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Gas sensors

Shaofeng Zhou, Shaobin Huang, Yi Li, Nannan Zhao, Han Li, Irini Angelidaki, Yifeng Zhang
This study presents an innovative microbial fuel cell-based biosensor for carbon monoxide (CO) monitoring. The hypothesis for the function of the biosensor is that CO inhibits bacterial activity in the anode and thereby reduces electricity production. A mature electrochemically active biofilm on the anode was exposed to CO gas at varied concentrations. A proportional linear relationship (R2 = 0.987) between CO concentration and voltage drop (0.8 to 24 mV) in the range of 10% and 70% of CO concentration was observed...
August 15, 2018: Talanta
Marco Abbatangelo, Estefanía Núñez-Carmona, Veronica Sberveglieri, Dario Zappa, Elisabetta Comini, Giorgio Sberveglieri
Parmigiano Reggiano cheese is one of the most appreciated and consumed foods worldwide, especially in Italy, for its high content of nutrients and taste. However, these characteristics make this product subject to counterfeiting in different forms. In this study, a novel method based on an electronic nose has been developed to investigate the potentiality of this tool to distinguish rind percentages in grated Parmigiano Reggiano packages that should be lower than 18%. Different samples, in terms of percentage, seasoning and rind working process, were considered to tackle the problem at 360°...
May 18, 2018: Sensors
Lu Lin, Peng Zhao, Andrew J Mason, Xiangqun Zeng
Electrochemical amperometric sensors require a constant or varying potential at the working electrode that drives redox reactions of the analyte for detection. The interfacial redox reaction(s) can result in the formation of new chemical products that could change the initial condition of the electrode/electrolyte interface. If the products are not inert and/or cannot be removed from the system or if the initial condition of the electrode/electrolyte interface cannot be restored, the sensor signal baseline would consequently drift which is problematic for the continuous and real-time sensors...
May 21, 2018: ACS Sensors
Neetha Rachel John, Paulose Thomas, Divya K V, Abraham K E
The study signifies a conductometric chemical sensor design using aligned Mn3O4 nanorods. Nanostructuring is an emerging field of prominence due to its capacity to introduce unprecedented properties in materials with potential applications. Hydrothermally prepared in situ Mn3O4 sample appears in urchin rod like morphology which changes to spherical shape on annealing. An aluminum anodic membrane/template (AAO) is used for the growth of the nanorods and also as a medium to support the sensor. Aligned Mn3O4nanorods are formed in the pores of AAO by vacuum infiltration approach which is later on annealed...
May 21, 2018: Nanotechnology
M Ariel Geer Wallace, Joachim D Pleil
Human breath, along with urine and blood, has long been one of the three major biological media for assessing human health and environmental exposure. In fact, the detection of odor on human breath, as described by Hippocrates in 400 BC, is considered the first analytical health assessment tool. Although less common in comparison to contemporary bio-fluids analyses, breath has become an attractive diagnostic medium as sampling is non-invasive, unlimited in timing and volume, and does not require clinical personnel...
September 18, 2018: Analytica Chimica Acta
Ashley S Reynolds, Tanya H Pierre, Rebecca McCall, Ji Wu, Worlanyo E Gato
Tin dioxide nanofibers (SnDNFs) are small fibers that have many applications. Tin dioxide nanofibers can be used in cosmetics, solar cells, toxic gas release sensors, and air pollution control. To date there have been few studies on the cytotoxicity of SnDNFs. The goal of this research is to determine if electrospun SnDNFs are toxic in a lung cancer cell line (A549). Considering the nano-scale size of the fibers, they can easily be inhaled and enter the pulmonary system and cause toxic effects in the lung. Occupational exposure to SnDNFs has been linked to pulmonary disease, making the A549 cell line important in this study...
May 18, 2018: Journal of Environmental Science and Health. Part A, Toxic/hazardous Substances & Environmental Engineering
Diana J Kelm, Jennifer L Ridgeway, Becca L Gas, Monali Mohan, David A Cook, Darlene R Nelson, Roberto P Benzo
PROBLEM: Mindfulness training includes mindfulness meditation, which has been shown to improve both attention and self-awareness. Medical providers in the intensive care unit often deal with difficult situations with strong emotions, life-and-death decisions, and both interpersonal and interprofessional conflicts. The effect of mindfulness meditation training on healthcare providers during acute care tasks such as cardiopulmonary resuscitation remains unknown. Mindfulness meditation has the potential to improve provider well-being and reduce stress in individuals involved in resuscitation teams, which could then translate into better team communication and delivery of care under stress...
