• Title/Summary/Keyword: NO gas sensor

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Fabrication and Characteristics of Surface-Acoustic-Wave Sensors for Detecting $NO_2$ GaS ($NO_2$ 가스 감지를 위한 표면탄성파 센서의 제작 및 특성)

  • Choi, D.H.
    • Journal of Sensor Science and Technology
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    • v.8 no.2
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    • pp.108-114
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    • 1999
  • Surface acoustic wave (SAW) device is very attractive for gas sensor applications because of their small size, low cost, high sensitivity, and good reliability. A dual delay line surface acoustic wave $NO_2$ gas sensors have been designed and fabricated on the $LiTaO_3$ piezoelectric single crystal substrate. The capacitance of the fabricated IDTs was 326.34pF at the frequency of 79.3MHz. The maximum reflection loss of the impedence-matched IDTs was -16.74dB at the frequency of 79.3MHz. The SAW oscillator was constructed and the stable oscillation was obtained by controlling the gain of rf amplifier properly. The oscillation frequency shift of the SAW oscillator to the $NO_2$ gas was 28Hz/ppm.

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NO2 Gas Sensing Properties of Nano-Sized In2O3 Doped WO3 Powders Prepared from Polymer Solution Route (폴리머 용액법에 의한 In2O3 첨가 나노 WO3 분말 합성 및 NO2 가스 센서 특성)

  • Kim, Dong Min;Lee, Sang-Jin
    • Korean Journal of Materials Research
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    • v.28 no.1
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    • pp.12-17
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    • 2018
  • $In_2O_3$ doped $WO_3$ powders were prepared by a polymer solution route and their $NO_2$ gas sensing properties were analyzed. The synthesized powders showed nano-sized particles with specific surface areas of $6.01{\sim}21.5m^2/g$ and the particle size and shape changed according to the content of $In_2O_3$. The gas sensors fabricated with the synthesized powders were tested at operating temperatures of $400{\sim}500^{\circ}C$ and 100~500 ppm concentrations of $NO_2$ atmosphere. The particle size and $In_2O_3$ content affected on the initial sensor resistance in an air atmosphere. The highest sensitivity (8.57 at $500^{\circ}C$), which was 1.77 higher than the sensor consisting of the pure $WO_3$ sample, was measured in the 0.5 mol% $In_2O_3$ doping sample. In addition, the response time and recovery time were improved by the addition of $In_2O_3$.

Nitrogen Monoxide Gas Sensing Properties of Copper Oxide Thin Films Fabricated by a Spin Coating Method (스핀코팅법으로 제작한 산화구리 박막의 일산화질소 가스 감지 특성)

  • Hwang, Hyeonjeong;Kim, Hyojin;Kim, Dojin
    • Korean Journal of Materials Research
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    • v.25 no.4
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    • pp.171-176
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    • 2015
  • We present the detection characteristics of nitrogen monoxide(NO) gas using p-type copper oxide(CuO) thin film gas sensors. The CuO thin films were fabricated on glass substrates by a sol-gel spin coating method using copper acetate hydrate and diethanolamine as precursors. Structural characterizations revealed that we prepared the pure CuO thin films having a monoclinic crystalline structure without any obvious formation of secondary phase. It was found from the NO gas sensing measurements that the p-type CuO thin film gas sensors exhibited a maximum sensitivity to NO gas in dry air at an operating temperature as low as $100^{\circ}C$. Additionally, these CuO thin film gas sensors were found to show reversible and reliable electrical response to NO gas in a range of operating temperatures from $60^{\circ}C$ to $200^{\circ}C$. It is supposed from these results that the p-type oxide semiconductor CuO thin film could have significant potential for use in future gas sensors and other oxide electronics applications using oxide p-n heterojunction structures.

A Study on the development of gas metering valve system (가스 계량 밸브 시스템의 개발에 관한 연구)

  • Choi, Young-Gyu
    • The Journal of Korea Institute of Information, Electronics, and Communication Technology
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    • v.7 no.4
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    • pp.200-204
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    • 2014
  • LPG is used in the home would have to depend on the provider, because there is no method for measuring the capacitance. In addition, by measuring the gas capacities can not be known because of the LPG gas replacement time and requires an alarm for replacement. In this study, and that the gas capacities to the trusted user and the supplier, in order to know when it is time to change to LPG gas by applying a Hall effect sensor developed a gas capacities measurement the valve system.

