共查询到20条相似文献,搜索用时 31 毫秒
1.
Divya HaridasAuthor Vitae Arijit ChowdhuriAuthor VitaeK. SreenivasAuthor Vitae Vinay GuptaAuthor Vitae 《Sensors and actuators. B, Chemical》2011,153(1):152-157
The room temperature response characteristics of SnO2 thin film sensor loaded with platinum catalyst clusters are investigated for LPG under the exposure of ultraviolet radiation. The SnO2-Pt cluster sensor structures have been prepared using rf sputtering. Combined effect of UV radiation exposure (λ = 365 nm) and presence of Pt catalyst clusters (10 nm thick) on SnO2 thin film sensor surface is seen to lead to an enhanced response (4.4 × 103) for the detection of LPG (200 ppm) at room temperature whereas in the absence of UV illumination a comparable response (∼5 × 103) could be obtained but only at an elevated temperature of 220 °C. The present study therefore investigates the effect of UV illumination on LPG sensing characteristics of SnO2 sensors loaded with Pt clusters of varying thickness values. Results indicate the possibility of utilizing the sensor structure with novel dispersal of Pt catalyst clusters on SnO2 film surface for efficient detection of LPG at room temperature under the illumination of UV radiations. 相似文献
2.
Shang-Wei TsaiAuthor VitaeJin-Chern ChiouAuthor Vitae 《Sensors and actuators. B, Chemical》2011,152(2):176-182
In situ SiO2-doped SnO2 thin films were successfully prepared by liquid phase deposition. The influence of SiO2 additive as an inhibitor on the surface morphology and the grain size for the thin film has been investigated. These results show that the morphology of SnO2 film changes significantly by increasing the concentration of H2SiF6 solution which decreases the grain size of SnO2. The stoichiometric analysis of Si content in the SnO2 film prepared from various Si/Sn molar ratios has also been estimated. For the sensing performance of H2S gas, the SiO2-doped Cu-Au-SnO2 sensor presents better sensitivity to H2S gas compared with Cu-Au-SnO2 sensor due to the fact that the distribution of SiO2 particles in grain boundaries of nano-crystallines SnO2 inhibited the grain growth (<6 nm) and formed a porous film. By increasing the Si/Sn molar ratio, the SiO2-doped Cu-Au-SnO2 gas sensors (Si/Sn = 0.5) exhibit a good sensitivity (S = 67), a short response time (t90% < 3 s) and a good gas concentration characteristic (α = 0.6074). Consequently, the improvement of the nano-crystalline structures and high sensitivity for sensing films can be achieved by introducing SiO2 additive into the SnO2 film prepared by LPD method. 相似文献
3.
Divya HaridasAuthor VitaeArijit ChowdhuriAuthor Vitae K. SreenivasAuthor VitaeVinay GuptaAuthor Vitae 《Sensors and actuators. B, Chemical》2011,153(1):89-95
This paper reports the sensing response characteristics of rf-sputtered SnO2 thin films (90 nm thick) loaded with platinum catalyst cluster of varying thickness (2-20 nm) for LPG detection. The enhanced response (5 × 103) was obtained for 200 ppm LPG with the presence of 10 nm thin and uniformly distributed Pt catalyst clusters on the surface of SnO2 thin film at a relatively low operating temperature (220 °C). The high response for LPG is shown to be primarily due to the enhanced catalytic activity for adsorbed oxygen on the surface of SnO2 thin film besides the spill over mechanism at elevated temperature. 相似文献
4.
N.M. ShaalanAuthor Vitae T. YamazakiAuthor Vitae T. KikutaAuthor Vitae 《Sensors and actuators. B, Chemical》2011,153(1):11-16
SnO2 microwires, nanowires and rice-shaped nanoparticles were synthesized by a thermal evaporation method. The diameters of microwire and nanowire were 2 μm and 50-100 nm, respectively, with approximately the same length (∼20 μm). The size of nanoparticles was about 100 nm. It was confirmed that the as-synthesized products have SnO2 crystalline rutile structure. The sensing ability of SnO2 particle and wire-like structure configured as gas sensors was measured. A comparison between the particle and wire-like structure sensors revealed that the latter have numerous advantages in terms of reliability and high sensitivity. Although its high surface-to-volume ratio, the nanoparticle sensor exhibited the lowest sensitivity. The high surface-to-volume ratio and low density of grain boundaries is the best way to improve the sensitivity of SnO2 gas sensors, as in case of nanowire sensor which exhibited a dramatic improvement in sensitivity to NO2 gas. 相似文献
5.