May 18, 2018: Teaching and Learning in Medicine
Guo-Xia Jin, Jia Wang, Jing-Yi Liu, Jian-Ping Ma, Yu-Bin Dong
A CuI -MOF was found to be a highly selective visual sensor for recognizing C2 H2 . Gas chromatography studies indicated that it can be used to effectively remove minor amounts of C2 H2 from C2 H4 /C2 H2 mixtures (98:2) and produce highly pure C2 H4 (nearly 100%).
May 18, 2018: Inorganic Chemistry
Jianglin Ye, Huabing Tan, Shuilin Wu, Kun Ni, Fei Pan, Jie Liu, Zhuchen Tao, Yan Qu, Hengxing Ji, Patrice Simon, Yanwu Zhu
High-performance yet flexible micro-supercapacitors (MSCs) hold great promise as miniaturized power sources for increasing demand of integrated electronic devices. Herein, this study demonstrates a scalable fabrication of multilayered graphene-based MSCs (MG-MSCs), by direct laser writing (DLW) of stacked graphene films made from industry-scale chemical vapor deposition (CVD). Combining the dry transfer of multilayered CVD graphene films, DLW allows a highly efficient fabrication of large-areal MSCs with exceptional flexibility, diverse planar geometry, and capability of customer-designed integration...
May 17, 2018: Advanced Materials
Woosuck Shin, Tomoyo Goto, Daisuke Nagai, Toshio Itoh, Akihiro Tsuruta, Takafumi Akamatsu, Kazuo Sato
Inflammable breath gases such as H₂ and CH₄ are used as bio markers for monitoring the condition of the colon. However, their typical concentrations of below 100 ppm pose sensitivity and selectivity challenges to current gas sensing systems without the use of chromatography. We fabricated a compact, gas-selective thermoelectric array sensor (TAS) that uses micro-machined sensor devices with three different combustion catalysts to detect gases such as H₂, CO, and CH₄ in breath. Using Pt/Pt-W thin-film micro-heater meanders, Pd/Al₂O₃, Pt,Pd,Au/Co₃O₄, and Pt/Al₂O₃ catalysts were heated to 320, 200, and 125 °C, respectively, and the gas sensing performances of the TAS for each gas and for a model breath gas mixture of 100 ppm H₂, 25 ppm CO, 50 ppm CH₄, and 199 ppm CO₂ in air were investigated...
May 16, 2018: Sensors
Hongmei Liu, Xiaolong Li, Changmin Shi, Dongchao Wang, Li Chen, Yuanyuan He, Jianwei Zhao
The recently synthesized two-dimensional metal bis(dithiolene) complex (MDT), a kind of metal-organic framework with a kagome lattice structure, has been found to be a promising material for electronic devices. Here we report the surface adsorption effects of gas molecules on the electronic properties and transport behaviors of two-dimensional MDT (M = Fe, Co, Ni, Pd, and Pt) films. The first-principles results reveal that the MDT nanosheets are selectively sensitive to different adsorbed molecules, such as CO, NO, and O2 molecules...
May 17, 2018: Physical Chemistry Chemical Physics: PCCP
Chang-Hoon Kwak, Tae-Hyung Kim, Seong-Yong Jeong, Ji-Won Yoon, Jun-Sik Kim, Jong-Heun Lee
The chemiresistive sensing characteristics of metal oxide gas sensors depend closely on ambient humidity. Herein, we report that gas sensors using Tb-doped SnO2 yolk-shell spheres can be used for reliable acetone detection regardless of the variations in humidity. Pure SnO2 and Tb-doped SnO2 yolk-shell spheres were prepared via ultrasonic spray pyrolysis and their chemiresistive sensing characteristics were studied. The sensor resistance and gas response of the pure SnO2 yolk-shell spheres significantly changed and deteriorated upon exposure to moisture...
May 16, 2018: ACS Applied Materials & Interfaces
Nabihah Sihar, Teck Yaw Tiong, Chang Fu Dee, Poh Choon Ooi, Azrul Azlan Hamzah, Mohd Ambri Mohamed, Burhanuddin Yeop Majlis
We fabricated copper oxide nanowires (CuO NWs) ultraviolet (UV) light-assisted hydrogen gas sensor. The fabricated sensor shows promising sensor response behavior towards 100 ppm of H2 at room temperature and elevated temperature at 100 °C when exposed to UV light (3.0 mW/cm2 ). One hundred-cycle device stability test has been performed, and it is found that for sample elevated at 100 °C, the UV-activated sample achieved stability in the first cycle as compared to the sample without UV irradiation which needed about 10 cycles to achieve stability at the initial stage, whereas the sample tested at room temperature was able to stabilize with the aid of UV irradiation...
