• Title/Summary/Keyword: gas sensing

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Fabrication and ethanol gas sensing characteristics of the thick film ethanol gas sensors (후막형 에탄올 가스 감지소자의 제조 및 특성)

  • Choi, Dong-Han
    • Journal of Sensor Science and Technology
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    • v.16 no.6
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    • pp.428-433
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    • 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.

Semiconducting ZnO Nanofibers as Gas Sensors and Gas Response Improvement by $SnO_2$ Coating

  • Moon, Jae-Hyun;Park, Jin-Ah;Lee, Su-Jae;Zyung, Tae-Hyoung
    • ETRI Journal
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    • v.31 no.6
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    • pp.636-641
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    • 2009
  • ZnO nanofibers were electro-spun from a solution containing poly 4-vinyl phenol and Zn acetate dihydrate. The calcination process of the ZnO/PVP composite nanofibers brought forth a random network of polycrystalline wurtzite ZnO nanofibers of 30 nm to 70 nm in diameter. The electrical properties of the ZnO nanofibers were governed by the grain boundaries. To investigate possible applications of the ZnO nanofibers, their CO and $NO_2$ gas sensing responses are demonstrated. In particular, the $SnO_2$-deposited ZnO nanofibers exhibit a remarkable gas sensing response to $NO_2$ gas as low as 400 ppb. Oxide nanofibers emerge as a new proposition for oxide-based gas sensors.

Hydrogen Sensing of Graphene-based Chemoresistive Gas Sensor Enabled by Surface Decoration

  • Eom, Tae Hoon;Kim, Taehoon;Jang, Ho Won
    • Journal of Sensor Science and Technology
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    • v.29 no.6
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    • pp.382-387
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    • 2020
  • Hydrogen (H2) is considered as a new clean energy resource for replacing petroleum because it produces only H2O after the combustion process. However, owing to its explosive nature, it is extremely important to detect H2 gas in the ambient atmosphere. This has triggered the development of H2 gas sensors. 2-dimensional (2D) graphene has emerged as one of the most promising candidates for chemical sensors in various industries. In particular, graphene exhibits outstanding potential in chemoresistive gas sensors for the detection of diverse harmful gases and the control of indoor air quality. Graphene-based chemoresistive gas sensors have attracted tremendous attention owing to their promising properties such as room temperature operation, effective gas adsorption, and high flexibility and transparency. Pristine graphene exhibits good sensitivity to NO2 gas at room temperature and relatively low sensitivity to H2 gas. Thus, research to control the selectivity of graphene gas sensors and improve the sensitivity to H2 gas has been performed. Noble metal decoration and metal oxide decoration on the surface of graphene are the most favored approaches for effectively controlling the selectivity of graphene gas sensors. Herein, we introduce several strategies that enhance the sensitivity of graphene gas sensors to H2 gas.

MEMS-Based Micro Sensor Detecting the Nitrogen Oxide Gases (산화질소 검출용 마이크로 가스센서 제조공정)

  • Kim, Jung-Sik;Yoon, Jin-Ho;Kim, Bum-Joon
    • Korean Journal of Materials Research
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    • v.23 no.6
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    • pp.299-303
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    • 2013
  • In this study, a micro gas sensor for $NO_x$ was fabricated using a microelectromechanical system (MEMS) technology and sol-gel process. The membrane and micro heater of the sensor platform were fabricated by a standard MEMS and CMOS technology with minor changes. The sensing electrode and micro heater were designed to have a co-planar structure with a Pt thin film layer. The size of the gas sensor device was about $2mm{\times}2mm$. Indium oxide as a sensing material for the $NO_x$ gas was synthesized by a sol-gel process. The particle size of synthesized $In_2O_3$ was identified as about 50 nm by field emission scanning electron microscopy (FE-SEM). The maximum gas sensitivity of indium oxide, as measured in terms of the relative resistance ($R_s=R_{gas}/R_{air}$), occurred at $300^{\circ}C$ with a value of 8.0 at 1 ppm $NO_2$ gas. The response and recovery times were within 60 seconds and 2 min, respectively. The sensing properties of the $NO_2$ gas showed good linear behavior with an increase of gas concentration. This study confirms that a MEMS-based gas sensor is a potential candidate as an automobile gas sensor with many advantages: small dimension, high sensitivity, short response time and low power consumption.

Identification of Gas Mixture with the MEMS Sensor Arrays by a Pattern Recognition

  • Bum-Joon Kim;Jung-Sik Kim
    • Korean Journal of Materials Research
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    • v.34 no.5
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    • pp.235-241
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    • 2024
  • Gas identification techniques using pattern recognition methods were developed from four micro-electronic gas sensors for noxious gas mixture analysis. The target gases for the air quality monitoring inside vehicles were two exhaust gases, carbon monoxide (CO) and nitrogen oxides (NOx), and two odor gases, ammonia (NH3) and formaldehyde (HCHO). Four MEMS gas sensors with sensing materials of Pd-SnO2 for CO, In2O3 for NOX, Ru-WO3 for NH3, and hybridized SnO2-ZnO material for HCHO were fabricated. In six binary mixed gas systems with oxidizing and reducing gases, the gas sensing behaviors and the sensor responses of these methods were examined for the discrimination of gas species. The gas sensitivity data was extracted and their patterns were determined using principal component analysis (PCA) techniques. The PCA plot results showed good separation among the mixed gas systems, suggesting that the gas mixture tests for noxious gases and their mixtures could be well classified and discriminated changes.

