOAM and was comparable to the experimental result. Each flow is verified by two hotwires mounted at two positions inside each consisting chamber. The experiment confirmed that the flow was successfully created, and it demonstrated good agreement with the simulation...
March 13, 2018: Sensors
Shawana Tabassum, Liang Dong, Ratnesh Kumar
We present an effective yet simple approach to study the dynamic variations in optical properties (such as the refractive index (RI)) of graphene oxide (GO) when exposed to gases in the visible spectral region, using the thin-film interference method. The dynamic variations in the complex refractive index of GO in response to exposure to a gas is an important factor affecting the performance of GO-based gas sensors. In contrast to the conventional ellipsometry, this method alleviates the need of selecting a dispersion model from among a list of model choices, which is limiting if an applicable model is not known a priori...
March 5, 2018: Optics Express
Masanori Ando, Vasudevanpillai Biju, Yasushi Shigeri
Ozone (O3 ) gas is widely used as a strong oxidizing agent for many purposes, such as the decomposition/removal of organic contaminants and photoresist, and the deodorization/disinfection of air and water. However, ozone is highly toxic to the human body when the air concentration exceeds about 1 ppm. Therefore, there is increasing demand for simple, sensitive, reliable, and cost-effective techniques for sensing ozone gas. This article describes the features, advantages, and disadvantages of the available, practical techniques for sensing ozone gas in ambient air...
2018: Analytical Sciences: the International Journal of the Japan Society for Analytical Chemistry
Zhe Li, Pinggang Jia, Guocheng Fang, Hao Liang, Ting Liang, Wenyi Liu, Jijun Xiong
Using arc discharge technology, we fabricated a fiber-optic Fabry-Perot (FP) pressure sensor with a very low temperature coefficient based on a microbubble that can be applied in a high-temperature environment. The thin-walled microbubble can be fabricated by heating the gas-pressurized hollow silica tube (HST) using a commercial fusion splicer. Then, the well-cut single-mode fiber (SMF) was inserted into the microbubble, and they were fused together. Thus, the FP cavity can be formed between the end of the SMF and the inner surface of the microbubble...
March 10, 2018: Applied Optics
Chaeeun Kim, Jun-Cheol Park, Sun Young Choi, Yonghun Kim, Seung-Young Seo, Tae-Eon Park, Se-Hun Kwon, Byungjin Cho, Ji-Hoon Ahn
2D layered materials with sensitive surfaces are promising materials for use in chemical sensing devices, owing to their extremely large surface-to-volume ratios. However, most chemical sensors based on 2D materials are used in the form of laterally defined active channels, in which the active area is limited to the actual device dimensions. Therefore, a novel approach for fabricating self-formed active-channel devices is proposed based on 2D semiconductor materials with very large surface areas, and their potential gas sensing ability is examined...
March 9, 2018: Small
Kyoung Ha Cha, Xuewei Wang, Mark E Meyerhoff
Over the last three decades, there has been extensive interest in developing in vivo chemical sensors that can provide real-time measurements of blood gases (oxygen, carbon dioxide, and pH), glucose/lactate, and potentially other critical care analytes in the blood of hospitalized patients. However, clot formation with intravascular sensors and foreign body response toward sensors implanted subcutaneously can cause inaccurate analytical results. Further, the risk of bacterial infection from any sensor implanted in the human body is another major concern...
December 2017: Applied Materials Today
Cláudia Nunes, Manuel A Coimbra, Paula Ferreira
Chitosan-based functional materials are emerging for food applications. The covalent bonding of molecular entities demonstrates to enhance resistance to the typical acidity of food assigning mechanical and moisture/gas barrier properties. Moreover, the grafting to chitosan of some functional molecules, like phenolic compounds or essential oils, gives antioxidant, antimicrobial, among others properties to chitosan. The addition of nanofillers to chitosan and other biopolymers improves the already mentioned required properties for food applications and can attribute electrical conductivity and magnetic properties for active and intelligent packaging...
March 8, 2018: Chemical Record: An Official Publication of the Chemical Society of Japan ... [et Al.]
Tian-Tian Li, Na Bao, Ai-Fang Geng, Hui Yu, Ying Yang, Xiang-Ting Dong
For the first time, ordered mesoporous ZnO nanoparticles have been synthesized by a template method. The electroplating after chemical plating method was creatively used to form copper film on the surface of the prepared ZnO, and then a CuO film-decorated ordered porous ZnO composite (CuO/ZnO) was obtained by a high-temperature oxidation method. In2 O3 was loaded into the prepared CuO film-ZnO by an ultrasonic-assisted method to sensitize the room temperature gas-sensing performance of the prepared CuO/ZnO materials...
February 2018: Royal Society Open Science
Margot P Bickler, Laura J Rhodes
Detecting life-threatening common dyshemoglobins such as carboxyhemoglobin (COHb, resulting from carbon monoxide poisoning) or methemoglobin (MetHb, caused by exposure to nitrates) typically requires a laboratory CO-oximeter. Because of cost, these spectrophotometer-based instrument are often inaccessible in resource-poor settings. The aim of this study was to determine if an inexpensive pocket infrared spectrometer and smartphone (SCiO®Pocket Molecular Sensor, Consumer Physics Ltd., Israel) accurately detects COHb and MetHb in single drops of blood...
