• 제목/요약/키워드: $NO_2$ sensor

검색결과 606건 처리시간 0.034초

Sol-Coprecipitation 법에 의한 NO 감지용 $WO_3$ 센서 제조시 pH의 영향 (Influence of pH on Sensitivity of $WO_3$ NO gas sensor fabricated by Sol-Coprecipitation method)

  • 김석봉;이대식;이덕동;허증수
    • 센서학회지
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    • 제10권2호
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    • pp.118-124
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    • 2001
  • 입자들이 용액에 녹아있을 때 pH에 따라서 다른 zeta-potential을 가지게 되며, 이것은 입자의 분산상태에 영향을 주게 된다. NO 센서에서 $WO_3$ 입자의 크기는 감도에 큰 영향을 끼치므로 Sol-Coprecipitation법에 의한 $WO_3$ 센서 제조 시에 $WO_3$ precursor 상태에서의 pH의 영향을 알아보았다. 먼저 $WO_3$ precursor의 전기적 포텐셜을 측정하여 pH가 2에서 7로 변함에 따라 mobility가 증가하여 7일 때에 가장 큰 분산도를 가진 것을 알 수 있었고, 이는 powder 제조 후 입도 분석, 감지막의 XRD peak, 표면사진으로부터 확인 할 수 있었다. 결과적으로 감도 특성에도 영향을 끼쳐 pH=7에서 제조한 센서가 다른 pH에서 제조한 센서보다 감도가 우수한 것으로 나타났다.

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ZnO가 첨가된 TeO2 나노와이어의 합성 및 저농도(50 ppm) 이산화질소 가스 센싱 특성 (Synthesis and Low-concentration (50 ppm) NO2 Sensing Properties of Bare and ZnO (n) Decorated TeO2 (p) Nanowires)

  • 유동재;신가윤;엄완식;강석우;김은비;김형민;김현우
    • 한국재료학회지
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    • 제32권10호
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    • pp.435-441
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    • 2022
  • We report the synthesis and gas sensing properties of bare and ZnO decorated TeO2 nanowires (NWs). A catalyst assisted-vapor-liquid-solid (VLS) growth method was used to synthesize TeO2 NWs and ZnO decoration was performed using an Au-catalyst assisted-VLS growth method followed by a subsequent heat treatment. Structural and morphological analyses using X-ray diffraction (XRD) and scanning/transmission electron microscopies, respectively, demonstrated the formation of bare and ZnO decorated TeO2 NWs with desired phase and morphology. NO2 gas sensing studies were performed at different temperatures ranging from 50 to 400 ℃ towards 50 ppm NO2 gas. The results obtained showed that both sensors had their best optimal sensing temperature at 350 ℃, while ZnO decorated TeO2 NWs sensor showed much better sensitivity towards NO2 relative to a bare TeO2 NWs gas sensor. The reason for the enhanced sensing performance of the ZnO decorated TeO2 NWs sensor was attributed to the formation of ZnO (n)/ TeO2 (p) heterojunctions and the high intrinsic gas sensing properties of ZnO.

이산화질소 감지용 다중벽 탄소나노튜브 가스센서의 제작 및 감응 특성 (Fabrication and Sensing Characteristics of Multi-Walled Carbon Nanotube Gas Sensor for No2 Detection)

  • 조우성;문승일;김영조;이윤희;주병권
    • 한국전기전자재료학회논문지
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    • 제17권3호
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    • pp.294-298
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    • 2004
  • Carbon nanotubes(CNTs) were synthesized by thermal chemical vapor deposition(CVD) method. To fabricate CNT gas sensor, catalyst metal layer was deposited on microstructure. The CNT gas detecting layer was grown by thermal CVD method on the catalyst metal layer. In order to investigate the gas sensing characteristics of the fabricated CNT gas sensor, it was exposed in NO$_2$ gas and sensitivity, response, and recovery time were measured. As the result, this sensor has better reproductibility and faster recovery time than another CNT gas sensors.

Solid Electrochemical Method of Measuring Hydrogen Concentration with O2-/H+ Hetero-Ionic Junction

  • Chongook Park
    • 센서학회지
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    • 제33권2호
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    • pp.63-69
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    • 2024
  • A novel method for measuring hydrogen concentration is introduced, along with its working principle and a novel detection algorithm. This configuration requires no additional reference compartment for potentiometric electrochemical measurements; therefore, it is the most suitable for measuring dissolved hydrogen in the liquid phase. The sensor's electromotive force saturates at a certain point, depending on the hydrogen concentration during the heating process of the sensor operation. This dynamic temperature scanning method provides higher sensitivity than the constant temperature measurement method.

