scholarly journals Reducing Humidity Response of Gas Sensors for Medical Applications: Use of Spark Discharge Synthesis of Metal Oxide Nanoparticles

Sensors ◽  
2018 ◽  
Vol 18 (8) ◽  
pp. 2600 ◽  
Author(s):  
Alexey Vasiliev ◽  
Andrey Varfolomeev ◽  
Ivan Volkov ◽  
Nikolay Simonenko ◽  
Pavel Arsenov ◽  
...  
Keyword(s):  
Metal Oxide ◽  
Gas Sensors ◽  
Tin Dioxide ◽  
Early Stage ◽  
Sno2 Nanoparticles ◽  
Metal Oxide Nanoparticles ◽  
Sol Gel ◽  
Spark Discharge ◽  
Hydroxyl Groups ◽  
Enteric Infection

The application of gas sensors in breath analysis is an important trend in the early diagnostics of different diseases including lung cancer, ulcers, and enteric infection. However, traditional methods of synthesis of metal oxide gas-sensing materials for semiconductor sensors based on wet sol-gel processes give relatively high sensitivity of the gas sensor to changing humidity. The sol-gel process leading to the formation of superficial hydroxyl groups on oxide particles is responsible for the strong response of the sensing material to this factor. In our work, we investigated the possibility to synthesize metal oxide materials with reduced sensitivity to water vapors. Dry synthesis of SnO2 nanoparticles was implemented in gas phase by spark discharge, enabling the reduction of the hydroxyl concentration on the surface and allowing the production of tin dioxide powder with specific surface area of about 40 m2/g after annealing at 610 °C. The drop in sensor resistance does not exceed 20% when air humidity increases from 40 to 100%, whereas the response to 100 ppm of hydrogen is a factor of 8 with very short response time of about 1 s. The sensor response was tested in mixtures of air with hydrogen, which is the marker of enteric infections and the marker of early stage fire, and in a mixture of air with lactate (marker of stomach cancer) and ammonia gas (marker of Helicobacter pylori, responsible for stomach ulcers).

scholarly journals Gas Sensor with Reduced Humidity Response Based on Metal Oxide Nanoparticles Synthesized by Spark Discharge

2018 ◽  
Vol 34 (2) ◽  
pp. 648-654 ◽  
Author(s):  
Alexey Vasiliev ◽  
Andrey Varfolomeev ◽  
Ivan Volkov ◽  
Pavel Arsenov ◽  
Alexey Efimov ◽  
...  
Keyword(s):  
Metal Oxide ◽  
Gas Sensor ◽  
Metal Oxide Nanoparticles ◽  
Spark Discharge ◽  
Oxide Nanoparticles ◽  
Humidity Response

scholarly journals Effect of Nanoparticles on Wettability of Nanocoating on Carbon Steel

2016 ◽  
Vol 1 (2) ◽  
pp. 71-74
Author(s):  
Norhasnidawani Johari ◽  
Noor Azlina Hassan ◽  
Norita Hassan ◽  
Mohd Hanafi Ani
Keyword(s):  
Contact Angle ◽  
Carbon Steel ◽  
Metal Oxide ◽  
Water Drop ◽  
Metal Oxide Nanoparticles ◽  
Sol Gel ◽  
Hydrophobic Surface ◽  
Oxide Nanoparticles ◽  
Water Medium ◽  
Wetting Ability

Nanocoatings plays an important role in coating industry. The solution was being prepared through copolymerization of epoxy resin hardener and with the incorporation of metal oxide nanoparticles, Zinc Oxide (ZnO) and Silica (SiO2). ZnO and SiO2 were synthesized using sol-gel. Epoxy hardener acted as host while the metal oxide nanoparticles as guest components. The formulation of nanocoatings with excellent adhesion strength and corrosion protection of carbon steel was studied. The performance of wetting ability with different medium was analysed using contact angle. Water medium showed the addition of 3wt% of hybrid between ZnO and SiO2 was the best nanocoating to form hydrophobic surface and was also the best nanocoating surface to form hydrophilic surface with vacuum oil dropping. In oil dropping, the contact angle was smaller than 90° and the water drop tends to spreads on surface.

Enhanced selectivity of target gas molecules through a minimal array of gas sensors based on nanoparticle-decorated SWCNTs

The Analyst ◽  
2019 ◽  
Vol 144 (13) ◽  
pp. 4100-4110 ◽  
Author(s):  
Sonia Freddi ◽  
Giovanni Drera ◽  
Stefania Pagliara ◽  
Andrea Goldoni ◽  
Luigi Sangaletti
Keyword(s):  
Metal Oxide ◽  
Gas Sensor ◽  
Gas Sensors ◽  
Metal Oxide Nanoparticles ◽  
Sensor Arrays ◽  
Oxide Nanoparticles ◽  
Gas Molecules ◽  
Enhanced Selectivity ◽  
Gas Sensor Arrays

Layers of CNTs decorated with metal and metal–oxide nanoparticles can be used to develop highly selective gas sensor arrays.

