• Title/Summary/Keyword: Infrared gas sensor

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Temperature Compensation and Characteristics of Non-dispersive Infrared Alcohol Sensor According to the Intensity of Light (입사광량의 조절과 이에 따른 비분산 적외선 알코올 센서의 온도 특성과 보정)

  • Kim, JinHo;Cho, HeeChan;Yi, SeungHwan
    • Journal of Sensor Science and Technology
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    • v.27 no.1
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    • pp.47-54
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    • 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 ${\pm}10%$.

Properties of Non-dispersive infrared Ethanol Gas Sensors according to the Irradiation Energy

  • Kim, JinHo;Yi, SeungHwan
    • Journal of Sensor Science and Technology
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    • v.26 no.3
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    • pp.168-172
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    • 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.

Temperature Dependency of Non-dispersive Infrared Carbon Dioxide Gas Sensor by using Infrared Sensor for Compensation (보상용 적외선 센서를 사용한 비분산 적외선 이산화탄소 센서의 온도특성)

  • Yi, SeungHwan
    • Journal of Sensor Science and Technology
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    • v.25 no.2
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    • pp.124-130
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    • 2016
  • NDIR $CO_2$ gas sensor was built with ASIC implemented thermopile sensor which included temperature sensor and unique elliptical waveguide structures in this paper. The temperature dependency of dual infrared sensor module ($CO_2$ and reference IR sensors) has been characterized and its output voltage characteristics according to the temperature and gas concentration were proposed for the first time. NDIR $CO_2$ gas and reference IR sensors showed linear output voltages according to the variation of ambient temperatures from 243 K to 333 K and their slopes were 14.2 mV/K and 8.8 mV/K, respectively. The output voltages of temperature sensor also presented a linear dependency according to the ambient temperature and could be described with V(T)=-3.191+0.0148T(V). The output voltage ratio between $CO_2$ and reference IR sensors revealed irrelevant to the changes of ambient temperatures and gave a constant value around 1.6255 with standard deviation 0.008 at 0 ppm. The output voltage of $CO_2$ gas sensor at zero ppm $CO_2$ gas consisted of two components; one is caused by the HPB (half pass-band) of IR filter and the other is attributed to the part of $CO_2$ absorption wavelength. The characteristics of output voltages of $CO_2$ gas sensor could be accurately modeled with three parameters which are dependent upon the ambient temperatures and represented small average error less than 1.5% with 5% standard deviation.

Temperature Compensation of Nondispersive Infrared Gas Senor: Infrared Light Absorbance (비분산 적외선 가스 센서 온도 보상법: 적외선 흡수도)

  • Yi, SeungHwan
    • Journal of Sensor Science and Technology
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    • v.30 no.1
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    • pp.36-41
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    • 2021
  • The motivation of this paper is to easily analyze the properties of nondispersive infrared gas sensor that has more than two different optical path length and to suggest the criterion and definition of infrared light absorbance in order to minimize the measurement errors. With the output voltage ratios and the normalized derivatives of infrared ray (IR) absorbance, when the normalized derivatives of IR absorbance decreases from 0.28 to 0.10, the lower and higher limits of errors were decreased from -5.62% and 2.39% to -4.27% and 2.78%. When the normalized derivatives of IR absorbance were 0.10, the output voltage could be partitioned into two regions with one exponential equation and the temperature compensation error was less than 5%.

Analysis of Output Voltage Properties of Non-dispersive Infrared Gas Sensors According to Ambient Temperatures (주변 온도 영향에 따른 비분산 적외선 가스센서의 출력 특성 해석)

  • Park, Han-Gil;Yi, Seung-Hwan
    • Journal of Sensor Science and Technology
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    • v.27 no.5
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    • pp.294-299
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    • 2018
  • This article describes the output properties of non-dispersive infrared carbon dioxide($CO_2$) sensors resulting from the changes in ambient temperatures. After the developed sensor module was installed inside the gas chamber, the temperature was set to 267 K, 277 K, 300 K, and 314 K, and the concentrations of $CO_2$ gas were increased from 0 to 5,000 ppm. Then, the output voltage at each concentration was obtained. Through these experimental results, two observations were made. First, both the $CO_2$ sensor and the reference sensor showed an increase in the output voltages as the temperature rose from 0 ppm, Second, the full scale outputs of the $CO_2$ sensor grew as the temperature increased. The output characteristics were analyzed based on two factors: change in the radiant energy of the infrared light source and change in the absorptivity of $CO_2$ gas according to the ambient temperature. Additionally, temperature compensation methods were discussed.

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%.

