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Stella Vallejos - One of the best experts on this subject based on the ideXlab platform.
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aerosol assisted cvd grown pdo nanoparticle decorated tungsten oxide nanoneedles extremely sensitive and selective to hydrogen
ACS Applied Materials & Interfaces, 2016Co-Authors: F E Annanouch, Stella Vallejos, Z Haddi, Min Ling, F Di Maggio, Toni Vilic, Y Zhu, T Shujah, Polona Umek, Carla BittencourtAbstract:We report for the first time the successful synthesis of palladium (Pd) nanoparticle (NP)-decorated tungsten trioxide (WO3) nanoneedles (NNs) via a two-step aerosol-assisted chemical vapor deposition approach. Morphological, structural, and elemental composition analysis revealed that a Pd(acac)2 precursor was very suitable to decorate WO3 NNs with uniform and well-dispersed PdO NPs. Gas-sensing results revealed that decoration with PdO NPs led to an ultrasensitive and selective hydrogen (H2) gas Sensor (Sensor Response peaks at 1670 at 500 ppm of H2) with low operating temperature (150 °C). The Response of decorated NNs is 755 times higher than that of bare WO3 NNs. Additionally, at a temperature near that of the ambient temperature (50 °C), the Response of this Sensor toward the same concentration of H2 was 23, which is higher than that of some promising Sensors reported in the literature. Finally, humidity measurements showed that PdO/WO3 Sensors displayed low-cross-sensitivity toward water vapor, compared to bare WO3 Sensors. The addition of PdO NPs helps to minimize the effect of ambient humidity on the Sensor Response.
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micromachined gas Sensors based on tungsten oxide nanoneedles directly integrated via aerosol assisted cvd
Sensors and Actuators B-chemical, 2014Co-Authors: Toni Stoycheva, E Llobet, X Correig, F E Annanouch, I Gracia, Christopher S Blackman, Stella VallejosAbstract:Abstract Micromachined gas Sensors based on tungsten oxide nanostructures (NSs) in the form of polycrystalline films, non-aligned and quasi-aligned nanoneedles (NNs) films are fabricated by integrating various microsystems technology steps with aerosol assisted chemical vapour deposition (AACVD). Measurement of the performance of these structures to various analytes, including NO2, H2, EtOH, H2S, CO, C6H6, demonstrate enhanced sensing properties for gas Sensors based on films comprised of NNs as opposed to polycrystalline, with non-aligned NNs films showing the greatest Sensor Responses. A marked contribution of the NNs diameter to the Sensor Response is noticed, particularly for Sensors composed of NNs with diameters between 25 and 50 nm. In addition, fabrication variables such as the NNs arrangement and the electrode geometry suggest their contribution to the Sensor Response is connected with the effects of the gaseous analytes at the surface, i.e. whether these analytes act as reducing or oxidizing agents.
B C Yadav - One of the best experts on this subject based on the ideXlab platform.
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fabrication of self assembled hierarchical flowerlike zinc stannate thin film and its application as liquefied petroleum gas Sensor
Sensors and Actuators B-chemical, 2014Co-Authors: Satyendra Singh, Archana Singh, Meher Wan, Raja Ram Yadav, Poonam Tandon, S S A Rasool, B C YadavAbstract:Abstract In the present communication, hierarchical flowerlike zinc stannate architectures have been fabricated using sol–gel spin coating process. X-ray diffraction analysis confirms the formation of zinc stannate with minimum crystallite size ∼7 nm. The particle size distribution was determined with the help of acoustic spectroscopy using acoustic particle sizer (APS-100). Surface morphology exhibits the formation of porous hierarchical structure having a number of gas adsorption sites. Optical characterizations were recorded using UV–visible absorption spectroscopy and Fourier transforms infrared spectroscopy. Thermal properties were studied using a hot disk thermal constants analyzer (TPS-500). Further, the fabricated thin film was investigated with the exposure of liquefied petroleum gas (LPG) at room temperature (25 °C). The maximum sensitivity of the Sensor was found 2.5. The Response and recovery times were found ∼180 and 240 s, respectively. Maximum percentage Sensor Response of the Sensor was 143. Improved sensitivity and percentage Sensor Response, small Response time and good reproducibility identify that the fabricated LPG Sensor is challenging for the detection of LPG at room temperature.
