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Gas sensors

Peihua Zhu, Yucheng Wang, Pan Ma, Feifei Song, Xinyu Han, Shuncheng Yao, Cheng Yang
A sandwich-type (phthalocyaninato)(porphyrinato) europium double-decker complex Eu(TPyP){Pc-(OC8H17)8} [TPyP = meso-tetra(4-pyridyl)porphyrin; Pc-(OC8H17)8 = 2,3,9,10,16,17,23,24-octakis(octyloxy)phthalocyanine] (2) was designed and prepared. For comparative studies, Eu(TPyP)(Pc) (1) was also prepared. Highly ordered nanotubes of complexes 1 and 2 were successfully fabricated by using an anodized alumina oxide (AAO) template method. The nanotubes were comparatively investigated by electronic absorption spectra, scanning electron microscopy (SEM), low-angle X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and energy dispersive spectroscopy (EDS) techniques...
January 16, 2017: Dalton Transactions: An International Journal of Inorganic Chemistry
Tanmay Das, Apurba Pramanik, Debasish Haldar
Ammonia is not only a highly important gas for civilization but also contribute significantly for climate change and human health hazard. Highly sensitive ammonia sensor has been developed from a fluorescent zwitterionic spirocyclic Meisenheimer complex. Moreover, formation of this Meisenheimer complex can also be utilized for selective as well as naked eye instant detection of nitro aromatic explosive picric acid. The presence of a quaternary nitrogen atom directly attached to the spiro carbon is the unique feature of this Meisenheimer complex...
January 16, 2017: Scientific Reports
Roberto Motterlini, Roberta Foresti
Carbon monoxide (CO) is continuously produced in mammalian cells during degradation of heme. It is a stable gaseous molecule that reacts selectively with transition metals in a specific redox state and these characteristics restrict the interaction of CO with defined biological targets that transduce its signaling activity. Because of the high affinity of CO for ferrous heme, these targets can be grouped into heme-containing proteins, representing a large variety of sensors and enzymes with a series of diverse function in the cell and the organism...
January 11, 2017: American Journal of Physiology. Cell Physiology
Akash Katoch, Jae Young Park, Ho-Hyoung Kim, Dolly Rana, Deepika Jamwala
Surface area controlled porous TiO2 thin films were prepared via a simple sol-gel chemical route and their gas sensing properties were thoroughly investigated in the presence of typical oxidizing NO2 gas. The surface area of TiO2 thin films was controlled by developing porous TiO2 networked by means of controlling the TiO2-to-TTIP (titanium isopropoxide, C12H28O4Ti) molar ratio, where, TiO2 nanoparticles of size ~ 20 nm were used. The sensor's response was found to depend on the surface area of TiO2 thin films...
January 10, 2017: Nanotechnology
Daoli Zhao, Tingting Wang, Keaton Nahan, Xuefei Guo, Zhanping Zhang, Zhongyun Dong, Shuna Chen, Da-Tren Chou, Daeho Hong, Prashant N Kumta, William R Heineman
: The effect of widely different corrosion rates of Mg alloys on four parameters of interest for in vivo characterization was evaluated: (1) the effectiveness of transdermal H2 measurements with an electrochemical sensor for noninvasively monitoring biodegradation compared to the standard techniques of in vivo X-ray imaging and weight loss measurement of explanted samples, (2) the chemical compositions of the corrosion layers of the explanted samples by XPS, (3) the effect on animal organs by histology, and (4) the accumulation of corrosion by-products in multiple organs by ICP-MS...
January 6, 2017: Acta Biomaterialia
Takafumi Akamatsu, Toshio Itoh, Woosuck Shin
Mixed-potential gas sensors with a proton conductor consisting of zinc metaphosphate glass and benzimidazole were fabricated for the detection of hydrogen produced by intestinal bacteria in dry and humid air. The gas sensor consisting of an alumina substrate with platinum and gold electrodes showed good response to different hydrogen concentrations from 250 parts per million (ppm) to 25,000 ppm in dry and humid air at 100-130 °C. The sensor response varied linearly with the hydrogen and carbon monoxide concentrations due to mass transport limitations...
January 5, 2017: Sensors
Matthew S Hoehler, Christopher M Smith
This paper explores the use of blue laser triangulation sensors to measure displacement of a target located behind or in the close proximity of natural gas diffusion flames. This measurement is critical for providing high-quality data in structural fire tests. The position of the laser relative to the flame envelope can significantly affect the measurement scatter, but has little influence on the mean values. We observe that the measurement scatter is normally distributed and increases linearly with the distance of the target from the flame along the beam path...