Optical waveguide structure design of Non-dispersive Infrared (NDIR) CO2 gas sensor for high-sensitivity (이산화탄소 검출을 위한 고감도 비분산 적외선 가스센서의 광도파관 구조 설계)

  • Yoon, Jiyoung;Lee, Junyeop;Do, Namgon;Jung, Daewoon
    • Journal of Sensor Science and Technology
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    • v.30 no.5
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    • pp.331-336
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    • 2021
  • The Non-dispersive Infrared (NDIR) gas sensor has high selectivity, measurement reliability, and long lifespan. Thus, even though the NDIR gas sensor is expensive, it is still widely used for carbon dioxide (CO2) detection. In this study, to reduce the cost of the NDIR CO2 gas sensor, we proposed the new optical waveguide structure design based on ready-made gas pipes that can improve the sensitivity by increasing the initial light intensity. The new optical waveguide design is a structure in which a part of the optical waveguide filter is inclined to increase the transmittance of the filter, and a parabolic mirror is installed at the rear end of the filter to focus the infrared rays passing through the filter to the detector. In order to examine the output characteristics of the new optical waveguide structure design, optical simulation was performed for two types of IR-source. As a result, the new optical waveguide structure can improve the sensitivity of the NDIR CO2 gas sensor by making the infrared rays perpendicular to the filter, increasing the filter transmittance.

Temperature Compensation Algorithm of Nondispersive Infrared (NDIR) Gas Sensor (비분산 적외선 가스센서의 온도보상 알고리즘)

  • Park, Jong-Seon;Yi, Seung-Hwan
    • Journal of the Korean Institute of Gas
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    • v.15 no.4
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    • pp.51-55
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    • 2011
  • This paper describes the temperature compensation algorithm using thermopile detector for nondispersive infrared methane gas sensor. From the output voltage of thermistor that is attached onto the infrared detector, the ambient temperature was extracted. The effects of temperatures on the properties of sensor module (the characteristics of narrow bandpass filter, optical cavity and infrared lamp, and gas absorption coefficient times optical path length) have been introduced in order to implement the temperature compensation algorithm. Even though the measurement error of developed sensor module was in the range of $\pm$ 1,500 ppm, after programming the temperature compensation algorithm, the developed sensor module shows a high accuracy less than +180 ppm error within $20^{\circ}C$ temperature variation.

A Multi-Channel Gas Sensor Using Fabry-Perot Interferometer-Based Infrared Spectrometer

  • Choi, Ju Chan;Lee, June Kyoo;Kong, Seong Ho
    • Journal of Sensor Science and Technology
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    • v.21 no.6
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    • pp.402-407
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    • 2012
  • We report a Fabry-Perot interferometer (FPI)-based multi-channel micro-spectrometer used for multi-gas measurement in the spectral range of $3-5{\mu}m$ and its gas sensing performance. The fabricated infrared (IR) spectrometer consists of two parts: an FPI on the top side for selective IR filtering and a $V_2O_5$-based IR detector array on the bottom side for the detection of the filtered IR. Experimental results show that the FPI-based multi-channel gas sensor has reliability and selectivity for simultaneously detecting environmentally harmful gases such as $CH_4$, $CO_2$, $N_2O$ and CO in the spectral range of $3-5{\mu}m$. The fabricated FPI-based multi-channel gas sensor also demonstrated that a reliable and selective detection of gas concentrations ranging from 0 to 500 ppm is feasible. In addition, the electrical characteristics demonstrate a superior response performance in regards to the selectivity in the multi-target gases.

Temperature Dependency of Non-dispersive Infrared Carbon Dioxide Gas Sensor by Using White-Cell Structure (White-Cell 구조를 응용한 비분산 적외선 이산화탄소 센서의 온도특성)

  • Yi, SeungHwan;Park, YoungHwan;Lee, JaeKyung
    • Journal of Sensor Science and Technology
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    • v.25 no.5
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    • pp.377-381
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    • 2016
  • NDIR $CO_2$ gas sensor was prototyped with ASIC implemented thermopile sensor which included temperature sensor and White-Cell structure in this paper. The temperature dependency of dual infrared sensors ($CO_2$ and reference IR sensors) has been characterized and their output voltage ratios according to the temperature and gas concentration were presented in this paper for achieving temperature compensation algorithm. The initial output voltages of NDIR $CO_2$ gas and reference IR sensors showed $3^{rd}$ order polynomial and linear output voltages according to the variation of ambient temperatures from 253 K to 333 K, respectively. The output voltages of temperature sensor presented a linear dependency according to the ambient temperature and could be described with V(T) = -3.0069+0.0145T(V). The characteristics of output voltage ratios could be modeled with five parameters which are dependent upon the ambient temperatures and gas concentration. The estimated $CO_2$ concentrations showed relatively high error below 300 ppm (maximum 572 % at 7 ppm $CO_2$ concentration), however, as the concentration increased from 500 ppm to 2,000 ppm, the overall estimated errors of $CO_2$ concentrations were less than ${\pm}10%$ in this research.