• Title/Summary/Keyword: Non-dispersive infrared

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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.

Non-dispersive infrared carbon dioxide sensor with an externally exposed optical cavity (광 도파관이 외부로 노출된 구조를 가지는 비분산적외선 이산화탄소 센서)

  • Jung, Dong Geon;Lee, Junyeop;Do, Nam Gon;Jung, Daewoong
    • Journal of Sensor Science and Technology
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    • v.30 no.6
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    • pp.456-460
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    • 2021
  • In this study, a Non-Dispersive Infrared (NDIR) Carbon Dioxide (CO2) sensor with an externally exposed optical cavity is proposed for improving sensitivity. NDIR CO2 sensors with high performance must use a lamp-type infrared (IR) source with a strong IR intensity. However, a lamp-type IR source generates high thermal energy that induces thermal noise, interfering with the accuracy of the CO2 concentration measure. To solve this problem, the optical cavity of the NDIR CO2 sensor is exposed to quickly dissipate heat. As a result, the proposed NDIR CO2 sensor has a shorter warm-up time and a higher sensitivity compared to the conventional NDIR CO2 sensor.

An Optical Cavity Design for an Infrared Gas Detector Using an Off-axis Parabolic Mirror

  • Jeong, You-Jin;Kang, Dong-Hwa;Seo, Jae-Yeong;Jo, Ye-Ji;Seo, Jin-Hee;Choi, Hwan-Young;Jung, Mee-Suk
    • Current Optics and Photonics
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    • v.3 no.5
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    • pp.374-381
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    • 2019
  • This study examined a method for designing the optical cavity of a non-dispersive infrared gas detector. The infrared gas detector requires an optical cavity design to lengthen the ray path. However, the optical cavity with multiple reflecting surfaces has off-axis aberration due to the characteristics of the reflecting optical system. The rays were parallelized by using the off-axis parabolic mirror to easily increase the ray path and eliminate off-axis aberration so that the rays are admitted to the effective area of the infrared detector uniformly. A prototype of an infrared gas detector was produced with the designed optical cavity to confirm the performance.

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.

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.

Sensing characteristics of a non-dispersive infrared CO2 sensor using a Fabry-Perot filter based on distributed Bragg reflector (분산 반사경 기반 패브리-페로 필터를 이용한 비분산적외선 CO2 센서의 감지 특성)

  • Do, Nam Gon;Lee, Junyeop;Jung, Dong Geon;Kong, Seong Ho;Jung, Daewoong
    • Journal of Sensor Science and Technology
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    • v.30 no.6
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    • pp.446-450
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    • 2021
  • Non-dispersive infrared (NDIR) gas sensors typically use an optical filter that transmits a discriminating 4.26 ㎛ wavelength band to measure carbon dioxide (CO2), as CO2 absorbs 4.26 ㎛ infrared. The filter performance depends on the transmittance and full width at half maximum (FWHM). This paper presents the fabrication, sensitivity, and selectivity characteristics of a distributed Bragg reflector (DBR)-based Fabry-Perot filter with a simple structure for CO2 detection. Each Ge and SiO2 films were prepared using the RF magnetron sputtering technique. The transmittance characteristics were measured using Fourier-transform infrared spectroscopy (FT-IR). The fabricated filter had a peak transmittance of 59.1% at 4.26 ㎛ and a FWHM of 158 nm. In addition, sensitivity and selectivity experiments were conducted by mounting the sapphire substrate and the fabricated filter on an NDIR CO2 sensor measurement system. When measuring the sensitivity, the concentration of CO2 was observed in the range of 0-10000 ppm, and the selectivity was measured for environmental gases of 1000 ppm. The fabricated filter showed lower sensitivity to CO2 but showed higher selectivity with other gases.

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 ${\pm}10%$.

EVALUATION OF NON-INVASIVE BLOOD GLUCOSE MEASUREMENT USING THREE TYPES OF NEAR INFRARED SPECTROMETER

  • Baek, Ju-Hyun;Kang, Na-Roo;Woo, Young-Ah;Kim, Hyo-Jin
    • Proceedings of the PSK Conference
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    • 2003.04a
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    • pp.289.1-289.1
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    • 2003
  • Three types of near infrared spectrometer, a photo diode array type, a dispersive type and a FT type, were evaluated and compared the systematic difference in blood glucose measurement. The fundamental study was performed by adding glucose to buffer solution and bovine blood as the preceding study of non-invasive blood glucose. Spectra were collected using a 1.0 mm optical pathlength quartz cell by transmittance method. (omitted)

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Design and performance study of fabry-perot filter based on DBR for a non-dispersive infrared carbon dioxide sensor (비분산적외선 CO2 센서를 위한 DBR기반의 패브리 페로-필터 설계 및 성능 연구)

  • Do, Nam Gon;Lee, Junyeop;Jung, Dong Geon;Kong, Seong Ho;Jung, Daewoong
    • Journal of Sensor Science and Technology
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    • v.30 no.4
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    • pp.250-254
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    • 2021
  • A highly sensitive and selective non-dispersive infrared (NDIR) carbon dioxide gas sensor requires achieving high transmittance and narrow full width at half maximum (FWHM), which depends on the interface of the optical filter for precise measurement of carbon dioxide concentration. This paper presents the design, simulation, and fabrication of a Fabry-Perot filter based on a distributed Bragg reflector (DBR) for a low-cost NDIR carbon dioxide sensor. The Fabry-Perot filter consists of upper and lower DBR pairs, which comprise multilayered stacks of alternating high- and low-index thin films, and a cavity layer for the resonance of incident light. As the number of DBR pairs inside the reflector increases, the FWHM of the transmitted light becomes narrower, but the transmittance of light decreases substantially. Therefore, it is essential to analyze the relationship between the FWHM and transmittance according to the number of DBR pairs. The DBR is made of silicon and silicon dioxide by RF magnetron sputtering on a glass wafer. After the optimal conditions based on simulation results were realized, the DBR exhibited a light transmittance of 38.5% at 4.26 ㎛ and an FWHM of 158 nm. The improved results substantiate the advantages of the low-cost and minimized process compared to expensive commercial filters.