In-Sung HwangAuthor VitaeEui-Bok LeeAuthor Vitae Sun-Jung KimAuthor VitaeJoong-Ki ChoiAuthor Vitae Jung-Ho ChaAuthor VitaeHo-Jun LeeAuthor Vitae Byeong-Kwon JuAuthor VitaeJong-Heun LeeAuthor Vitae 《Sensors and actuators. B, Chemical》2011,154(2):295-300
The SnO2 nanowires (NWs) network gas sensors were fabricated on a micro-electrode and heater suspended in a cavity. The sensors showed selective detection to C2H5OH at a heater power during sensor operation as low as 30-40 mW. The gas response and response speed of the SnO2 NWs sensor to 100 ppm C2H5OH were 4.6- and 4.7-fold greater, respectively, than those of the SnO2 nanoparticles (NPs) sensor with the same electrode geometry. The reasons for these enhanced gas sensing characteristics are discussed in relation to the sensing materials and sensor structures. 相似文献
6.
Chander ShekharAuthor VitaeK.I. GnanasekarAuthor Vitae E. PrabhuAuthor VitaeV. JayaramanAuthor Vitae T. GnanasekaranAuthor Vitae 《Sensors and actuators. B, Chemical》2011,155(1):19-27
Indium oxide (In2O3) doped with 0.5-5 at.% of Ba was examined for their response towards trace levels of NOx in the ambient. Crystallographic phase studies, electrical conductivity and sensor studies for NOx with cross interference for hydrogen, petroleum gas (PG) and ammonia were carried out. Bulk compositions with x ≤ 1 at.% of Ba exhibited high response towards NOx with extremely low cross interference for hydrogen, PG and ammonia, offering high selectivity. Thin films of 0.5 at.% Ba doped In2O3 were deposited using pulsed laser deposition technique using an excimer laser (KrF) operating at a wavelength of (λ) 248 nm with a fluence of ∼3 J/cm2 and pulsed at 10 Hz. Thin film sensors exhibited better response towards 3 ppm NOx quite reliably and reproducibly and offer the potential to develop NOx sensors (Threshold limit value of NO2 and NO is 3 and 25 ppm, respectively). 相似文献
7.
Lili WangAuthor VitaeZheng LouAuthor Vitae Tong ZhangAuthor Vitae Huitao FanAuthor VitaeXiujuan XuAuthor Vitae 《Sensors and actuators. B, Chemical》2011,155(1):285-289
Hierarchical SnO2 microspheres were synthesized by a hydrothermal method at 140 °C using stannic chloride hydrate and sodium hydroxide as starting materials. The individual hierarchical SnO2 microsphere ranged from 700 to 900 nm in diameter. After these microspheres were heated at 600 °C for 2 h, the spheres were cross-linked into clusters by short SnO2 nanorods as revealed by X-ray powder diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). Most importantly, SnO2 hierarchical microsphere sensor exhibits excellent selectivity and fast response to ethanol. Response and recovery times were 0.6 s and 11 s when the sensor was exposed to 50 ppm ethanol at an operating temperature of 300 °C. Thus, hierarchical structures play a significant role in the field of gas sensing. 相似文献
8.
Sun-Jung KimAuthor VitaeIn-Sung HwangAuthor Vitae Joong-Ki ChoiAuthor VitaeYun Chan KangAuthor Vitae Jong-Heun LeeAuthor Vitae 《Sensors and actuators. B, Chemical》2011,155(2):512-518
In2O3 hollow spheres with shell thicknesses of ∼150 nm and ∼300 nm were prepared by the one-pot synthesis of indium-precursor-coated carbon spheres via hydrothermal reaction and subsequent removal of core carbon by heat treatment. The gas response (Ra/Rg, Ra: resistance in air, Rg: resistance in gas) of the thin hollow spheres to 100 ppm C2H5OH was 137.2 at 400 °C, which was 1.86 and 3.84 times higher than that of the thick hollow spheres and of the nanopowders prepared by precipitation, respectively. The gas sensing characteristics are discussed in relation to the shell configuration of the hollow spheres. The enhanced gas response of the hollow spheres was attributed to the effective diffusion of analyte gas toward the entire sensor surface via very thin and nano-porous shells. 相似文献
9.