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synthesis and characterization of cuo sno2 nanocomposite and its application as liquefied petroleum gas Sensor
Materials Science in Semiconductor Processing, 2014Co-Authors: Satyendra Singh, Archana Singh, B C Yadav, Nidhi VermaAbstract:Abstract Present paper reports the synthesis of CuO–SnO2 nanocomposite via sol–gel route as a sensing material for a liquefied petroleum gas (LPG). X-ray diffraction analysis confirmed the formation of CuO–SnO2 nanocomposite. Crystallite size was found 5 nm. The optical band gap of the nanocomposite was found 4.1 eV. The thin/thick films were fabricated using spin coating and screen printing technology respectively and investigated with the exposition of LPG at room temperature (25 °C). Surface morphology of the thin film exhibits that it has a number of gas adsorption sites. The sensitivities of the thick and thin film Sensors were found 4.1 and 42 respectively. The Response and recovery times of the fabricated film Sensor were 180 and 200 s respectively. Maximum Sensor Response of thin film Sensor was found 4100. Better sensitivity and percentage Sensor Response, small Response and recovery times, and good reproducibility and stability recognize the fabricated thin film of CuO–SnO2 as a challenging material for the detection of LPG.
Kengo Shimanoe - One of the best experts on this subject based on the ideXlab platform.
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effect of water vapor on pd loaded sno2 nanoparticles gas Sensor
ACS Applied Materials & Interfaces, 2015Co-Authors: Koichi Suematsu, Masayoshi Yuasa, Tetsuya Kida, Kengo ShimanoeAbstract:The effect of water vapor on Pd-loaded SnO2 Sensor was investigated through the oxygen adsorption behavior and sensing properties toward hydrogen and CO under different humidity conditions. On the basis of the theoretical model reported previously, it was found that the mainly adsorbed oxygen species on the SnO2 surface in humid atmosphere was changed by loading Pd, more specifically, for neat SnO2 was O–, while for 0.7% Pd-SnO2 was O2–. The water vapor poisoning effect on electric resistance and Sensor Response was reduced by loading Pd. Moreover the Sensor Response in wet atmosphere was greatly enhanced by loading Pd. It seems that the electron depletion layer by p–n junction of PdO-SnO2 may impede OH– adsorption.
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pore and particle size control of gas sensing films using sno2 nanoparticles synthesized by seed mediated growth design of highly sensitive gas Sensors
Journal of Physical Chemistry C, 2013Co-Authors: Tetsuya Kida, Masayoshi Yuasa, Koichi Suematsu, Shuhei Fujiyama, Kengo ShimanoeAbstract:Gas sensing is an important application of metal oxides. The gas Sensor Response of metal oxide films is greatly influenced by particle size, pore size, thickness, and surface states. To study the effects of particle and pore sizes of sensing films on sensitivity, we fabricated SnO2-based films with different particle and pore sizes and studied Sensor Responses to three different gases: H2, CO, and H2S with different Knudsen diffusion coefficients. The pore size radii of the gas sensing films were successfully controlled from 2.8 to 5.5 nm using SnO2 nanoparticles of different sizes (4–17 nm diameter) that were synthesized by seed-mediated growth under hydrothermal conditions. Sensor Response to H2 increased with decreasing particle size because of the formation of an electron depletion layer within the nanosized crystals. In contrast, the Response to CO and H2S increased with increasing particle size and the resultant pore size. Using the Knudsen diffusion-surface reaction equation, we simulated a gas co...