Potentiometric NOx sensors for automotive exhaust using YSZ(yittria stabilized zirconia) electrolyte (YSZ 전해질을 이용한 농담전지식 자동차용 NOx센서)

  • Park, Jin-Su;Park, Kwang-Chol;Park, C.O.
    • Journal of Sensor Science and Technology
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    • v.16 no.6
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    • pp.434-440
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    • 2007
  • Two kinds of new NOx sensing mechanism was proposed and examined. One of those was potentiomtric sensor based on the measurement of decomposed oxygen from NO using YSZ porous diffusion barrier and Pd catalytic electrode. The sensor based on decomposed oxygen measurement responded to the range of 300 - 1000 ppm NO in $N_{2}$ environment and the sensitivities were coincident with theoretical values at 700 and $800^{\circ}C$ but the decomposition rate depended on gas flow rate. The other sensor was equilibrium potentiometric type using $Gd_{2}O_{3}$-nitrates solid solution as sensing material. The sensor using $Gd_{2}O_{3}$-nitrates solid solution was suitable for NOxxsensing at $700^{\circ}C$ in 5 % oxygen and the sensitivity was 19.3 mV/decade. However, long term stability of the sensing material at high temperature was not sufficient.

Selective NO2 Sensors Using MoS2-MoO2 Composite Yolk-shell Spheres

  • Jeong, Seong Yong;Choi, Seung Ho;Yoon, Ji-Wook;Won, Jong Min;Kang, Yun Chan;Park, Joon-Shik;Lee, Jong-Heun
    • Journal of Sensor Science and Technology
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    • v.24 no.3
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    • pp.151-154
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    • 2015
  • The gas sensing characteristic of $MoS_2-MoO_2$ composite yolk-shell spheres were investigated. $MoO_3$-carbon composite spheres were prepared by ultrasonic spray pyrolysis of aqueous droplets containing Mo-source and sucrose in nitrogen, which were converted into $MoO_3$ yolk-shell spheres by heat treatment at $400^{\circ}C$ in air. Subsequently, $MoS_2-MoO_2$ composite yolk-shell spheres were prepared by the partial sulfidation of $MoO_3$. The $MoS_2-MoO_2$ composite yolk-shell spheres showed relatively low and irreversible gas sensing characteristics at < $200^{\circ}C$. In contrast, the sensor showed high and reversible response (S=resistance ratio) to 5 ppm $NO_2$ (S=14.8) at $250^{\circ}C$ with low cross-responses (S=1.17-2.13) to other interference gases such as ethanol, CO, xylene, toluene, trimethylamine, $NH_3$, $H_2$, and HCHO. The $MoS_2-MoO_2$ composite yolk-shell spheres can be used as reliable sensors to detect $NO_2$ in a selective manner.

SnO2 Semiconducting Nanowires Network and Its NO2 Gas Sensor Application (SnO2 반도체 나노선 네트웍 구조를 이용한 NO2 가스센서 소자 구현)

  • Kim, Jeong-Yeon;Kim, Byeong-Guk;Choi, Si-Hyuk;Park, Jae-Gwan;Park, Jae-Hwan
    • Korean Journal of Materials Research
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    • v.20 no.4
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    • pp.223-227
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    • 2010
  • Recently, one-dimensional semiconducting nanomaterials have attracted considerable interest for their potential as building blocks for fabricating various nanodevices. Among these semiconducting nanomaterials,, $SnO_2$ nanostructures including nanowires, nanorods, nanobelts, and nanotubes were successfully synthesized and their electrochemical properties were evaluated. Although $SnO_2$ nanowires and nanobelts exhibit fascinating gas sensing characteristics, there are still significant difficulties in using them for device applications. The crucial problem is the alignment of the nanowires. Each nanowire should be attached on each die using arduous e-beam or photolithography, which is quite an undesirable process in terms of mass production in the current semiconductor industry. In this study, a simple process for making sensitive $SnO_2$ nanowire-based gas sensors by using a standard semiconducting fabrication process was studied. The nanowires were aligned in-situ during nanowire synthesis by thermal CVD process and a nanowire network structure between the electrodes was obtained. The $SnO_2$ nanowire network was floated upon the Si substrate by separating an Au catalyst between the electrodes. As the electric current is transported along the networks of the nanowires, not along the surface layer on the substrate, the gas sensitivities could be maximized in this networked and floated structure. By varying the nanowire density and the distance between the electrodes, several types of nanowire network were fabricated. The $NO_2$ gas sensitivity was 30~200 when the $NO_2$ concentration was 5~20ppm. The response time was ca. 30~110 sec.