Metal Oxide Nanocrystals: Building Blocks for Mesostructures and Precursors for Metal Nitrides

2007 ◽  
Vol 1007 ◽  
Author(s):  
Markus Niederberger ◽  
Jelena Buha ◽  
Igor Djerdj
Keyword(s):  
Metal Oxide ◽  
Metal Oxide Nanoparticles ◽  
Sol Gel ◽  
Building Blocks ◽  
Formation Mechanisms ◽  
Oxide Nanoparticles ◽  
Metal Nitride ◽  
Ordered Mesoporous Materials ◽  
Crystallite Sizes ◽  
The One

ABSTRACTSol-gel routes to metal oxide nanoparticles in organic solvents under exclusion of water represent a valuable alternative to aqueous methods. In comparison to the complex aqueous chemistry, nonaqueous processes offer the possibility to better understand and to control the reaction pathways on a molecular level, enabling the synthesis of nanomaterials with high crystallinity and well-defined and uniform particle morphologies. The manifold role of the organic species in providing the oxygen for the oxide formation and in controlling the crystal growth and the assembly properties makes it possible to tailor the morphological, structural and compositional characteristics of the final inorganic products.In addition to metal oxides with nearly spherical crystallite sizes in the range of just a few nanometers, also more complex morphologies such as nanowire bundles, nanorods or lamellar organic-inorganic hybrids of varying hierarchical complexity can be achieved in one step and without the use of any surfactants. The spherical nanocrystallites are on the one hand versatile building blocks for the fabrication of fully crystalline and ordered mesoporous materials and on the other hand suitable precursors for the synthesis of metal nitride nanoparticles.This proceeding provides an overview of the various oxidic nanoparticles synthesized via the nonaqueous and surfactant-free sol-gel approach, summarizes the most frequently found formation mechanisms, and offers some insight into the crystallization pathway of nanoparticles. Furthermore, the use of metal oxide nanoparticles as nanobuilding blocks for the preparation of nano- and mesostructures as well as their transformation into metal nitride nanocrystals will be discussed.

Applications of Nanostructured Materials as Gas Sensors

2013 ◽  
Vol 201 ◽  
pp. 131-158 ◽  
Author(s):  
Ravi Chand Singh ◽  
Manmeet Pal Singh ◽  
Hardev Singh Virk
Keyword(s):  
Metal Oxide ◽  
Gas Sensors ◽  
Tin Dioxide ◽  
Gas Sensing ◽  
Dominant Role ◽  
Low Cost ◽  
Critical Role ◽  
Health And Safety ◽  
Chemical Route ◽  
Metal Oxide Sensors

Gas detection instruments are increasingly needed for industrial health and safety, environmental monitoring, and process control. To meet this demand, considerable research into new sensors is underway, including efforts to enhance the performance of traditional devices, such as resistive metal oxide sensors, through nanoengineering. The resistance of semiconductors is affected by the gaseous ambient. The semiconducting metal oxides based gas sensors exploit this phenomenon. Physical chemistry of solid metal surfaces plays a dominant role in controlling the gas sensing characteristics. Metal oxide sensors have been utilized for several decades for low-cost detection of combustible and toxic gases. Recent advances in nanomaterials provide the opportunity to dramatically increase the response of these materials, as their performance is directly related to exposed surface volume. Proper control of grain size remains a key challenge for high sensor performance. Nanoparticles of SnO2have been synthesized through chemical route at 5, 25 and 50°C. The synthesized particles were sintered at 400, 600 and 800°C and their structural and morphological analysis was carried out using X-ray diffraction (XRD) and transmission electron microscopy (TEM). The reaction temperature is found to be playing a critical role in controlling nanostructure sizes as well as agglomeration. It has been observed that particle synthesized at 5 and 50°C are smaller and less agglomerated as compared to the particles prepared at 25°C. The studies revealed that particle size and agglomeration increases with increase in sintering temperature. Thick films gas sensors were fabricated using synthesized tin dioxide powder and sensing response of all the sensors to ethanol vapors was investigated at different temperatures and concentrations. The investigations revealed that sensing response of SnO2nanoparticles is size dependent and smaller particles display higher sensitivity. Table of Contents

Metal Oxide Nanoparticles as Novel Gate Materials for Field-Effect Gas Sensors

2006 ◽  
Vol 21 (3) ◽  
pp. 275-278 ◽  
Author(s):  
S. Roy ◽  
A. Salomonsson ◽  
A. Lloyd Spetz ◽  
C. Aulin ◽  
P.-O. Käll ◽  
...  
Keyword(s):  
Metal Oxide ◽  
Gas Sensors ◽  
Field Effect ◽  
Metal Oxide Nanoparticles ◽  
Oxide Nanoparticles

scholarly journals Semiconductor Sensor With Loaded SnO2 Nanoparticles For Early Warning Of Indoor Fires