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microstructure control of tio2 nanotubular films for improved voc sensing
Sensors and Actuators B-chemical, 2011Co-Authors: Min Hyu Seo, Masayoshi Yuasa, Noboru Yamazoe, Tetsuya Kida, Jeung Soo Huh, Kengo ShimanoeAbstract:Abstract Porous gas sensing films composed of TiO 2 nanotubes were fabricated for the detection of volatile organic compounds (VOCs), such as alcohol and toluene. In order to control the microstructure of TiO 2 nanotubular films, ball-milling treatments were used to shorten the length of TiO 2 nanotubes and to improve the particle packing density of the films without destroying their tubular morphology and crystal structure. The ball-milling treatment successfully modified the porosity of the gas sensing films by inducing more intimate contacts between nanotubes, as confirmed by scanning electron microscopy (SEM) and mercury porosimetry. The Sensor using nanotubes after the ball-milling treatment for 3 h exhibited an improved Sensor Response and selectivity to toluene (50 ppm) at the operating temperature of 500 °C. However, an extensive ball-milling treatment did not enhance the original Sensor Response, probably owing to a decrease in the porosity of the film. The results obtained indicated the importance of the microstructure control of sensing layers in terms of particle packing density and porosity for detecting large sized organic gas molecules.
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nano sized pdo loaded sno2 nanoparticles by reverse micelle method for highly sensitive co gas Sensor
Sensors and Actuators B-chemical, 2009Co-Authors: Masayoshi Yuasa, Kengo Shimanoe, Takanori Masaki, Tetsuya Kida, Noboru YamazoeAbstract:Abstract A reverse micelle method was investigated for preparing nano-sized PdO loaded on SnO 2 nanoparticles. PdO–SnO 2 nano-composite was prepared by precipitating Pd(OH) 2 and Sn(OH) 4 inside a reverse micelle. The microstructure and the gas sensing properties of obtained nanoparticles were investigated. Although the particle size of SnO 2 was as same as ca. 10 nm at each observed sample, the particle size of PdO got larger as increasing with loading amount of PdO because of agglomeration of PdO nanoparticles each other. As a result of the gas sensing measurement, it was found that the particle size of PdO on SnO 2 nanoparticle influences the gas sensing property closely. That is, the Sensor Response declined gradually with increasing the particle size of PdO although the maximum of the Sensor Response was obtained in PdO = 0.1 mol%. In this method, small amount of PdO loading can be achieved as compared with PdO-loaded SnO 2 Sensor prepared by the conventional impregnation method.
Sunil K Khijwania - One of the best experts on this subject based on the ideXlab platform.
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effective refractive index modulation based optical fiber humidity Sensor employing etched fiber bragg grating
International Conference on Optical Fibre Sensors (OFS24), 2015Co-Authors: Pathi Mundendhar, Sunil K KhijwaniaAbstract:Relative humidity (RH) Sensor employing etched fiber Bragg grating (FBG) is reported where RH variations are captured using effective-index-modulation, rather than traditional strain-modulation. Additionly, linear Sensor Response over wide dynamic range with optimum characteristics is focused. Comprehensive experimental investigation is carried out for the Sensor that comprises uniformly etched cladding in the FBG region. Obtained results are observed to be in agreement with the theoretical analysis. Sensor Response is observed to be linear over dynamic range 3–94%RH with ~ 0.082 pm/%RH sensitivity, ~0.6%RH resolution, ~ ±2.5%RH accuracy, ~ ±0.2 pm average discrepancy and ~ 0.2s Response time during humidification/desiccation.