UV Enhanced NO2 Sensing Properties of Pt Functionalized Ga2O3 Nanorods

  • An, Soyeon;Park, Sunghoon;Mun, Youngho;Lee, Chongmu
    • Bulletin of the Korean Chemical Society
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    • v.34 no.6
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    • pp.1632-1636
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    • 2013
  • $Ga_2O_3$ one-dimensional (1D) nanostructures were synthesized by using a thermal evaporation technique. The morphology, crystal structure, and sensing properties of the $Ga_2O_3$ nanostructures functionalized with Pt to $NO_2$ gas at room temperature under UV irradiation were examined. The diameters of the 1D nanostructures ranged from a few tens to a few hundreds of nanometers and the lengths ranged up to a few hundreds of micrometers. Pt nanoparticles with diameters of a few tens of nanometers were distributed around a $Ga_2O_3$ nanorod. The responses of the nanorods gas sensors fabricated from multiple networked $Ga_2O_3$ nanorods were improved 3-4 fold at $NO_2$ concentrations ranging from 1 to 5 ppm by Pt functionalization. The Pt-functionalized $Ga_2O_3$ nanorod gas sensors showed a remarkably enhanced response at room temperature under ultraviolet (UV) light illumination. In addition, the mechanisms via which the gas sensing properties of $Ga_2O_3$ nanorods are enhanced by Pt functionalization and UV irradiation are discussed.

Gas Sensing Technologies for Power System Diagnosis (전력기기 이상 진단을 위한 가스 센싱 기술 검토)

  • Lee Jae Duck;Ryoo Hee Suk;Choi Sang Bong;Nam Kee Young;Jeong Seong Hwan;Kim Dae Kyeong;Choi Don Soo
    • Proceedings of the KIEE Conference
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    • summer
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    • pp.622-624
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    • 2004
  • To reduce the effect of fault on power systems, like GIS and transformers, power system authorities are using various technologies to monitor and diagnose there facilities. Developing On-Line monitoring systems by using IT technology is main issue of nowadays for power system authorities. Among various monitoring and diagnosis technologies, gas sensing technologies can be most useful candidate because large power systems are using gas and oils for there insulation and analyzing density of gases that are included in the gas and oils for insulation purpose tell us what kind of reaction were arisen. In this paper, we describe on the gas sensing technology that are used for power systems monitoring and diagnosis.

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Characteristics of Thick Film Gas Sensors Using Nano ZnO:CNT (나노 ZnO:CNT를 이용한 후막 가스센서의 특성연구)

  • Yoon, So-Jin;Yu, Il
    • Korean Journal of Materials Research
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    • v.24 no.8
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    • pp.413-416
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    • 2014
  • The effects of an addition of CNT on the sensing properties of nano ZnO:CNT-based gas sensors were studied for $H_2S$ gas. The nano ZnO sensing materials were grown by a hydrothermal reaction method. The nano ZnO:CNT was prepared by ball-milling method. The weight range of the CNT addition on the ZnO surface was from 0 to 10%. The nano ZnO:CNT gas sensors were fabricated by a screen-printing method on alumina substrates. The structural and morphological properties of the ZnO:CNT sensing materials were investigated by XRD, EDS, and SEM. The XRD patterns revealed that nano ZnO:CNT powders with a wurtzite structure were grown with (1 0 0), (0 0 2), and (1 0 1) dominant peaks. The size of the ZnO was about 210 nm, as confirmed by SEM images. The sensitivity of the nano ZnO:CNT-based sensors was measured for 5 ppm of $H_2S$ gas at room temperature by comparing the resistance in air with that in target gases.

The CO sensing properties of thick film gas sensor using Co3O4 powders prepared by hydrothermal reaction method (수열합성법으로 제조된 Co3O4 분말을 사용한후막 가스센서의 CO 감지 특성)

  • Kim, Kwang-Hee;Kim, Jeong-Gyoo;Park, Ki-Cheol
    • Journal of Sensor Science and Technology
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    • v.19 no.5
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    • pp.385-390
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    • 2010
  • CO sensing thick film gas sensors using $Co_3O_4$ powders prepared by hydrothermal reaction method, were fabricated, and their structural, electrical and CO gas sensing properties were investigated. The specific surface area of the $Co_3O_4$ powders obtained from BET analysis was about 79.0 $m^2/g$. XRD and SEM results show that the thick films heat-treated at $500^{\circ}C$ for 30 min after screen printing had the preferred orientation of (311) direction and the crystalline size was calculated to 221 $\AA$. The maximum activation energy obtained from the temperature-resistance characteristics was 3.11 eV in the temperature range of $290^{\circ}C$ to $310^{\circ}C$. The sensitivity to 1,000 ppm CO was about 150 %. The specific surface area, crystalline size, and maximum activation energy were increased significantly and the sensitivity for CO gas was improved largely.

Thickness Dependence of GZO Gas Sensing Films Deposited on LTCC Substrates (LTCC 기판상에 증착한 GZO 가스 센싱 박막의 두께 의존 특성 연구)

  • Hwang, Hyun Suk
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.24 no.3
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    • pp.215-218
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    • 2011
  • A novel design of gas sensor using Ga-doped ZnO (GZO) thin films which are deposited on low temperature co-fired ceramic (LTCC) substrates is presented. The LTCC substrates with thickness of 400 ${\mu}m$ are fabricated by laminating 12 green tapes which consist of alumina and glass particle in an organic binder. The GZO thin films with different thickness are deposited on LTCC substrates, by RF magnetron sputtering method. The microstructure and sensing properties of GZO gas sensing films are analyzed as a function of the film thickness. The films are well crystallized in the hexagonal (wurzite) structure with increasing thickness. The maximum sensitivity of 3.49 is obtained at 100 nm film thickness and the fastest 90% response time of 27.2 sec is obtained at 50 nm film thickness for the operating temperature of $400^{\circ}C$ to the $NO_2$ gas.