Salim F. BamsaoudAuthor Vitae S.B. RaneAuthor Vitae R.N. KarekarAuthor VitaeR.C. AiyerAuthor Vitae 《Sensors and actuators. B, Chemical》2011,153(2):382-391
SnCl2 (solution) was spin coated on soda lime glass and Al2O3 substrate to obtain nano-particulate tin oxide film, directly by sintering at 550 °C for 40 minutes (min). The surface morphology and crystal structure of the tin oxide films were analyzed using atomic force microscopy (AFM) and X-ray diffraction (XRD). The size of SnO2 nanostructure was determined from UV-vis and found to be ?3 nm. These films were tested for sensing H2 concentration of 0.1-1000 ppm at optimized operating temperature of 265 °C. The results showed that sensitivity (Rair/Rgas per ppm) goes on increasing with decreasing concentration of test gas, giving concentration dependent changes. Special studies carried out at low concentration levels (0.1-1 and 1-10 ppm) of H2, give high sensitivity (200 × 10−3/ppm) for lowest concentration (0.1-1 ppm) of H2. The selectivity for H2 against relative humidity (RH), CO2, CO and LPG gases is also good. The sensor, at operating temperature of 200 °C, is showing nearly zero response to 300 ppm of H2, and offering response to acetone vapour of 11 ppm. Selectivity for acetone against RH% and CO2 was also studied. These sensors can be used as H2 sensor at an operating temperature of 265 °C, and as an acetone sensor at the operating temperature of 200 °C. 相似文献
10.
Viruntachar KruefuAuthor VitaeChaikarn LiewhiranAuthor Vitae Anurat WisitsoraatAuthor VitaeSukon PhanichphantAuthor Vitae 《Sensors and actuators. B, Chemical》2011,156(1):360-367
Unloaded ZnO and Nb/ZnO nanoparticles containing 0.25, 0.5 and 1 mol.% Nb were produced in a single step by flame-spray pyrolysis (FSP) technique. The nanoparticles were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The BET surface area (SSABET) of the nanoparticles was measured by nitrogen adsorption. FSP yielded small Nb particles attached to the surface of the supporting ZnO nanoparticles, indicating a high SSABET. The morphology and accurate size of the primary particles were further investigated by TEM. Nb/ZnO nanoparticles paste composed of ethyl cellulose and terpineol as binder and solvent respectively was coated on Al2O3 substrate interdigitated with gold electrodes to form thick films by spin coating technique. After the sensing tests, the morphology and the cross-section of sensing film were analyzed by SEM and EDS analyses. The influence on a low dynamic range of Nb concentration on NO2 response (0.1-4 ppm) of thick film sensor elements was studied at the operating temperatures ranging from 250 to 350 °C in the presence of dry air. The optimum Nb concentration was found be 0.5 mol.% and 0.5 mol.% Nb exhibited an optimum NO2 response of ∼1640 and a short response time (27 s) for NO2 concentration of 4 ppm at 300 °C. 相似文献
11.
Ki-Young DongAuthor VitaeJoong-Ki ChoiAuthor Vitae In-Sung HwangAuthor VitaeJin-Woo LeeAuthor Vitae Byung Hyun KangAuthor VitaeDae-Jin HamAuthor Vitae Jong-Heun LeeAuthor VitaeByeong-Kwon JuAuthor Vitae 《Sensors and actuators. B, Chemical》2011,157(1):154-161
Gas sensors were designed and fabricated using oxide nanofibers as the sensing materials on micro platforms using micromachining technology. Pure and Pt doped SnO2 nanofibers were prepared by electrospinning and their H2S gas sensing characteristics were subsequently investigated. The sensing temperatures of 300 and 500 °C could be attained at the heater powers of 36 and 94 mW, respectively, and the sensors showed high and fast responses to H2S. The responses of 0.08 wt% Pt doped SnO2 nanofibers to 4-20 ppm H2S, were 25.9-40.6 times higher than those of pure SnO2 nanofibers. The gas sensing characteristics were discussed in relation to the catalytic promotion effect of Pt, nano-scale morphology of electrospun nanofibers, and sensor platform using micro heater. 相似文献
12.
Chunbae LimAuthor VitaeWen WangAuthor Vitae Sangsik YangAuthor VitaeKeekeun LeeAuthor Vitae 《Sensors and actuators. B, Chemical》2011,154(1):9-16
A 440 MHz wireless and passive surface acoustic wave (SAW)-based multi-gas sensor integrated with a temperature sensor was developed on a 41° YX LiNbO3 piezoelectric substrate for the simultaneous detection of CO2, NO2, and temperature. The developed sensor was composed of a SAW reflective delay lines structured by an interdigital transducer (IDT), ten reflectors, a CO2 sensitive film (Teflon AF 2400), and a NO2 sensitive film (indium tin oxide). Teflon AF 2400 was used for the CO2 sensitive film because it provides a high CO2 solubility, with good permeability and selectivity. For the NO2 sensitive film, indium tin oxide (ITO) was used. Coupling of mode (COM) modeling was conducted to determine the optimal device parameters prior to fabrication. Using the parameters determined by the simulation results, the device was fabricated and then wirelessly measured using a network analyzer. The measured reflective coefficient S11 in the time domain showed high signal/noise (S/N) ratio, small signal attenuation, and few spurious peaks. The time positions of the reflection peaks were well matched with the predicted values from the simulation. High sensitivity and selectivity were observed at each target gas testing. The obtained sensitivity was 2.12°/ppm for CO2 and 51.5°/ppm for NO2, respectively. With the integrated temperature sensor, temperature compensation was also performed during gas sensitivity evaluation process. 相似文献
13.
