• 센서학회지
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• 제16권1호
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• pp.7-10
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• 2007

A thick film catalytic gas sensors which can be operated at $142^{\circ}C$ in presence of ultra violet-light emitting diode has been developed to measure hydrogen concentration in 0-5 % range. The sensing material as a combustion catalyst consists of $TiO_{2}$ (5 wt%) and Pd/Pt (20 wt%) supported on $Al_{2}O_{3}$ powder and the reference material to compensate the heat capacity of it in a bridge circuit was an catalyst free $Al_{2}O_{3}$ powder. Platinum heater and sensor materials were formed on the alumina plate by screen printing method and heat treatment. The effect of UV radiation in the presence of photo catalyst $TiO_{2}$ on the sensor sensitivity, response and recovery time has been investigated. The reduction of operating temperature from $192^{\circ}C$ to $142^{\circ}C$ for hydrogen gas sensing property in presence of UV radiation is attributed to the hydroxy radical and superoxide which was formed at the surface of $TiO_{2}$ under UV radiation.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 1998년도 추계종합학술대회 논문집
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• pp.601-604
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• 1998

NOX detecting gas sensors using TiO2 doped tungsten oxide semiconductor were prepared and their electrical and sensing characteristics have been investigated. In normal air condition, the sensors of WO3, TiO2 doped WO3 show grain boundary heights of 0.34 eV, 0.25 eV, respectively. The grain boundary barrier energy variation was increased by doping TiO2 into large variation of resistance to NOX gases. And doping the TiO2 4 wt.%, the particle size of WO3 polycrystal films showed higher sensitivity and better sorption characteristics to NOX gas than the pure WO3 films material in air at operating temperature of $350^{\circ}C.$ The TiO2 doped WO3 semiconductor gas sensor shows nano-sized particle size and good sensitivity to sub-ppm concentration of NOX.

• 센서학회지
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• 제23권5호
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• pp.305-309
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• 2014

Well-ordered $TiO_2$ nanotubes with Au nanoparticles are a desirable configuration to enhance the gas sensing properties such as response and selectivity due to their high surface area to volume ratio and catalytic effect of Au nanoparticles. We have synthesized the well-ordered $TiO_2$ nanotubes directly on a Pt IDEs patterned $SiO_2/Si$ substrate and then decorated Au nanoparticles on inner and outer surface of $TiO_2$ nanotubes using electrodeposition method. The Au-decorated $TiO_2$ nanotubes shows ultrahigh response to $C2_H_5OH$ and the highest increasing ratio to $H_2$ compared with other gases.

• 센서학회지
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• 제18권3호
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• pp.217-221
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• 2009

Different methods of material engineering, used for improvement of solid state gas sensors parameters are reviewed in this report. The wide possibilities of material engineering in optimization of gas sensing properties were demonstrated on the example of $SnO_2,\;TiO_2\;and\;In_2O_3$-based sensors.

• 센서학회지
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• 제18권6호
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• pp.456-461
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• 2009

Perovskite-structure $Sr(Ti_{1-x}Fe_x)O_3$ thick films, in which x is 0.4 or 0.6, were prepared by normal ceramic process on alumina substrate. Electrical resistance was measured as a function of thermal treatment condition including atmosphere, time, and temperature. The resistance of $Sr(Ti_{1-x}Fe_x)O_3$ films is lower than those of $SrTiO_3$ or $SrFeO_3$ films. The temperature coefficient of resistance over $550^{\circ}C$ was measured to be 0 for the $Sr(Ti_{1-x}Fe_x)O_3$ films after thermal treatment at $1100^{\circ}C$ in air. The sensing property of the films was also measured as a function of temperature and gas such as $O_2$, CO, $CO_2$, NO and $NO_2$. $Sr(Ti_{1-x}Fe_x)O_3$ films showed a good sensing property for $O_2$, but no sensing signal for CO, $CO_2$, NO and $NO_2$.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 1997년도 춘계학술대회 논문집
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• pp.99-102
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• 1997

An electronic nose system is an instrument designed far mimicking human olfactory system. It consists generally of gas (odor) sensor array corresponding to olfactory receptors of human nose and artificial neural network pattern recognition technique based on human biological odor sensing mechanism. Considerable attempts to develop the electronic nose system have been made far applications in the fields of floods, drinks, cosmetics, environment monitoring, etc. A portable electronic nose system has been fabricated by using oxide semiconductor gas sensor array and pattern recognition technique such as principal component analysis (PCA) and back propagation artificial neural network The sensor array consists of six thick film gas sensors whose sensing layers are Pd-doped WO$_3$ Pt-doped SnO$_2$ TiO$_2$-Sb$_2$O$_3$-Pd-doped SnO$_2$ TiO$_2$-Sb$_2$O$_{5}$-Pd-doped SnO$_2$+Pd filter layer, A1$_2$O$_3$-doped ZnO and PdCl$_2$-doped SnO$_2$. As an application the system has been used to identify CO/HC car exhausting gases and the identification has been successfully demonstrated.d.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2010년도 춘계학술대회 논문집
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• pp.549-550
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• 2010