November 2016: Measurement Science & Technology
Ameya Rao, Hu Long, Anna Harley-Trochimczyk, Thang Pham, Alex Zettl, Carlo Carraro, Roya Maboudian
A simple and versatile strategy is presented for the localized on-chip synthesis of an ordered metal oxide hollow sphere array directly on a low power microheater platform to form a closely integrated miniaturized gas sensor. Selective microheater surface modification through fluorinated monolayer self-assembly and its subsequent microheater-induced thermal decomposition enables the position-controlled deposition of an ordered two-dimensional colloidal sphere array, which serves as a sacrificial template for metal oxide growth via homogeneous chemical precipitation; this strategy ensures control in both the morphology and placement of the sensing material on only the active heated area of the microheater platform, providing a major advantage over other methods of presynthesized nanomaterial integration via suspension coating or printing...
January 13, 2017: ACS Applied Materials & Interfaces
Byung-Man Kim, Hyun-Gyu Han, Jeong Soo Kim, HyeonOh Shin, Tae-Hyuk Kwon
Dye distribution in a mesoporous TiO2 film is a key factor in the performance of dye-sensitized solar cells, but there has been little research on it. Here we report even dye distribution within the porous TiO2 film achieved by a physical driving force of gas flow. Gas-assisted dye arrangement, gas bubbling soaking (GBS), significantly accelerates the dye infiltration compared to conventional overnight soaking (OS). As a demonstration, we investigated the time-dependent dye infiltration using plasmon sensors...
January 12, 2017: ACS Applied Materials & Interfaces
Sun Young Choi, Yonghun Kim, Hee-Suk Chung, Ah Ra Kim, Jung-Dae Kwon, Jucheol Park, Young Lae Kim, Se-Hun Kwon, Myung Gwan Hahm, Byungjin Cho
Here, we report that Nb doping of two-dimensional (2D) MoSe2 layered nanomaterials is a promising approach to improve their gas sensing performance. In this study, Nb atoms were incorporated into a 2D MoSe2 host matrix, and the Nb doping concentration could be precisely controlled by varying the number of Nb2O5 deposition cycles in the plasma enhanced atomic layer deposition process. At relatively low Nb dopant concentrations, MoSe2 showed enhanced device durability as well as NO2 gas response, attributed to its small grains and stabilized grain boundaries...
January 6, 2017: ACS Applied Materials & Interfaces
Wahiduzzaman, Kelsey Allmond, John Stone, Spencer Harp, Khan Mujibur
We report the sonochemical synthesis of MOF (metal organic framework) nanoparticles of 30-200 nm in size and electrospraying of those particles on electrospun nanofibers to process a MOF-attached nanofibrous membrane. This membrane displayed significant selectivity towards CO2 and capacity of adsorbing with 4000-5000 ppm difference from a mixed gas flow of 1% CO2 and 99% N2. Applying ultrasonic waves during the MOF synthesis offered rapid dispersion and formation of crystalline MOF nanoparticles in room temperature...
December 2017: Nanoscale Research Letters
T Kim, S Kim, D Kim, S Kang, M Cho, K Kim, D Shin, Y Noh, T Suh
PURPOSE: Hard-plate based abdominal compression is known to be effective, but no explicit method exists to quantify abdominal compression force (ACF) and maintain the proper ACF through the whole procedure. In addition, even with compression, it is necessary to do 4D CT to manage residual motion but, 4D CT is often not possible due to reduced surrogating sensitivity. In this study, we developed and evaluated a system that both monitors ACF in real time and provides surrogating signal even under compression...
June 2016: Medical Physics
Po-Jen Chien, Takuma Suzuki, Masato Tsujii, Ming Ye, Koji Toma, Takahiro Arakawa, Yasuhiko Iwasaki, Kohji Mitsubayashi
Exhaled breath analysis has attracted lots of researchers attention in the past decades due to its advantages such as its non-invasive property and the possibility of continuous monitoring. In addition, several volatile organic compounds in breath have been identified as biomarkers for some diseases. Particularly, studies have pointed out that concentration of isopropanol (IPA) in exhaled air might relate with certain illnesses such as liver disease, chronic obstructive pulmonary (COPD), and lung cancer. In this study, a highly sensitive and selective biochemical gas sensor (bio-sniffer) for the breath IPA concentration determination was constructed and optimized...
December 22, 2016: Biosensors & Bioelectronics
Joon Hyub Kim, Min-Jung Song, Ki Beom Kim, Joon-Hyung Jin, Nam Ki Min
The effect of cleaning the surface of single-walled carbon nanotube (SWNT) networks by thermal and the O₂ plasma treatments is presented in terms of NH₃ gas sensing characteristics. The goal of this work is to determine the relationship between the physicochemical properties of the cleaned surface (including the chemical composition, crystal structure, hydrophilicity, and impurity content) and the sensitivity of the SWNT network films to NH₃ gas. The SWNT networks are spray-deposited on pre-patterned Pt electrodes, and are further functionalized by heating on a programmable hot plate or by O₂ plasma treatment in a laboratory-prepared plasma chamber...
