• Title/Summary/Keyword: Alcohol gas sensors

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Alcohol Gas Sensors using Spray-coated Carbon Nanotube Thin Film (스프레이 코팅된 탄소나노튜브 박막을 이용한 알코올 가스 센서)

  • Kim, Seong-Jeen
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.21 no.9
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    • pp.783-788
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    • 2008
  • We suggest a CNT-based gas sensor for breath alcohol measurement. The sensor was composed of single-walled carbon nanotubes (SWCNTs) thin film on flexible PES (polyethersulfone) substrate, and the SWCNTs thin film was formed by multiple spray-coating with SWCNTs solution which was well-dispersed, highly controlled and functionalized in ethanol solvent. In this work, three types of SWCNTs thin films were deposited with changes in the number of spray-coatings to 20, 40 and 60 times in order to compare electrical response properties of the SWCNTs thin films. from the fabricated sensors, conductance and capacitance responses were measured and discussed. Alcohol gas sensors have been commercialized widely as gauge for breath alcohol measurement which is applicable to checking whether car drivers are drinking-driving or not. Our alcohol gas sensors showed good sensitivity and linearity even at room temperature.

Fabrication and Characteristics of Thick Film Alcohol Gas Sensors (후막형 알코올 센서의 제조 및 특성)

  • Choi Dong-Han
    • Proceedings of the IEEK Conference
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    • 2004.06b
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    • pp.387-390
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    • 2004
  • Thick film alcohol gas sensors were fabricated. Their electrical properties and gas sensing characteristics were investigated. The sensitivity of $1wt.\%$ Pd-doped ${\gamma}-Fe_2O_3$ thick film heat treated at $400^{\circ}C$, 2hrs was $74\%$ to 500ppm alcohol gas at the operating temperature of $250^{\circ}C$. The selectivity of the film to alcohol was good. It showed fast response time to low concentrations of alcohol in air, hence this sensor can be used as a breath sensor.

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Variation of Gas Selectivity by Silane binders in SWNT Gas sesnsors (SWNT 가스센서에서 실란 바인더에 의한 가스 선택성의 변화)

  • Lee, Ho-Jung;Kim, Seong-Jeen
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2010.03b
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    • pp.19-19
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    • 2010
  • We suggest CNT-based gas sensors for breath alcohol measurement. The sensors were composed of single-walled carbon nanotubes (SWNTs) thin film on glass substrate with simple process, and the SWNTs thin film as sensing layer was formed by multiple spray-coating with SWNT composites which was well-dispersed, highly controlled and differently functionalized by various binders (TEOS, MTMS, and VTMS) added in ethanol solvent. In this work, three different SWNTs thin films were made to compare their electrical response properties for alcohol vapor. From fabricated sensors, conductance responses were measured and discussed. In the result, our alcohol gas sensors showed an effective selectivity even at room temperature.

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Response properties of alcohol gas sensors depositing MWNT-composites by spray method (MWNT를 스프레이 코팅한 가스센서의 알콜 가스 응답 특성)

  • Choi, Young-Min;Gam, Byung-Min;Lee, Ho-Jung;Kim, Seong-Jeen
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2008.11a
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    • pp.382-383
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    • 2008
  • In this paper we presented experimental results of a gas sensor utilizing multi-walled carbon nanotube (MWNT)composites for the alcohol detection which is useful to checking drinking and driving, for example. The MWNT-composites were deposited using spray method on PES substrates suitable for use in low-cost and flexible sensors. We observed the variation of conductance from the sensors exposed to alcohol vapors evaporated at 37C equal to the human body temperature to match real condition. As the result, the conductance was decreased with the increase of ethanol vol% diluted in water. The sensors showed good sensitivity and linearity.

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Development of alcohol gas sensors measurable at room temperature (상온에서 측정 가능한 음주 측정용 알코올 가스 센서)

  • Jeon, Byung-Hyun;Lee, Ju-Hyuk;Kim, Seong-Jean;Lee, Cheol-Jin;Choi, Bok-Gil
    • Proceedings of the KIEE Conference
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    • 1999.07g
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    • pp.3265-3267
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    • 1999
  • Capacitance-type alcohol gas sensors using porous silicon (PS) layer as sensitive film were fabricated to measure low alcohol gas concentration. Though sensors using porous silicon layer have show high sensitivity by large internal surface area, there is still much room for improvement to measure low breath alcohol concentration especially at room temperature. In this work, to discuss the response properties against exposure to organic vapor for breath alcohol measurements on the basis of experimental results. we measured the variation of the capacitance for the range of 0 to 0.5% alcohol concentration, and observed the improvement of sensitivity by illumination of UV light. In addition, the effect of CO2 and N2 gases involved commonly in exhaling breath was estimated, and the same procedure against methanol vapor was executed to compare qualitatively with the capacitance characteristics by alcohol vapor.