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zinc oxide nanoparticle doped nanoporous solgel fiber as a humidity Sensor with enhanced sensitivity and large linear dynamic range
Applied Optics, 2013Co-Authors: R Aneesh, Sunil K KhijwaniaAbstract:An all-optical humidity Sensor based on direct and exhaustive guided-mode attenuation in an in-house developed zinc oxide (ZnO) nanoparticle-immobilized bare solgel fiber is reported. The main objective of the present work is to enhance the sensitivity considerably while realizing a throughout linear Response over a wide dynamic range. The developed Sensor is characterized and performance characteristics of the Sensor are compared with an optical fiber humidity Sensor employing an evanescent wave absorption scheme in a straight and uniform probe, with ZnO nanoparticles-immobilized solgel film as humidity sensing cladding. Sensor Response is observed to be linear over a wide dynamic range of 5%–95% relative humidity (RH). The observed linear sensitivity is 0.0103/% RH, which is ∼9 times higher than the Sensor employing the evanescent wave absorption scheme. In addition, Sensor Response is observed to be very fast, highly reversible, and repeatable.
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titanium dioxide nanoparticle based optical fiber humidity Sensor with linear Response and enhanced sensitivity
Applied Optics, 2012Co-Authors: R Aneesh, Sunil K KhijwaniaAbstract:An optical fiber humidity Sensor employing an in-house scaled TiO2-nanoparticle doped nanostructured thin film as the fiber sensing cladding and evanescent wave absorption is reported. The main objective of the present work is to achieve a throughout-linear Sensor Response with high sensitivity, possibly over a wide dynamic range using the simplest possible Sensor geometry. In order to realize this, first, the nanostructured sensing film is synthesized over a short length of a centrally decladded straight and uniform optical fiber and then a comprehensive experimental investigation is carried out to optimize the design configuration/parameters of the nanostructured sensing film and to achieve the best possible Sensor Response. Much improved sensitivity of 27.1 mV/%RH is observed for the optimized Sensor along with a throughout-linear Sensor Response over a dynamic range as wide as 24% to 95%RH with an average Response time of 0.01 s for humidification and 0.06 s for desiccation. In addition, the Sensor exhibits a very good degree of reversibility and repeatability.
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zinc oxide nanoparticle based optical fiber humidity Sensor having linear Response throughout a large dynamic range
Applied Optics, 2011Co-Authors: R Aneesh, Sunil K KhijwaniaAbstract:The main objective of the present work is to develop an optical fiber relative humidity (RH) Sensor having a linear Response throughout over the widest possible dynamic range. We report an optical fiber RH Sensor based on the evanescent wave absorption spectroscopy that fulfills this objective. The fiber Sensor employs a specific nanoparticle (zinc oxide) doped sol–gel nanostructured sensing film of optimum thickness, synthesized over a short length of a centrally decladded straight and uniform optical fiber. A detailed experimental investigation is carried out to analyze the Sensor Response/characteristics. Fiber Sensor Response is observed to be linear throughout the dynamic range as wide as 4% to 96% RH. The observed linear sensitivity for the fiber Sensor is 0.0012 RH−1. The average Response time of the reported Sensor is observed to be as short as 0.06 s during the humidification. In addition, the Sensor exhibited a very good degree of reversibility and extremely high reliability as well as repeatability.
Tetsuya Kida - One of the best experts on this subject based on the ideXlab platform.
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effect of water vapor on pd loaded sno2 nanoparticles gas Sensor
ACS Applied Materials & Interfaces, 2015Co-Authors: Koichi Suematsu, Masayoshi Yuasa, Tetsuya Kida, Kengo ShimanoeAbstract:The effect of water vapor on Pd-loaded SnO2 Sensor was investigated through the oxygen adsorption behavior and sensing properties toward hydrogen and CO under different humidity conditions. On the basis of the theoretical model reported previously, it was found that the mainly adsorbed oxygen species on the SnO2 surface in humid atmosphere was changed by loading Pd, more specifically, for neat SnO2 was O–, while for 0.7% Pd-SnO2 was O2–. The water vapor poisoning effect on electric resistance and Sensor Response was reduced by loading Pd. Moreover the Sensor Response in wet atmosphere was greatly enhanced by loading Pd. It seems that the electron depletion layer by p–n junction of PdO-SnO2 may impede OH– adsorption.
