• Journal of Sensor Science and Technology
• /
• v.26 no.3
• /
• pp.168-172
• /
• 2017

A nondispersive infrared (NDIR) ethanol gas sensor was prototyped with ASIC implemented thermopile sensor, which included a temperature sensor and two ellipsoidal waveguide structures. The temperature dependency of the two ethanol sensors (with partially blocked and intact structures) has been characterized. The two ethanol gas sensors showed linear output voltages initially when varying the ambient temperature from 253 K to 333 K. The slope of the temperature sensor presented a constant value of 15 mV/K. After temperature compensation, the ethanol gas sensor estimated ethanol concentrations with larger errors of 20 to 25% below 200 ppm. However, the estimation errors were reduced to between -10 and +1 % from 253 K to 333 K above 200 ppm ethanol gas concentration in this research.

• Journal of Sensor Science and Technology
• /
• v.33 no.2
• /
• pp.70-77
• /
• 2024

In this study, a fluorescent ethanol sensor is developed to determine the ethanol concentration in the liquid phase. The sensor is developed using a complex of resazurin (RA)/resorufin (RO) and a hydrotalcite (HT) catalyst in a sol-gel matrix of methyltrimethoxysilane (MTMS) to produce a fluorescent ethanol-sensing membrane (RA/RO^*HT membrane). The operation mechanism of the RA/RO^*HT membrane is based on (i) the oxidation of ethanol to acetaldehyde and (ii) the reduction of RA to RO, through electron flows followed by EtOH ↔ HT ↔ RA/RO ↔ EtOH interactions. These possible redox reactions can lead to an increased fluorescence intensity of the RA/RO^*HT membrane as the ethanol concentration increases. The RA/RO^*HT membrane shows a linear detection range of 1-20 vol.% EtOH with limit of detection (LOD) of 0.178%. Additionally, the RA/RO^*HT membrane has high sensitivity and accuracy for determining the alcohol content in several Korean alcoholic beverages.

• Journal of Sensor Science and Technology
• /
• v.27 no.1
• /
• pp.47-54
• /
• 2018

In this paper, we describe the thermal characteristics of the output voltages of ethanol gas sensor according to the amount of radiation incident on the infrared sensors located at each focal point of two elliptical waveguides. In order to verify the output characteristics of the gas sensor according to the amount of incident light on the infrared sensor, two combinations of sensor modules were fabricated. Hydrophobic thin film is deposited on one of the reflectors of sensor modules and one of the two infrared sensors was equipped with a hollow disk (10 Ø), and the temperature characteristics of the infrared sensor equipped with the hollow disk (10 Ø) and the infrared sensor without the disk were tested. The temperature was varied from 253 K to 333 K at 10 K intervals based on 298 K. The properties of ethanol gas sensor have been identified with respect to varying temperature for a range of ethanol concentration from 0 ppm to 500 ppm. In the case of an infrared sensor equipped with a hollow disk (10 Ø), the output voltage of the sensor decreased by 0.8 mV and 1 mV, respectively, as the temperature increased. Conversely, the output voltage of the diskless infrared sensor showed an average increase of 67 mV and 57 mV as the temperature increased. The ethanol concentrations estimated on the basis of results show an error of more than 10 % for less than 100 ppm concentration. However, if the ethanol concentration exceeds 100 ppm, the gas concentration can be estimated within the range of ${\pm}10%$.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.22 no.12
• /
• pp.1089-1094
• /
• 2009

Carbon nanotubes (CNTs) have excellent electrical, chemical stability, mechanical and thermal properties. In this paper, networks of Multi-walled carbon nanotube (MWCNT) materials were investigated as resistive gas sensors for ethanol ($C_2H_5OH$) detection. Sensor films were fabricated by air spray method for the multi-walled CNTs solution on glass substrates. Sensors were characterized by resistance measurements in the sensing system, in order to find the optimum detection properties for the ethanol gas molecular. The film that was sprayed with the MWCNT dispersion for 60 see, was 300 nm thick. And the electric resistivity is $2{\times}10^{-2}\;{\Omega\cdot}cm$. Also, the sensitivity and the linearity of MWVNT sensor for ethanol gas are 0.389 %/sec and 17.541 %/FS, respectively. The MWCNT film was excellent in the response for the ethanol gas molecules and its reaction speed was very fast, which could be using as ethanol gas sensor. The conductance of the fabricated sensors decreases when the sensors are exposed to ethanol gas.