May 15, 2018: Nanoscale Research Letters
Ashvin Bashyam, Matthew Li, Michael J Cima
Single-sided NMR has the potential for broad utility and has found applications in healthcare, materials analysis, food quality assurance, and the oil and gas industry. These sensors require a remote, strong, uniform magnetic field to perform high sensitivity measurements. We demonstrate a new permanent magnet geometry, the Unilateral Linear Halbach, that combines design principles from "sweet-spot" and linear Halbach magnets to achieve this goal through more efficient use of magnetic flux. We perform sensitivity analysis using numerical simulations to produce a framework for Unilateral Linear Halbach design and assess tradeoffs between design parameters...
May 9, 2018: Journal of Magnetic Resonance
Xining Zang, Caiwei Shen, Yao Chu, Buxuan Li, Minsong Wei, Junwen Zhong, Mohan Sanghadasa, Liwei Lin
Versatile and low-cost manufacturing processes/materials are essential for the development of paper electronics. Here, a direct-write laser patterning process is developed to make conductive molybdenum carbide-graphene (MCG) composites directly on paper substrates. The hierarchically porous MCG structures are converted from fibrous paper soaked with the gelatin-mediated inks containing molybdenum ions. The resulting Mo3 C2 and graphene composites are mechanically stable and electrochemically active for various potential applications, such as electrochemical ion detectors and gas sensors, energy harvesters, and supercapacitors...
May 15, 2018: Advanced Materials
Vera Ruzsanyi, Miklós Péter Kalapos, Christine Schmidl, Daniela Karall, Sabine Scholl-Buergi, Matthias Baumann
Ketogenic diets (KD) were initially introduced to clinical practice as alimentary approaches with the aim to control drug-resistant epilepsies. Therapy control, particularly at initiation, happens through regular blood analysis and control of urine ketone levels. However, there is a lack of fast, reliable and preferably non-invasive methods of analysis. The exhaled breath contains hundreds of volatile organic compounds (VOCs), which can be modified by diet. The instrumental development of VOC detection converges in the direction of low cost sensors, which can facilitate the self-monitoring of the patients in the future if reliable breath markers are available...
May 15, 2018: Journal of Breath Research
Janghyeon Lee, Si-Hyung Lim
Breath analysis has become increasingly important as a noninvasive process for the clinical diagnosis of patients suffering from various diseases. Many commercial gas preconcentration instruments are already being used to overcome the detection limits of commercial gas sensors for gas concentrations which are as low as ~100 ppb in exhaled breath. However, commercial instruments are large and expensive, and they require high power consumption and intensive maintenance. In the proposed study, a micro gas preconcentrator (μ-PC) filled with a carbon nanotube (CNT) foam as an adsorbing material was designed and fabricated for the detection of low-concentration ethane, which is known to be one of the most important biomarkers related to chronic obstructive pulmonary disease (COPD) and asthma...
May 14, 2018: Sensors
Léonard Y M Eymann, Rosario Scopelliti, Farzaneh Fadaei Tirani, Kay Severin
Covalent adducts of imidazole-based mesoionic carbenes and nitrous oxide (N2 O, "laughing gas") can be converted into azo dyes by reaction with arenes in the presence of AlCl3 or HCl. The azo coupling can be achieved with electron-rich aromatic compounds such as mesitylene, trimethoxybenzene, azulene, or dibenzo-18-crown-6. The latter coupling reaction allows for the easy preparation of a colorimetric sensor for potassium or sodium ions. As a putative intermediate of the reaction with acid, we were able to isolate and structurally characterize a rare diazohydroxide...
May 14, 2018: Chemistry: a European Journal
Amir Hossein Alinoori, Saeed Masoum
A unique metal oxide semiconductor sensor (MOS) array detector with eight sensors was designed and fabricated in a PTFE chamber as an interface for coupling with multicapillary gas chromatography. This design consists of eight transfer lines with equal length between the multicapillary columns (MCC) and sensors. The deactivated capillary columns were passed through each transfer line and homemade flow splitter to distribute the same gas flow on each sensor. Using eight ports flow splitter design helps us to equal the length of carrier gas path and flow for each sensor, minimizing the dead volume of the sensor's chamber and increasing chromatographic resolution...
May 14, 2018: Analytical Chemistry
Ghobad Behzadi Pour, Leila Fekri Aval, Shahnaz Eslami
Background: Hydrogen sensors are micro/nano-structure that are used to locate hydrogen leaks. They are considered to have fast response/recovery time and long lifetime as compared to conventional gas sensors. In this paper, fabrication of sensitive capacitive-type hydrogen gas sensor based on Ni thin film has been investigated. The C-V curves of the sensor in different hydrogen concentrations have been reported. Method: Dry oxidation was done in thermal chemical vapor deposition furnace (TCVD)...
April 2018: Current Nanoscience
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