• Title, Summary, Keyword: Metal Oxide sensors

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Conducting Metal Oxide Interdigitated Electrodes for Semiconducting Metal Oxide Gas Sensors

  • Shim, Young-Seok;Moon, Hi-Gyu;Kim, Do-Hong;Jang, Ho-Won;Yoon, Young-Soo;Yoon, Soek-Jin
    • Proceedings of the Korean Vacuum Society Conference
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    • pp.65-65
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    • 2011
  • We report the application of conducting metal oxide electrodes for semiconducting metal oxide gas sensors. Pt interdigitated electrodes have been commonly used for metal oxide gas sensor because of the low resistivity, excellent thermal and chemical stability of Pt. However, the high cost of Pt is an obstacle for the wide use of metal oxide gas sensors compared with its counterpart electrochemical gas sensors. Meanwhile, relatively low-cost conducting metal oxides are widely being used for light-emitting diodes, flat panel displays, solar cell and etc. In this work, we have fabricated $WO_3$ and $SnO_2$ thin film gas sensors using interdigitated electrodes of conducting metal oxides. Thin film gas sensors based on conducting metal oxides exhibited superior gas sensing properties than those using Pt interdigitated electrodes. The result was attributed to the low contact resistance between the conducting metal oxide and the sensing material. Consequently, we demonstrated the feasibility of conducting metal oxide interdigitated electrodes for novel gas sensors.

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Fabrication of 1D Metal Oxide Nanostructures Using Glancing Angle Deposition for High Performance Gas Sensors

  • Suh, Jun Min;Jang, Ho Won
    • Journal of Sensor Science and Technology
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    • v.26 no.4
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    • pp.228-234
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    • 2017
  • Gas sensors based on metal-oxide-semiconductors are predominantly used in numerous applications including monitoring indoor air quality and detecting harmful substances such as volatile organic compounds. Nanostructures, e.g., nanoparticles, nanotubes, nanodomes, or nanofibers, have been widely utilized to improve the gas sensing properties of metal-oxide-semiconductors by increasing the effective surface area participating in the surface reaction with target gas molecules. Recently, 1-dimensional (1D) metal oxide nanostructures fabricated using glancing angle deposition (GAD) method with e-beam evaporation have been widely employed to increase the surface-to-volume ratio significantly with large-area uniformity and reproducibility, leading to promising gas sensing properties. Herein, we provide a brief overview of 1D metal oxide nanostructures fabricated using GAD and their gas sensing properties in terms of fabrication methods, morphologies, and additives. Moreover, the gas sensing mechanisms and perspectives are presented.

Recent Trends of Light-enhanced Metal Oxide Gas Sensors: Review

  • Cho, Minkyu;Park, Inkyu
    • Journal of Sensor Science and Technology
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    • v.25 no.2
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    • pp.103-109
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    • 2016
  • Recent light-enhanced metal oxide gas sensors are reviewed in this article. The basic mechanisms of a light-enhanced metal oxide gas sensor are discussed. Many literatures reveal that the standalone sensitivity and the response/recovery time enhancements enabled by the exposing light are not as high as the performance enhancement provided by external heating. Therefore, both optimal amount of external heating and exposed light intensity are necessary to increase the performance of these light-enhanced gas sensors. The development of highly light sensitive materials and structures is important to lower the overall power consumptions of the sensors.

Recent Developments in Metal Oxide Gas Sensors for Breath Analysis (산화물 반도체를 이용한 최신 호기센서 기술 동향)

  • Yoon, Ji-Wook;Lee, Jong-Heun
    • Ceramist
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    • v.22 no.1
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    • pp.70-81
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    • 2019
  • Breath analysis is rapidly evolving as a non-invasive disease recognition and diagnosis method. Metal oxide gas sensors are one of the most ideal platforms for realizing portable, hand-held breath analysis devices in the near future. This paper reviewed the recent developments in metal oxide gas sensors detecting exhaled biomarker gases such as nitric oxides, acetone, ammonia, hydrogen sulfide, and hydrocarbons. Emphasis was placed on strategies to tailor sensing materials/films capable of highly selective and sensitive detection of biomarker gases with negligible cross-response to ethanol, the major interfering breath gas. Specific examples were given to highlight the validity of the strategies, which include optimization of sensing temperature, doping additives, utilizing acid-base interaction, loading catalysts, and controlling gas reforming reaction. In addition, we briefly discussed the design and optimization method of gas sensor arrays for implementing the simultaneous assessment of multiple diseases. Breath analysis using high-performance metal oxide gas sensors/arrays will open new roads for point-of-care diagnosis of diseases such as asthma, diabetes, kidney dysfunction, halitosis, and lung cancer.

Synthesis of Nanoporous Metal Oxide Films Using Anodic Oxidation and Their Gas Sensing Properties

  • Suh, Jun Min;Kim, Do Hong;Jang, Ho Won
    • Journal of Sensor Science and Technology
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    • v.27 no.1
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    • pp.13-20
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    • 2018
  • Gas sensors based on metal oxide semiconductors are used in numerous applications including monitoring indoor air quality and detecting harmful substances like volatile organic compounds. Nanostructures, for example, nanoparticles, nanotubes, nanodomes, and nanofibers have been widely utilized to improve gas sensing properties of metal oxide semiconductors, and this increases the effective surface area, resulting in participation of more target gas molecules in the surface reaction. In the recent times, 1-dimensional (1D) metal oxide nanostructures fabricated using anodic oxidation have attracted great attention due to their high surface-to-volume ratio with large-area uniformity, reproducibility, and capability of synthesis under ambient air and pressure, leading to cost-effectiveness. Here, we provide a brief overview of 1D metal oxide nanostructures fabricated by anodic oxidation and their gas sensing properties. In addition, recent progress on thin film-based anodic oxidation for application in gas sensors is introduced.