Eric R. MacamAuthor VitaeBryan M. BlackburnAuthor Vitae Eric D. WachsmanAuthor Vitae 《Sensors and actuators. B, Chemical》2011,158(1):304-312
The intent of this work is to look at the effects of varying the La2CuO4 electrode area and the asymmetry between the sensing and counter electrode in a solid state potentiometric sensor with respect to NOx sensitivity. NO2 sensitivity was observed at 500-600 °C with a maximum sensitivity of ∼22 mV/decade [NO2] observed at 500 °C for the sensor with a La2CuO4 electrode area of ∼30 mm2. The relationship between NO2 sensitivity and area is nearly parabolic at 500 °C, decreases linearly with increasing electrode area at 600 °C, and was a mixture of parabolic and linear behavior 550 °C. NO sensitivity varied non-linearly with electrode area with a minima (maximum sensitivity) of ∼−22 mV/decade [NO] at 450 °C for the sensor with a La2CuO4 electrode area of 16 mm2. The behavior at 400 °C was similar to that of 450 °C, but with smaller sensitivities due to a saturation effect. At 500 °C, NO sensitivity decreases linearly with area.We also used electrochemical impedance spectroscopy (EIS) to investigate the electrochemical processes that are affected when the sensing electrode area is changed. Changes in impedance with exposure to NOx were attributed to either changes in La2CuO4 conductivity due to gas adsorption (high frequency impedance) or electrocatalysis occurring at the electrode/electrolyte interface (total electrode impedance). NO2 caused a decrease in high frequency impedance while NO caused an increase. In contrast, NO2 and NO both caused a decrease in the total electrode impedance. The effect of area on both the potentiometric and impedance responses show relationships that can be explained through the mechanistic contributions included in differential electrode equilibria. 相似文献
14.
Hiroyuki YamauraAuthor VitaeYuji IwasakiAuthor Vitae Shinsuke HiraoAuthor VitaeHidenori YahiroAuthor Vitae 《Sensors and actuators. B, Chemical》2011,153(2):465-467
The CO sensing property of CuO-loaded SnO2-In2O3 sensor was investigated in a reducing atmosphere. The sensor response to CO for CuO/SnO2-In2O3 (8/2) was much higher than that for CuO/SnO2 in the range of 200-1000 ppm of CO concentration. Such a high sensor response of CuO/SnO2-In2O3 may originate from the high dispersion of CuO playing a role as sensing site. 相似文献
15.
Chia-Yu LinAuthor VitaeJiang-Ging ChenAuthor Vitae Wei-Yi FengAuthor VitaeChii-Wann LinAuthor Vitae Ju-Wen HuangAuthor VitaeJames J. TunneyAuthor Vitae Kuo-Chuan HoAuthor Vitae 《Sensors and actuators. B, Chemical》2011,157(2):361-367
NO gas sensors, based on ZnO thin film (ZnOfilm), TiO2 nanoparticulate film (TiO2NP), and TiO2NP/ZnOfilm double-layer film, were fabricated, and their sensing characteristics towards NO gas were investigated in this study. The maximal response of a ZnOfilm deposited onto a rougher Al2O3 substrate, towards NO gas, was higher than that of a ZnOfilm deposited on a smoother glass substrate. Although the sensing response of the TiO2NPs itself towards NO gas was minute, the TiO2NP/ZnOfilm double-layer film showed enhanced response as compared with TiO2NP or ZnOfilm single-layer film. In addition, the sensor response of the TiO2NP/ZnOfilm double-layer film was strongly influenced by the annealing time for the film preparation; the maximum response to NO was enhanced about 6.2 times as the annealing time was increased from 30 min to 2 h. Based on the XPS results, the increase in the transition zone between TiO2NP and ZnOfilm along with the appearance of Ti3+ state was noticed when the annealing time was increased. With the high sensitive TiO2NP/ZnOfilm/Al2O3 electrode, the limit of detection (S/N = 3) can be achieved at 8.8 ppb. The double-layer TiO2NP/ZnOfilm also showed improved selectivities with respect to NO2 and CO. 相似文献
16.