2018: PloS One
Zhuo Chen, Jinrong Wang, Douxing Pan, Yao Wang, Richard Noetzel, Hao Li, Peng Xie, Wenle Pei, Ahmad Umar, Lei Jiang, Nan Li, Nicolaas Frans de Rooij, Guofu Zhou
Inspired by the densely covered capillary structure inside a dog's nose, we report an artificial nanostructure, i. e., poly(sodium p-styrenesulfonate)-functionalized reduced graphene oxide nanoscrolls (PGNS), with high structural perfection and efficient gas sensing applications. A facile supramolecular assembly is introduced to functionalize graphene with the functional polymer, combined with the lyophilization technique to massively transform the planar graphene-based nanosheets to nanoscrolls. Detailed characterizations reveal that the bioinspired nanoscrolls exhibit a wide-open tubular morphology with uniform dimensions that is structurally distinct from the previously reported ones...
March 7, 2018: ACS Nano
Charalampos Drosos, Dimitra Vernardou
Vanadium (IV) oxide (VO₂) layers have received extensive interest for applications in smart windows to batteries and gas sensors due to the multi-phases of the oxide. Among the methods utilized for their growth, chemical vapour deposition is a technology that is proven to be industrially competitive because of its simplicity when performed at atmospheric pressure (APCVD). APCVD's success has shown that it is possible to create tough and stable materials in which their stoichiometry may be precisely controlled...
March 5, 2018: Materials
Xinyuan Zhou, Liping Yang, Yuzhi Bian, Xiang Ma, Ning Han, Yunfa Chen
Nowadays, the detection of low concentration combustible methane gas has attracted great concern. In this paper, a coupling p+n field effect transistor (FET) amplification circuit is designed to detect methane gas. By optimizing the load resistance ( RL ), the response to methane of the commercial MP-4 sensor can be magnified ~15 times using this coupling circuit. At the same time, it decreases the limit of detection (LOD) from several hundred ppm to ~10 ppm methane, with the apparent response of 7.0 ± 0.2 and voltage signal of 1...
March 6, 2018: Sensors
Tiening Jin, Junchao Zhou, Zelun Wang, Ricardo Gutierrez-Osuna, Charles Ahn, Wonjun Hwang, Ken Park, Pao Tai Lin
Real-time gas analysis on-a-chip was demonstrated using a mid-infrared (mid-IR) microcavity. Optical apertures for the microcavity were made of ultrathin silicate membranes embedded in a silicon chip using the complementary metal-oxide-semiconductor (CMOS) process. Fourier transform infrared spectroscopy (FTIR) shows that the silicate membrane is trans-parent in the range 2.5 - 6.0 µm, a region that overlaps with multiple characteristic gas absorption lines and therefore enables gas detection applications...
March 6, 2018: Analytical Chemistry
Niharendu Mahapatra, Avi Ben-Cohen, Yonathan Vaknin, Alex Henning, Joseph Hayon, Klimentiy Anatoliy Shimanovich, Hayit Greenspan, Yossi Rosenwaks
For the past several decades, there is a growing demand for the development of low-power gas sensing technology for the selective detection of volatile organic compounds (VOCs), important for monitoring safety, pollution and healthcare. Here we report the selective detection of homologous alcohols and different functional groups containing VOCs using the electrostatically formed nanowire (EFN) sensor without any surface modification of the device. Selectivity towards specific VOC is achieved by training machine-learning based classifiers using the calculated changes in the threshold voltage and the drain-source on current, obtained from systematically controlled biasing of the surrounding gates (junction and back gates) of the field-effect transistors (FET)...
March 6, 2018: ACS Sensors
Vjekoslav Kokoric, Johannes Theisen, Andreas Wilk, Christophe Penisson, Gabriel Bernard, Boris Mizaikoff, Jean-Christophe Paul Gabriel
A microfluidic system combined with substrate-integrated hollow waveguide (iHWG) vapor phase infrared spectroscopy has been developed for evaluating the chemical activity of volatile compounds dissolved in complex fluids. Chemical activity is an im-portant yet rarely exploited parameter in process analysis and control. Access to chemical activity parameters enables systematic studies on phase diagrams of complex fluids, the detection of aggregation processes, etc.. The instrumental approach developed herein uniquely enables controlled evaporation/permeation from a sample solution into a hollow waveguide structure, and analyz-ing the partial pressures of volatile constituents...
March 5, 2018: Analytical Chemistry
Ana T S Semeano, Daniele F Maffei, Susana Palma, Rosamaria W C Li, Bernadette D G M Franco, Ana C A Roque, Jonas Gruber
As consumption of fish and fish-based foods increases, non-destructive monitoring of fish freshness also becomes more prominent. Fish products are very perishable and prone to microbiological growth, not always easily detected by organoleptic evaluation. The analysis of the headspace of fish specimens through gas sensing is an interesting approach to monitor fish freshness. Here we report a gas sensing method for monitoring Tilapia fish spoilage based on the application of a single gas sensitive gel material coupled to an optical electronic nose...
July 2018: Food Control
Arno Laesecke, Karsten Meier, Richard F Hafer
The viscosity of 1,1,1-trifluoroethane (R143a) was measured with a piezoelectrically actuated, torsionally vibrating quartz sensor. The measurements extended over a temperature range from 300 K to 440 K with pressures to 68 MPa and covered states from the dilute gas to the compressed liquid. The influence of the drive voltage on the torsional displacement of the vibrator in fluid and in vacuum was systematically investigated. Since R143a is highly polar, the sample conductance and susceptance were also monitored with the sensor to detect possible electroviscous contributions in the measured viscosities...
February 2018: Journal of Molecular Liquids
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