Effect of Noble Metals on Hydrogen Sensing Properties of Metal Oxide-based Gas Sensors

  • Mirzaei, Ali;Bang, Jae Hoon;Kim, Sang Sub;Kim, Hyoun Woo
    • Journal of Sensor Science and Technology
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    • v.29 no.6
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    • pp.365-368
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    • 2020
  • As a green and abundant source of energy, H2 has attracted the attention of researchers for use in different applications. Nevertheless, it is highly flammable, and because of its significantly small size, extreme attention is needed to detect its leakage. In this review, we discuss different effects of noble metals on the H2 gas response and performance of metal oxide-based gas sensors. In this regard, we discuss the effects of noble metals, in combination with metal oxides, on H2 gas detection. The catalytic activity towards H2 gas and the formation of heterojunctions with metal oxides are the main contributions of noble metals to the sensing improvement of H2 gas sensors. Furthermore, in the special case of Pd and somewhat Pt, the formation of PdHx and PtHx also affects the H2 sensing performance. This review paper provides useful information for researchers working in the field of H2 gas detection.

Design of Metal Oxide Hollow Structures Using Soft-templating Method for High-Performance Gas Sensors

  • Shim, Young-Seok;Jang, Ho Won
    • Journal of Sensor Science and Technology
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    • v.25 no.3
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    • pp.178-183
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    • 2016
  • Semiconductor gas sensors based on metal oxide are widely used in a number of applications, from health and safety to energy efficiency and emission control. Nanomaterials including nanowires, nanorods, and nanoparticles have dominated the research focus in this field owing to their large number of surface sites that facilitate surface reactions. Recently, metal oxide hollow structures using soft templates have been developed owing to their high sensing properties with large-area uniformity. Here, we provide a brief overview of metal oxide hollow structures and their gas-sensing properties from the aspects of template size, morphology, and additives. In addition, a gas-sensing mechanism and perspectives are presented.

Enhancing Gas Response Characteristics of Mixed Metal Oxide Gas Sensors

  • Balamurugan, Chandran;Song, Sun-Ju;Kim, Ho-Sung
    • Journal of the Korean Ceramic Society
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    • v.55 no.1
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    • pp.1-20
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    • 2018
  • Semiconducting nanomaterials have attracted considerable interest in recent years due to their high sensitivity, selectivity, and fast response time. In addition, for portable applications, they have low power consumption, lightweight, simple in operation, a low maintenance cost. Furthermore, it is easy to manufacture microelectronic sensor structures with metallic oxide sensitive thin layers. The use of semiconducting metal oxides to develop highly sensitive chemiresistive sensing systems remains an important scientific challenge in the field of gas sensing. According to the sensing mechanisms of gas sensors, the overall sensor conductance is determined by surface reactions and the charge transfer processes between the adsorbed species and the sensing material. The primary goal of the present study is to explore the possibility of using semiconducting mixed metal oxide nanostructure as a potential sensor material for selective gases.

Position-Selective Metal Oxide Nanostructures using Atomic Thin Carbon Layer for Hydrogen Gas Sensors

  • Yu, Hak Ki
    • Journal of Sensor Science and Technology
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    • v.29 no.6
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    • pp.369-373
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    • 2020
  • A hydrogen sensor was fabricated by utilizing a bundle of metal oxide nanostructures whose growth positions were selectively controlled by utilizing graphene, which is a carbon of atomic-unit thickness. To verify the reducing ability of graphene, it was confirmed that the multi-composition metal oxide V2O5 was converted into VO2 on the graphene surface. Because of the role of graphene as a reducing catalyst, it was confirmed that ZnO and MoO3 nanostructures were grown at high density only on the graphene surface. The fabricated gas sensor showed excellent sensitivity.

Design of a Smart Gas Sensor System for Room Air-Cleaner of Automobile (Thick-Film Metal Oxide Semiconductor Gas Sensor)

  • Kim, Jung-Yoon;Shin, Tae-Zi;Yang, Myung-Kook
    • Journal of Electrical Engineering and Technology
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    • v.2 no.3
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    • pp.408-412
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    • 2007
  • It is almost impossible to secure the reproductibility and stability of a commercial Thick-Film Metal Oxide Semiconductor Gas Sensor since it is very difficult to keep the consistency of the manufacturing environment. Thus it is widely known that the general Semiconductor-Oxide Gas Sensors are not appropriate for precise measurement systems. In this paper, the output characteristic analyzer of the various Thick-Film Metal Oxide Semiconductor Gas Sensors that are used to recognize the air quality within an automobile are proposed and examined. The analyzed output characters in a normal air chamber are grouped by sensor ranks and used to fill out the characteristic table of the Thick-Film Metal Oxide Semiconductor Gas Sensors. The characteristic table is used to determine the rank of the sensor that is equipped in the current air cleaner system of an automobile. The proposed air control system can also adapt the on-demand operation that recognizes the history of the passenger's manual-control.