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pore and particle size control of gas sensing films using sno2 nanoparticles synthesized by seed mediated growth design of highly sensitive gas Sensors
Journal of Physical Chemistry C, 2013Co-Authors: Tetsuya Kida, Masayoshi Yuasa, Koichi Suematsu, Shuhei Fujiyama, Kengo ShimanoeAbstract:Gas sensing is an important application of metal oxides. The gas Sensor Response of metal oxide films is greatly influenced by particle size, pore size, thickness, and surface states. To study the effects of particle and pore sizes of sensing films on sensitivity, we fabricated SnO2-based films with different particle and pore sizes and studied Sensor Responses to three different gases: H2, CO, and H2S with different Knudsen diffusion coefficients. The pore size radii of the gas sensing films were successfully controlled from 2.8 to 5.5 nm using SnO2 nanoparticles of different sizes (4–17 nm diameter) that were synthesized by seed-mediated growth under hydrothermal conditions. Sensor Response to H2 increased with decreasing particle size because of the formation of an electron depletion layer within the nanosized crystals. In contrast, the Response to CO and H2S increased with increasing particle size and the resultant pore size. Using the Knudsen diffusion-surface reaction equation, we simulated a gas co...
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microstructure control of tio2 nanotubular films for improved voc sensing
Sensors and Actuators B-chemical, 2011Co-Authors: Min Hyu Seo, Masayoshi Yuasa, Noboru Yamazoe, Tetsuya Kida, Jeung Soo Huh, Kengo ShimanoeAbstract:Abstract Porous gas sensing films composed of TiO 2 nanotubes were fabricated for the detection of volatile organic compounds (VOCs), such as alcohol and toluene. In order to control the microstructure of TiO 2 nanotubular films, ball-milling treatments were used to shorten the length of TiO 2 nanotubes and to improve the particle packing density of the films without destroying their tubular morphology and crystal structure. The ball-milling treatment successfully modified the porosity of the gas sensing films by inducing more intimate contacts between nanotubes, as confirmed by scanning electron microscopy (SEM) and mercury porosimetry. The Sensor using nanotubes after the ball-milling treatment for 3 h exhibited an improved Sensor Response and selectivity to toluene (50 ppm) at the operating temperature of 500 °C. However, an extensive ball-milling treatment did not enhance the original Sensor Response, probably owing to a decrease in the porosity of the film. The results obtained indicated the importance of the microstructure control of sensing layers in terms of particle packing density and porosity for detecting large sized organic gas molecules.
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nano sized pdo loaded sno2 nanoparticles by reverse micelle method for highly sensitive co gas Sensor
Sensors and Actuators B-chemical, 2009Co-Authors: Masayoshi Yuasa, Kengo Shimanoe, Takanori Masaki, Tetsuya Kida, Noboru YamazoeAbstract:Abstract A reverse micelle method was investigated for preparing nano-sized PdO loaded on SnO 2 nanoparticles. PdO–SnO 2 nano-composite was prepared by precipitating Pd(OH) 2 and Sn(OH) 4 inside a reverse micelle. The microstructure and the gas sensing properties of obtained nanoparticles were investigated. Although the particle size of SnO 2 was as same as ca. 10 nm at each observed sample, the particle size of PdO got larger as increasing with loading amount of PdO because of agglomeration of PdO nanoparticles each other. As a result of the gas sensing measurement, it was found that the particle size of PdO on SnO 2 nanoparticle influences the gas sensing property closely. That is, the Sensor Response declined gradually with increasing the particle size of PdO although the maximum of the Sensor Response was obtained in PdO = 0.1 mol%. In this method, small amount of PdO loading can be achieved as compared with PdO-loaded SnO 2 Sensor prepared by the conventional impregnation method.