• 센서학회지
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• 제20권5호
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• pp.305-310
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• 2011

This study focuses on the fabrication of $TiO_2$ nanosheets and their gas sensor application. A simple sonochemical method is employed to fabricate the $TiO_2$ nanosheets. The obtained samples were investigated by transmission electron microscope(TEM) and X-ray Diffraction(XRD). The $TiO_2$ nanosheets were coated on substrates by a dropping method followed by heat treatment. The sensor responses to volatile organic compounds(VOCs) such as toluene, benzene, ethanol and acetaldehyde were studied. It was found that the $TiO_2$ nanosheets sensors are able to detect ppb-levels of VOC gases.

• 한국재료학회:학술대회논문집
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• 한국재료학회 2011년도 춘계학술발표대회
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• pp.16.1-16.1
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• 2011

$TiO_2$ is a promising material for gas sensors. To achieve high sensitivities, the material should exhibit a large surface-to-volume ratio and possess the high accessibility of the gas molecules to the surface. Accordingly, a wide variety of porous $TiO_2$ nanomaterials synthesized by wet-chemical methods have been reported for gas sensor applications. Nonetheless, achieving the large-area uniformity and comparability with well-established semiconductor production processes of the methods is still challenging. An alternative method is soft-templating which utilizes nanostructured inorganic or organic materials as sacrificial templates for the preparation of porous materials. Fabrication of macroporous $TiO_2$ films and hollow $TiO_2$ tubes by soft-templating and their gas sensing applications have been reported recently. In these porous materials composed of assemblies of individual micro/nanostructures, the form of links or necks between individual micro/nanostructures is a critical factor to determine gas sensing properties of the material. However, a systematic study to clarify the role of links between individual micro/nanostructures in gas sensing properties of a porous metal oxide matrix is thoroughly lacking. In this work, we have demonstrated a fabrication method to prepare highly-ordered, embossed $TiO_2$ films composed of anatase $TiO_2$ hollow hemispheres via soft-templating using polystyrene beads. The form of links between hollow hemispheres could be controlled by $O_2$ plasma etching on the bead templates. This approach reveals the strong correlation of gas sensitivity with the form of the links. Our experimental results highlight that not only the surface-to-volume ratio of an ensemble material composed of individual micro/nanostructures but also the links between individual micro/nanostructures play a critical role in evaluating the sensing properties of the material. In addition to this general finding, the facileness, large-scale productivity, and compatability with semiconductor production process of the proposed fabrication method promise applications of the embossed $TiO_2$ films to high-quality sensors.

• 한국대기환경학회지
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• 제20권6호
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• pp.783-792
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• 2004

In this study, a thick-film semiconductor odor gas sensor for the detection of $CH_3$SH was developed using SnO$_2$ as the main substrate and was investigated in terms of its sensitivity and reaction time. In the process of manufacturing the sensor, Taguchi's design of experiment (DOE) was applied to analyze the effects of a variety of parameters, including the substrate, the additives and the fabrication conditions, systematically and effectively. Eight trials of experiments could be possible using the 27 orthogonal array for the seven factors and two levels of condition, which originally demands 128 trials of experiments without DOE. The additives of Sb$_2$O$_{5}$ and PdCl$_2$ with the H$_2$PtCl$_{6}$ ㆍ6$H_2O$ catalyst were appeared to be important factors to improve the sensitivity, and CuO, TiO$_2$, V$_2$O$_{5}$ and PdO were less important. In addition, TiO$_2$, V$_2$O$_{5}$ and PdO would improve the reaction time of a sensor, and CuO, Sb$_2$O$_{5}$, PdCl$_2$ and H$_2$PtCl$_{6}$ㆍ6$H_2O$ were negligible. Being evaluated simultaneously in terms of both sensitivity and reaction time, the sensor showed the higher performance with the addition of TiO$_2$ and PdO, but the opposite results with the addition of CuO, V$_2$O$_{5}$, Sb$_2$O$_{5}$ and PdCl$_2$. The amount of additives were superior in the case of 1% than 4%. H$_2$PtCl$_{6}$ㆍ6$H_2O$ would play an important role for the increase of sensor performance as a catalyst.nce as a catalyst.