Detection of low concentrations of petroleum gas was achieved using transparent conducting SnO2 thin films doped with 0–4 wt.% caesium (Cs), deposited by spray pyrolysis technique. The electrical resistance change of the films was evaluated in the presence of LPG upon doping with different concentrations of Cs at different working temperatures in the range 250–400 °C. The investigations showed that the tin oxide thin film doped with 2% Cs with a mean grain size of 18 nm at a deposition temperature of 325 °C showed the maximum sensor response (93.4%). At a deposition temperature of 285 °C, the film doped with 3% Cs with a mean grain size of 20 nm showed a high response of 90.0% consistently. The structural properties of Cs-doped SnO2 were studied by means of X-ray diffraction (XRD); the preferential orientation of the thin films was found to be along the (3 0 1) directions. The crystallite sizes of the films determined from XRD are found to vary between 15 and 60 nm. The electrical investigations revealed that Cs-doped SnO2 thin film conductivity in a petroleum gas ambience and subsequently the sensor response depended on the dopant concentration and the deposition temperature of the film. The sensors showed a rapid response at an operating temperature of 345 °C. The long-term stability of the sensors is also reported. 相似文献
17.
Jin Hyung Junggwon Kyoungah In-Sung Jong-Heun Sangsig 《Sensors and actuators. B, Chemical》2009,140(2):412-417
The NO2 gas sensing characteristics of semiconductor type gas sensors with channels composed of necked ZnO nanoparticles (NPs) were investigated in this study. The heat treatment of the NPs at 400 °C led to their necking and coarsening. The response of the necked-NP-based sensors was as high as 100 when exposed to 0.2 ppm of NO2 at 200 °C. As the concentration of NO2 increased to 5 ppm, their response was enhanced to approximately 400. During the repeated injection of NO2 gas with a concentration of 0.4 ppm, the sensors exhibited stable response characteristics. Furthermore, the 90% response and recovery times of the gas sensor were as fast as 13 and 10 s, respectively. These observations indicate that the non-agglomerated necking of the NPs induced by the heat treatment significantly enhances the gas sensing characteristics of the NP-based gas sensors. 相似文献
18.
Pure and Sm2O3-doped SnO2 are prepared through a sol–gel method and characterized by X-ray diffraction (XRD) and transmission electron microscopy (TEM). The sensor based on 6 wt% Sm2O3-doped SnO2 displays superior response at an operating temperature of 180 °C, and the response magnitude to 1000 ppm C2H2 can reach 63.8, which is 16.8 times larger than that of pure SnO2. This sensor also shows high sensitivity under various humidity conditions. These results make our product be a good candidate in fabricating C2H2 sensors. 相似文献
19.
This paper presents the ability of electrostatic sprayed tin oxide (SnO2) and tin oxide doped with copper oxide (1, 2, and 4 at.% Cu) films to detect different pollutant gases, i.e., H2S, SO2, and NO2. The influence of a copper oxide dopant on the SnO2 morphology is studied using scanning electron microscopy (SEM) technique, which reveals a small decrease in the porosity and particle size when the amount of dopant is increased. The sensing properties of the SnO2 films are greatly improved by doping, i.e., the Cu-doped SnO2 films have large response to low concentration (10 ppm) of H2S at low operating temperature (100 °C). Furthermore, no cross-sensitivity to 1 ppm NO2 and 20 ppm SO2 is observed. Among the studied films, the 1 at.% Cu-doped SnO2 layer is the most sensitive in the detection of all the studied gases. 相似文献
20.
In-Sung Joong-Ki Sun-Jung Ki-Young Jae-Hong Byeong-Kwon Jong-Heun 《Sensors and actuators. B, Chemical》2009,142(1):105-110
The CuO-functionalized SnO2 nanowire (NW) sensors were fabricated by depositing a slurry containing SnO2 NWs on a polydimethylsiloxane (PDMS)-guided substrate and subsequently dropping Cu nitrate aqueous solution. The CuO coating increased the gas responses to 20 ppm H2S up to 74-fold. The Ra/Rg value of the CuO-doped SnO2 NWs to 20 ppm H2S was as high as 809 at 300 °C, while the cross-gas responses to 5 ppm NO2, 100 ppm CO, 200 ppm C2H5OH, and 100 ppm C3H8 were negligibly low (1.5–4.0). Moreover, the 90% response times to H2S were as short as 1–2 s at 300–400 °C. The selective detection of H2S and enhancement of the gas response were attributed to the uniform distribution of the sensitizer (CuO) on the surface of the less agglomerated network of the SnO2 NWs. 相似文献