• 한국전기전자재료학회논문지
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• 제21권9호
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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.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2004년도 하계종합학술대회 논문집(2)
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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.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2010년도 춘계학술대회 논문집
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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.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2008년도 추계학술대회 논문집 Vol.21
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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.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1999년도 하계학술대회 논문집 G
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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.

• 대한전기학회논문지:전기물성ㆍ응용부문C
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• 제48권9호
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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.

• 센서학회지
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• 제30권5호
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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%.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2008년도 추계학술대회 논문집 Vol.21
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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.

• 센서학회지
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• 제14권2호
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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.

• 전기화학회지
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• 제2권3호
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• pp.130-133
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• 1999

본 연구에서는 음주 측정에 적용할 수 있는 다공질 실리콘층으로 된 저농도의 캐퍼시턴스형 알코올 가스 측정용 센서를 제작하고, 상온에서 그 특성을 측정하였다. 기존의 $SnO_2$등의 금속 산화물 반도체를 이용한 센서는 저농도의 알코올을 정확하게 검지하기에 어려울 뿐만 아니라 감도를 높이기 위해 $200\~400^{\circ}C$로 가열이 필요하였다. 이에 비해 다공질 실리콘층을 이용한 센서는 넓은 표면적을 갖고 있어 상온에서도 감도가 양호할 뿐만 아니라 집적화 센서로 제작이 용이한 점을 갖고 있다. 실험은 증류수에 희석한 알코올 수용액을 체온과 같은 $36^{\circ}C$를 비롯하여 25와 $45^{\circ}C$로 유지한 상태에서 0에서 $0.5\%$의 농도범위에 대해서 $0.05\%$의 간격으로 120 Hz와 1 kHz의 두 주파수에서 측정하였다. 그 결과, 양호한 선형성과 함께 120 Hz의 주파수에서 측정하였을 때, $0.1\%$의 알코올 농도의 증분마다 $25,\;36,\;45^{\circ}C$의 알코올 수용액의 온도에 대해 각각 1.1, 2.6 및 $4.6\%$로 캐퍼시턴스의 증가율을 보였다.