December 30, 2016: Sensors
Ya-Nan Zhang, Qilu Wu, Huijie Peng, Yong Zhao
A highly-sensitive and temperature-robust photonic crystal fiber (PCF) modal interferometer coated with Pd/WO3 film was fabricated and studied, aiming for real-time monitoring of dissolved hydrogen concentration in transformer oil. The sensor probe was fabricated by splicing two segments of a single mode fiber (SMF) with both ends of the PCF. Since the collapse of air holes in the PCF in the interfaces between SMF and PCF, a SMF-PCF-SMF interferometer structure was formed. The Pd/WO3 film was fabricated by sol-gel method and coated on the surface of the PCF by dip-coating method...
December 2016: Review of Scientific Instruments
Juan Sun, Hao Deng, Ningwu Liu, Hongliang Wang, Benli Yu, Jingsong Li
We developed a laser absorption sensor based on a pulsed, broadband tunable external cavity quantum cascade laser (ECQCL) centered at 1285 cm(-1). Unlike traditional infrared spectroscopy system, a quartz crystal tuning fork (QCTF) as a light detector was used for laser signal detection. Fast Fourier transform was applied to extract vibration intensity information of QCTF. The sensor system is successfully tested on nitrous oxide (N2O) spectroscopy measurements and compared with a standard infrared detector...
December 2016: Review of Scientific Instruments
Tingwei Gu, Deren Kong, Jian Jiang, Fei Shang, Jing Chen
This paper applies back propagation neural network (BPNN) optimized by genetic algorithm (GA) for the prediction of pressure generated by a drop-weight device and the quasi-static calibration of piezoelectric high-pressure sensors for the measurement of propellant powder gas pressure. The method can effectively overcome the slow convergence and local minimum problems of BPNN. Based on test data of quasi-static comparison calibration method, a mathematical model between each parameter of drop-weight device and peak pressure and pulse width was established, through which the practical quasi-static calibration without continuously using expensive reference sensors could be realized...
December 2016: Review of Scientific Instruments
Alvaro Ortiz Pérez, Vera Kallfaß-de Frenes, Alexander Filbert, Janosch Kneer, Benedikt Bierer, Pirmin Held, Philipp Klein, Jürgen Wöllenstein, Dirk Benyoucef, Sigrid Kallfaß, Ulrich Mescheder, Stefan Palzer
This manuscript describes the design considerations, implementation, and laboratory validation of an odor sensing module whose purpose is to support people that suffer from incontinence. Because of the requirements expressed by the affected end-users the odor sensing unit is realized as a portable accessory that may be connected to any pre-existing smart device. We have opted for a low-cost, low-power consuming metal oxide based gas detection approach to highlight the viability of developing an inexpensive yet helpful odor recognition technology...
December 29, 2016: Sensors
Pedro Castillero, Javier Roales, Tânia Lopes-Costa, Juan R Sánchez-Valencia, Angel Barranco, Agustín R González-Elipe, José M Pedrosa
Open porous and transparent microcolumnar structures of TiO₂ prepared by physical vapour deposition in glancing angle configuration (GLAD-PVD) have been used as host matrices for two different fluorescent cationic porphyrins, 5-(N-methyl 4-pyridyl)-10,15,20-triphenyl porphine chloride (MMPyP) and meso-tetra (N-methyl 4-pyridyl) porphine tetrachloride (TMPyP). The porphyrins have been anchored by electrostatic interactions to the microcolumns by self-assembly through the dip-coating method. These porphyrin/TiO₂ composites have been used as gas sensors for ammonia and amines through previous protonation of the porphyrin with HCl followed by subsequent exposure to the basic analyte...
December 23, 2016: Sensors
Jin-Chern Chiou, Chin-Cheng Wu, Yu-Chieh Huang, Shih-Cheng Chang, Tse-Mei Lin
This study examined the performance of a flexible polymer/multi-walled carbon nanotube (MWCNT) composite sensor array as a function of operating temperature. The response magnitudes of a cost-effective flexible gas sensor array equipped with a heater were measured with respect to five different operating temperatures (room temperature, 40 °C, 50 °C, 60 °C, and 70 °C) via impedance spectrum measurement and sensing response experiments. The selected polymers that were droplet cast to coat a MWCNT conductive layer to form two-layer polymer/MWCNT composite sensing films included ethyl cellulose (EC), polyethylene oxide (PEO), and polyvinylpyrrolidone (PVP)...
December 22, 2016: Sensors
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