N-형 $WO_{3}$계 가스센서의 전기적 특성 (Electrical properties of n-type $WO_{3}$ based gas sensors)

  • 양종인;김일진;임한조;한상도;정관수
    • 센서학회지
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    • 제7권3호
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    • pp.188-196
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    • 1998
  • $WO_{3}$계 n-형 반도체 가스센서의 검지특성 및 전기적 특성을 조사하였다. 공기중에서 결합제가 첨가되지 않은 $WO_{3}:TiO_{2}$(4 wt. %) 센서의 낱알경계에서의 전위장벽의 크기는 0.26 V로 나타났으며, 결합제로서 $Al_{2}O_{3}$, PVA (polyvinyl alcohol ), silica sol이 첨가된 센서의 경우는 전위장벽이 각각 0.17, 0.22, 0.26 V로 관측되었다. 이들 시료를 $NO_{x}$가 120 ppm 첨가된 분위기에 노출시켰을 때, 결합제가 첨가되지 않은 센서의 경우는 낱알경계에서의 전위장벽이 0.59 V로 증가하였으며, 결합제로서 $Al_{2}O_{3}$, PVA, silica sol이 첨가된 경우는 전위장벽이 각각 0.43, 0.66, 0.52 V로 나타나, PVA가 첨가된 센서에서 전위장벽의 변화가 가장 높아 감도가 우수하게 되는 것을 알 수가 있었다. 한편 센서 최적 작동온도 이상의 온도에서 나타나는 감도의 감소는 흡착가스 입자의 탈착보다는 공기중에서 다결정이 보이는 저항의 온도 의존성에 따라 나타남이 판명되었다. 또한 결합제가 첨가되지 않은 센서와 결합제로서 Pt가 첨가된 센서의 경우, CO가 250 ppm 존재할 때까지도 전위장벽의 크기가 약 0.2 V로 공기중에서와 비슷한 크기를 나타내어, CO와 $NO_{x}$가 혼합된 분위기에서 $NO_{x}$만을 선택적으로 검지하는데 유리함이 밝혀졌다.

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

  • 박진수;박광철;박종욱
    • 센서학회지
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    • 제16권6호
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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
    • 센서학회지
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    • 제24권3호
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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.

SOI CMOS-Based Smart Gas Sensor System for Ubiquitous Sensor Networks

  • Maeng, Sung-Lyul;Guha, Prasanta;Udrea, Florin;Ali, Syed Z.;Santra, Sumita;Gardner, Julian;Park, Jong-Hyurk;Kim, Sang-Hyeob;Moon, Seung-Eon;Park, Kang-Ho;Kim, Jong-Dae;Choi, Young-Jin;Milne, William I.
    • ETRI Journal
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    • 제30권4호
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    • pp.516-525
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    • 2008
  • This paper proposes a compact, energy-efficient, and smart gas sensor platform technology for ubiquitous sensor network (USN) applications. The compact design of the platform is realized by employing silicon-on-insulator (SOI) technology. The sensing element is fully integrated with SOI CMOS circuits for signal processing and communication. Also, the micro-hotplate operates at high temperatures with extremely low power consumption, which is important for USN applications. ZnO nanowires are synthesized onto the micro-hotplate by a simple hydrothermal process and are patterned by a lift-off to form the gas sensor. The sensor was operated at $200^{\circ}C$ and showed a good response to 100 ppb $NO_2$ gas.

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상온에서 UV 활성화된 ZnS 나노와이어의 NO2 가스 검출 특성 (NO2 gas sensing properties of UV activated ZnS nanowires at room temperature)

  • 강우승
    • 한국표면공학회지
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    • 제47권6호
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    • pp.297-302
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    • 2014
  • ZnS nanowires were synthesized in order to investigate $NO_2$ gas sensing properties. They were grown on the sapphire substrate using ZnS powders. SEM (scanning electron microscopy) showed the diameter and length of the ZnS nanowires were approximately in the range of 50 - 100 nm and a few $10s\;{\mu}m$, respectively. They were also found to be composed of Wurtzite- structured single crystals from TEM (transmission electron microscopy) analysis. $NO_2$ gas sensing performance of the ZnS nanowire was measured with electrical resistance changes caused by $NO_2$ gas with a concentration of 1-5ppm. The sensor was UV treated with an intensity of $1.2mW/cm^2$ to facilitate charge carrier transfer. The responses of the ZnS nanowires to the $NO_2$ gas at room temperature, treated with UV of two different wavelengths of 365 nm and 254 nm, are measured to be 124.53 - 206.87 % and 233.97 - 554.83%, respectively. In the current work, the effect of UV treatment on the gas sensing performance of the ZnS nanowires was studied. And the underlying mechanism for the electrical resistance changes of the ZnS nanowires by $NO_2$ gas was also discussed.

탄소 나노튜브의 성장 및 후처리 조건에 따른 이산화질소 감지특성의 변화 (The Change of $NO_{2}$ Sensing Characteristics for Carbon Nanotubes with Growth and Post Treatment Conditions)

  • 이임력
    • 마이크로전자및패키징학회지
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    • 제13권4호
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    • pp.65-70
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    • 2006
  • CVD 및 PECVD법으로 탄소 나노튜브를 성장하고, 그 후 $400{\sim}500^{\circ}C$에서 산화 열처리한 센서의 이산화질소 감지특성을 $200^{\circ}C$ 및 1.5ppm의 이산화질소 농도 하에서 측정하였다. 탄소 나노튜브 센서의 전기저항은 온도 증가에 따라 감소하는 반도체 특성을 보였으며, 이산화질소 흡착에 따라 전기저항은 감소하였다. 공기 중의 수분은 센서감도에 영향을 주고 있으며, 센서를 마이크로파에 3분간 노출하면 센서의 특성은 저하되었다. 또한 CVD법으로 제조한 시편에 비하여 PECVD법으로 성장한 탄소 나노튜브 센서의 감도는 향상 되었다.

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