2019 ◽  
Vol Vol. 14, No.1 ◽  
pp. 37-42 ◽  
Author(s):  
Nelly Maksymovyc ◽  
Ludmila Oleksenko ◽  
Georgiy Fedorenko ◽  
Ganna Arinarkhova ◽  
Keyword(s):  
Early Warning ◽  
Tin Dioxide ◽  
Sno2 Nanoparticles ◽  
Sol Gel ◽  
Average Particle Size ◽  
High Sensitivity ◽  
Average Particle ◽  
Sensitive Layer ◽  
Semiconductor Sensor ◽  
Wide Range

Nanosized tin dioxide material with an average particle size of 10-11 nm was prepared by a sol-gel method. The material has been tested as a gas sensitive layer of a semiconductor sensor. Platinum was introduced into the gas sensitive layer to increase the sensor response to hydrogen. It was shown that the Pt-containing sensor has high sensitivity to hydrogen: its electrical resistance changes in 9.2 times in the presence of 22 ppm H2 in air. It was demonstrated that the sensor applicable to a wide range of H2 measurements in air (3-935 ppm) and has a fast dynamic response. The sensor demonstrates rather good reproducibility of its signal to H2 and withstands hydrogen overload (935 ppm) without a loss of its sensitivity to H2 microconcentration (22 ppm). The results are prospective for applying the sensor in the detectors for early warning of indoor fires.

scholarly journals Adsorption-Semiconductor Sensor Based on Nanosized SnO2 for Early Warning of Indoor Fires

2021 ◽  
Author(s):  
Nelli Maksymovych ◽  
Ludmila Oleksenko ◽  
George Fedorenko
Keyword(s):  
Tin Dioxide ◽  
Early Stage ◽  
Dynamic Properties ◽  
Sol Gel ◽  
Average Particle Size ◽  
High Sensitivity ◽  
Average Particle ◽  
Semiconductor Sensor ◽  
Wide Range

The paper is devoted for a solution of indoors fires prevention at early stage by determination of H2 (fire precursor gas) in air using a semiconductor sensor. A material based on Pt-containing nanosized tin dioxide with an average particle size of 10–11 nm obtained via a sol–gel method was created for a gas sensitive layer of the sensor. The developed sensor has high sensitivity to H2 micro concentration, a wide range of its detectable content in air, selectivity of H2 measuring in the presence of СО and СН4, good dynamic properties. The combination of these properties is very important for prevention of inflammations on their early stages before the open fires appearance. Economic benefit of the proposed sensor is due to a lower cost and higher reliability of the fire situation detection.

scholarly journals Adsorption Behavior of Trace Beryllium (II) onto Metal Oxide Nanoparticles Dispersed in Water

2017 ◽  
Vol 9 (4) ◽  
pp. 62 ◽  
Author(s):  
Shoichi Katsuta ◽  
Naoki Kanaya ◽  
Kotaro Bessho ◽  
Hideaki Monjushiro
Keyword(s):  
Metal Oxide ◽  
Ph Dependence ◽  
Metal Oxide Nanoparticles ◽  
Cooling Water ◽  
High Energy ◽  
Adsorption Behavior ◽  
Oxide Surface ◽  
Oxide Nanoparticles ◽  
Hydroxyl Groups ◽  
Radioactive Trace

Radioactive trace 7Be produced in cooling water systems for high-energy accelerators is known to be captured by metal-oxide colloidal nanoparticles generated through corrosion of metal components in water. This study is aimed at investigating the adsorption behavior of trace Be2+ onto various oxide nanoparticles (Al2O3, SiO2, TiO2, Fe2O3, CoO, and CuO) dispersed in water at 25 °C in order to clarify the tendency and features of the interaction of Be2+ with metal oxides. From pH dependence of the distribution ratio of Be2+ between the nanoparticle phase and the aqueous solution phase, the surface complexation constants (βs,n) have been determined for the reaction of Be2+ with the hydroxyl groups on the oxide surface (>S−OH), i.e., Be2+ + n >S−OH ⇄ (>S−O)nBe(2−n)+ + n H+. The n values are generally 1 and 2 and the sequences of the βs,n values are Fe2O3 > TiO2 » Al2O3 > SiO2 for βs,1 and Fe2O3 > TiO2 > SiO2 > Al2O3 >> CoO » CuO for βs,2. The dependences of the the βs,n values on the kind of oxide are explained based on the electronegativity of the metal (or Si) composing the oxide.

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