• Journal of Sensor Science and Technology
• /
• v.15 no.6
• /
• pp.457-461
• /
• 2006

To use the porous silicon as gas sensors, we made the MOPS structure from the porous silicon with Al evaporation and investigated the sensing characteristic of ethanol. When the MOPS structure is in contact with ethanol gas, the maximum peak of PL changes and it return to original intensity without contact. The MOPS structure had response time 0.78s and recovery time 4.13s when it is in contact with ethanol, which satisfied the required sensor standards. Further complimentary researches, however, are required to investigate the contact mechanism between MOPS structure and ethanol and to solve the surface contamination problem.

• Journal of Sensor Science and Technology
• /
• v.23 no.3
• /
• pp.192-196
• /
• 2014

The effects of additives on gas sensing properties of $In_2O_3$ ethanol gas sensor were investigated. Gas sensors were fabricated by the painting method. The $In_2O_3-La_2O_3-Pt$ sensor heat treated $400^{\circ}C$ displayed fast response and recovery behavior with a maximum sensitivity to ethanol gas in air at an operating temperature of $300^{\circ}C$.

• Journal of Advanced Navigation Technology
• /
• v.26 no.6
• /
• pp.510-515
• /
• 2022

In this paper, a microstrip patch sensor antenna (MPSA) for detecting the concentration of an ethanol-water solution in a microliter volume is proposed. A rectangular slot was added at the radiating edge of the patch to increase the sensitivity to the relative permittivity change. To improve a low input resistance caused by placing an ethanol-water solution, which is a polar liquid with high dielectric constant and high loss tangent, on the patch, a quarter-wave impedance transformer was added between the 50-ohm feedline and the patch, and the MPSA was fabricated on a 0.76 mm-thick RF-35 substrate. A cylindrical container was made of acryl, and 15 microliters of the ethanol-water solution was tested from 0% to 100% of ethanol concentration at 20% intervals. Experiment results show that the resonant frequency increased from 1.947 GHz to 2.509 GHz when the ethanol concentration of the ethanol-water solution was increased from 0% to 100%, demonstrating the performance as a concentration detecting sensor.

• Journal of Sensor Science and Technology
• /
• v.16 no.6
• /
• pp.428-433
• /
• 2007

$SnO_{2}$-based thick film ethanol gas sensors were fabricated on alumina substrates and their ethanol gas sensing characteristics were investigated. The film sintered at $400^{\circ}C$ for 2 hrs. showed the highest sensitivity to ethanol gas and the sensitivity of the film to 1000 ppm ethanol gas in air was 97 % at an operating temperature of $250^{\circ}C$. The addition of $Fe_{2}O_{3}$ to $SnO_{2}$ enhanced the sensitivity by changing the type and number of surface acidic/basic sites.

• Journal of the Korean institute of surface engineering
• /
• v.48 no.5
• /
• pp.238-244
• /
• 2015

$TiO_2$ nanowires were synthesized by hydrothermal method for the application to ethanol gas sensor. $TiO_2$ nanowires were decorated with Au nanoparticles to improve the sensitivity to ethanol gas. Scanning electron microscopy and Transmission electron microscopy revealed that the synthesized nanowires had diameters and lengths of approximately 100 - 200 nm and a few micrometers, respectively. Size of the Au nanoparticles decorated on the $TiO_2$ nanowires was observed to be in the range of 10 - 20 nm. X-ray diffraction confirmed that the decorated nanowires were composed of anatase-, rutile-$TiO_2$, and Au. The sensitivities of $TiO_2$ nanowires sensors decorated with Au were approximately 1.1 - 3.65 times as high as those of as-synthesized $TiO_2$ sensors for the ethanol concentration of 5 - 100 ppm at $200^{\circ}C$. The mechanism of the improved ethanol gas sensing of the $TiO_2$ nanowires decorated with Au nanoparticles is discussed.

• Journal of Sensor Science and Technology
• /
• v.22 no.6
• /
• pp.444-449
• /
• 2013

ZnO-based ethanol gas sensors were fabricated by the painting method and their electrical and ethanol gas sensing characteristics were investigated. The ZnO-Pt (1 wt.%) film heat treated at $400^{\circ}C$, for 2 hrs. in air showed the highest sensitivity to ethanol gas in air at an operating temperature of $250^{\circ}C$ The sensitivity of the gas sensors to 1000 ppm ethanol in air at $250^{\circ}C$ was 8.7 and rising time and falling time of the gas sensors were 3.12 minutes and 25 minutes, respectively.