Fabrication and Characteristics of Micro Platform for Micro Gas Sensor with Low Power Consumption (마이크로 가스센서의 저전력 구동을 위한 마이크로 플랫폼의 제작과 특성)

  • Jang, Woong-Jin;Park, Kwang-Bum;Kim, In-Ho;Park, Soon-Sup;Park, Hyo-Derk;Lee, In-Kyu;Park, Joon-Shik
    • Journal of Sensor Science and Technology
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    • v.20 no.5
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    • pp.317-321
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    • 2011
  • A Micro platform for micro gas sensor consisted of micro heater, insulator, and sensing electrode on 2 ${\mu}m$ thick $SiN_x$ membrane. Three types of micro platforms were designed and fabricated with membrane sizes. Total size of micro platform was 2.6 mm by 2.6 mm. Measured power consumptions were 28 mW, 28 mW, and 32.5 mW for Type 1, Type 2, and Type 3. At this moment, temperatures of membranes on the platforms were $295^{\circ}C$, $297^{\circ}C$, and $296^{\circ}C$, respectively. Fabricated micro platform considered appropriate to apply for low power consumption micro gas sensor. Micro gas sensors were prepared by the sequence that $SnO_2$ nanopowder pastes were dropped on membrane of Type 1 platforms, dried in oven, heat-treated with micro heaters in platforms. One of the micro gas sensors was tested for gas response to 1157 ppm, 578 ppm, and 231 ppm of methane and 1.68 ppm, 0.84 ppm, and 0.42 ppm of $NO_2$.

Synthesis and Characterization of Zinc Oxide Nanorods for Nitrogen Dioxide Gas Detection

  • Park, Jong-Hyun;Kim, Hyojin
    • Journal of the Korean institute of surface engineering
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    • v.54 no.5
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    • pp.260-266
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    • 2021
  • Synthesizing low-dimensional structures of oxide semiconductors is a promising approach to fabricate highly efficient gas sensors by means of possible enhancement in surface-to-volume ratios of their sensing materials. In this work, vertically aligned zinc oxide (ZnO) nanorods are successfully synthesized on a transparent glass substrate via seed-mediated hydrothermal synthesis method with the use of a ZnO nanoparticle seed layer, which is formed by thermally oxidizing a sputtered Zn metal film. Structural and optical characterization by x-ray diffraction (XRD), scanning electron microscopy (SEM), and Raman spectroscopy reveals the successful preparation of the ZnO nanorods array of the single hexagonal wurtzite crystalline phase. From gas sensing measurements for the nitrogen dioxide (NO2) gas, the vertically aligned ZnO nanorod array is observed to have a highly responsive sensitivity to NO2 gas at relatively low concentrations and operating temperatures, especially showing a high maximum sensitivity to NO2 at 250 ℃ and a low NO2 detection limit of 5 ppm in dry air. These results along with a facile fabrication process demonstrate that the ZnO nanorods synthesized on a transparent glass substrate are very promising for low-cost and high-performance NO2 gas sensors.

Vertically aligned cupric oxide nanorods for nitrogen monoxide gas detection

  • Jong-Hyun Park;Hyojin Kim
    • Journal of the Korean institute of surface engineering
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    • v.56 no.4
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    • pp.219-226
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    • 2023
  • Utilizing low-dimensional structures of oxide semiconductors is a promising approach to fabricate relevant gas sensors by means of potential enhancement in surface-to-volume ratios of their sensing materials. In this work, vertically aligned cupric oxide (CuO) nanorods are successfully synthesized on a transparent glass substrate via seed-mediated hydrothermal synthesis method with the use of a CuO nanoparticle seed layer, which is formed by thermally oxidizing a sputtered Cu metal film. Structural and optical characterization by x-ray diffraction (XRD), scanning electron microscopy (SEM), and Raman spectroscopy reveals the successful preparation of the CuO nanorods array of the single monoclinic tenorite crystalline phase. From gas sensing measurements for the nitrogen monoxide (NO) gas, the vertically aligned CuO nanorod array is observed to have a highly responsive sensitivity to NO gas at relatively low concentrations and operating temperatures, especially showing a high maximum sensitivity to NO at 200 ℃ and a low NO detection limit of 2 ppm in dry air. These results along with a facile fabrication process demonstrate that the CuO nanorods synthesized on a transparent glass substrate are very promising for low-cost and high-performance NO gas sensors.