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Improvement of Sensitivity in Porous Silicon Alcohol Gas Sensors by UV Light (자외선조사에 의한 다공질 실리콘 알코올 센서의 감도 개선)

  • Kim, Seong-Jin;Choe, Bok-Gil
    • The Transactions of the Korean Institute of Electrical Engineers C
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    • v.48 no.9
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    • pp.676-680
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    • 1999
  • To do breath alcohol measurement, a sensor is necessary that it can detect low alcohol gas concentration of 0.01% at least. In this work, a capacitance-type alcohol gas sensor using porous silicon layer is developed to measure low alcohol gas concentration. The sensor using porous silicon layer has some sensitivity at room temperature by very large effective surface area, but there is still much room for improvement. In this experiment, we measured the capacitance of the sensor under 254 nm UV light on the porous silicon layer, in which alcohol solution was kept in a flask at 25, 35, and $45^{\circ}C$ by a heater. As the result, the improvement of sensitivity by illuminating UV light was observed. The increasing rate of the capacitance was shown to be double more than those measured under UV-off state. It is supposed that UV light activates response of the oriental and interfacial polarizations which have slow relaxation time for AC field.

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Analysis of biomarkers with tunable infrared gas sensors (가변 파장형 적외선 가스 센서에 의한 생체표지자 분석)

  • Yi, Seung Hwan
    • Journal of Sensor Science and Technology
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    • v.30 no.5
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    • pp.314-319
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    • 2021
  • In this study, biomarkers were analyzed and segmented using tunable infrared gas sensors after performing the principal component analysis. The free spectral range of the device under test (DUT) was around 30 nm and DUT-5580 yielded the highest output voltage property among the others. The biomarkers (isoprophyl alcohol, ethanol, methanol, and acetone solutions) were sequentially mixed with deionized water and their mists were carried into the gas chamber using high-purity nitrogen gas. A total of 17 different mixed gases were tested with three tunable infrared gas sensors, namely DUT-3144, DUT-5580, and DUT-8010. DUT-8010 resolved the infrared absorption spectra of whole mixed gases. Based on the principal component analysis with each DUT and their combinations, each mixed gas and the trends in increasing gas concentration could be well analyzed when the contributions of the eigenvalues of the first and second were higher than 70% and 10%, respectively, and their sum was greater than 90%.

The effect of binder in SWNT solution to gas selectivity of CNT-based gas sensors (가스센서로써 탄소나노튜브 용액속에 바인더가 가스 선택성에 미치는 효과)

  • Lee, Ho-Jung;Gam, Byung-Min;Choi, Young-Min;Kim, Seong-Jeen
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2008.11a
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    • pp.404-405
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    • 2008
  • In this work, we investigated the effect of the functionalized SWNT-polymer composites for increasing sensitivity and imparting selectivity to nanotube sensors. To do this, CNT -based gas sensors were fabricated with two types of dispersed SWNT solution involving different polymer resin of TEOS (Tetraethyl orthosilicate) or MTMS (Methyl trimethoxysilane) which is blended to adhere to substrate well. As the surfaces of TEOS and MTMS surrounding SWNTs remain functionalized to -OH and $-CH_3$ groups respectively after hardening, gas adsorption will be affected differently according to the type of gases. In the experiment, we examined the response of electrical conductance for alcohol vapour gas. As the result, the conductance in the sensors using TEOS decreased considerably while that of MTMS was nearly invariable.

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Fabrication of the SnO2 thin-film gas sensors using an R.F. magnetron sputtering method and their alcohol gas-sensing characterization (R.F. Magnetron Sputtering 법을 이용한 SnO2 박막 센서의 제조 및 알콜 감도 특성)

  • Park, Sang-Hyoun;Kang, Ju-Hyun;Yoo, Kwang-Soo
    • Journal of Sensor Science and Technology
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    • v.14 no.2
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    • pp.63-68
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    • 2005
  • The nano-grained Pd or Pt-doped $SnO_{2}$ thin films were deposited on the alumina substrate at ambient temperature or $300^{\circ}C$ by using an R.F. magnetron sputtering system and then annealed at $650^{\cir}C$ for 1 hour or 4 hours in air. The crystallinity and microstructure of the annealed films were analyzed. A grain size of the thin films was 30 nm to 50 nm. As a result of gas sensitivity measurements to an alcohol vapor of $36^{\circ}C$, the 2 wt.% Pt-doped $SnO_{2}$ thin-film sensor deposited at $300^{\circ}C$ and annealed at $650^{\circ}C$ for 4 hours showed the highest sensitivity.

Study on Porous Silicon Sensors to Measure Low Alcohol Concentration (저농도 알코올 측정을 위한 다공질 실리콘 센서에 관한 연구)

  • Kim Seong-Jeen
    • Journal of the Korean Electrochemical Society
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    • v.2 no.3
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    • pp.130-133
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    • 1999
  • In this work, a capacitance-type alcohol gas sensor using porous silicon layer is developed to apply for breath alcohol measurement and its characteristics are estimated at room temperature. Current alcohol sensors using metal oxides such as tin-oxide are not only difficult to measure low alcohol concentration, but also should heat at $200\;to\;400^{\circ}C$ to improve the sensitivity. But the sensor using porous silicon layer has good sensitivity even at room temperature by very large effective surface area and suitable structure to fabricate integrated micro sensors. In the experiment, the capacitance was measured for the range of 0 to $0.5\%$ alcohol concentration with the interval of $0.05\%$, in which alcohol solution was kept at 25, 36, and $45^{\circ}C$ by a heater. As the result, good linearity was observed and the capacitance increased about 1.1, 2.6 and $4.6\%$ per the increment of $0.1\%$ alcohol concentration each temperature, respectively, at the frequency of 120 Hz.