• Journal of Auto-vehicle Safety Association
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• v.7 no.2
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• pp.39-43
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• 2015

NDIR (Non-dispersive infrared Rays) alcohol sensor has been prototyped and its temperature characteristics were measured. In order to design novel optical alcohol sensor, elliptical structures with one common foci were modeled and analyzed their optical properties. After analyzing elliptic optical structures, a prototype alcohol sensor module was tested according to the temperature variations from $-20^{\circ}C$ to $35^{\circ}C$. The offset voltages of alcohol sensor decreased from 1.1056 V at the temperature $-20^{\circ}C$ to 0.7339 V at $35^{\circ}C$. However, the highest sensitivity of alcohol sensor showed about $303{\mu}V/ppm$ at room temperature.

• Korean Journal of Food Science and Technology
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• v.27 no.2
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• pp.266-269
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• 1995

In order to measure alcohol contents with speed and accuracy, alcohol sensor was prepared. Alcohol sensor was made by connecting with oxygen electrode after immobilized alcohol oxidase on nylon net with glutaraldehyde. Alcohol was determined by changing the rate of dissolved oxygen consumption using D.O. analyzer. Alcohol contents in alcoholic beverages were determined under the optimum conditions. The results were 0.71% in low-alcohol beverage, $4{\sim}5%$ in beers, 10.06% in wine, 16.12% in chungju, 25.71% in soju, and 6.18% in takju, respectively. The values by alcohol sensor showed an excellent correlation(r=0.999) with GC method.

• 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.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.61 no.9
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• pp.1358-1361
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• 2012

This paper presents a study on the analysis for activation time and threshold value of heat detection sensor using HRR(Heat Release Rate). And it is represented to quantity of heat to activate heat detection sensor. The experiment is conducted to measure activation time and HRR of fire detection sensor burning alcohol and n-heptane. In order to burn the alcohol and n-heptane using $43.5cm(L){\times}43.5cm(W){\times}5cm(D)$ and $33cm(L){\times}33cm(L){\times}5cm(D)$ steel pan and the quantity of alcohol and n-heptane are 2.5 L and 650 g, respectively. The results show that peak HRR are in case of alcohol 66.13 kW and in case of n-heptane 151.64 kW, respectively. Total heat releases of heat detection sensor are in case of alcohol approximately 20.7 MJ and in case of n-heptane approximately 18 MJ, respectively.

• 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.

• Journal of Integrative Natural Science
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• v.3 no.2
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• pp.117-121
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• 2010

Silicon quantum dots base on photoluminescent porous silicon were prepared from an electrochemical etching of n-type silicon wafer (boron-dopped<100> orientation, resistivity of 1~10 ${\Omega}-cm$) and used as a alcohol sensor. Silicon quantum dots displayed an emission band at the wavelength of 675 nm with an excitation wavelength of 480 nm. Photoluminescence of silicon quantum dots was quenched in the presence of alcohol vapors such as methanol, ethanol, and isopropanol. Quenching efficiencies of 21.5, 32.5, and 45.8% were obtained for isopropanol, ethanol, and methanol, respectively. A linear relationship was obtained between quenching efficiencies and vapor pressure of analytes used. Quenching photoluminescence was recovered upon introducing of fresh air after the detection of alcohol. This provides easy fabrication of alcohol sensor based on porous silicon.

• 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.

• Journal of Advanced Navigation Technology
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• v.24 no.6
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• pp.627-632
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• 2020

In this paper, we have studied a development of a humidity sensor using a microwave sensor based on a microstrip defected ground structure coated with polyvinyl alcohol. A high-sensitivity microwave sensor, which is sensitive to the changes in the permittivity of the material under test, is designed by adding an interdigital capacitor-shaped defected ground structure to the ground plane of a microstrip line. Polyvinyl alcohol, a polymer material whose permittivity varies depending on humidity, is coated with a thin thickness on the defected ground structure of the proposed microwave sensor, and the changes in the resonance frequency and magnitude of the transmission coefficient for the microwave sensor according to humidity are measured. When relative humidity increases from 40% to 80% in 10% increments at a temperature of 25 degrees using a temperature/humidity chamber, the resonant frequency of the transmission coefficient decreases from 1.475 GHz to 1.449 GHz, and the magnitude is increased from -32.90 dB to -25.67 dB.

• 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.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.16 no.12S
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• pp.1232-1236
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• 2003

In this work, we fabricated a gas-sensing device based on porous silicon(PS), and its C-V properties were investigated for sensing alcohol vapor. The structure of the sensor consists of thin Au/oxidized PS/PS/P-Si/Al, where the p-Si is etched anisotropically to be prepared into a membrane-shape. We used alcohol gases vaporized from different alcohol (or ethanol) solutions mixed with pure water at 36$^{\circ}C$, similarly with an alcohol breath measurement to check drunk driving. As the result, I-V curves showed typical tunneling property, and C-V curves were shaped like those of a MIS (metal-insulator-semiconductor) capacitor, where the capacitance in accumulation was increased with alcohol vapor concentration.