Solid State Gas Sensors: State of the Art and Future Activities

Journal of The Electrochemical Society, 1992

During the past three decades, gas sensors based either on the surface characteristics or the bulk electrolytic properties of ceramics, have been the subject of extensive research and development. The application of these sensors range from air-to-fuel ratio control in combustion processes such as in automotive engines and industrial furnaces to the detection of leakage of inflammable and toxic gases in domestic and industrial environments. While the solid-state physical sensors, measuring pressure, temperature, and other physical parameters have been commercially successful, less success has been achieved by their chemical analogs, to measure moderate to very low concentrations of gases of importance. These gases include: 02, H2, CO, CO2, NOx, SO=, propane, methane, ethanol, and so on. The semiconductor-based chemical sensors owe their popularity to their small size, simple operation, high sensitivity, and relatively simple associated electronics. However, most of them still suffer from nonselectivity. They also have poor shelf-life and are relatively less stable at higher temperatures. The sensing characteristics and performance of some of the solid-state gas sensors are reviewed in this paper, together with their sensing mechanism, which still is a gray area and has not been fully understood.

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Inorganic Materials, 2000

The major problems in the development of inorganic gas-sensor materials are discussed. The general principle of semiconductor gas sensors is considered, and the band-structure parameters sensitive to the gas-phase composition are determined. Ways of improving sensor selectivity are examined. The composition, microstructure, and gas sensitivity of nanocrystalline SnO 2 and ZnO are investigated. The dopant content and grain size of Ni-doped SnO 2 are optimized for H2S detection. The prospects of employing systems of two or more nanocrystalline oxides (nanocomposites) for gas detection are discussed.

Sensors (Basel, Switzerland), 2009

This status report overviews activities of the German gas sensor research community. It highlights recent progress in the field of potentiometric, amperometric, conductometric, impedimetric, and field effect-based gas sensors. It is shown that besides step-by-step improvements of conventional principles, e.g. by the application of novel materials, novel principles turned out to enable new markets. In the field of mixed potential gas sensors, novel materials allow for selective detection of combustion exhaust components. The same goal can be reached by using zeolites for impedimetric gas sensors. Operando spectroscopy is a powerful tool to learn about the mechanisms in n-type and in p-type conductometric sensors and to design knowledge-based improved sensor devices. Novel deposition methods are applied to gain direct access to the material morphology as well as to obtain dense thick metal oxide films without high temperature steps. Since conductometric and impedimetric sensors have t...

Sensors and Actuators B: Chemical, 2009

Two recent topics important for advancing gas sensor technology are introduced. Semiconductor gas sensors have been developed so far on empirical bases but now a fundamental theory has been made available for further developments. The theory reveals the roles of physical properties of semiconductors and chemical properties of gases in the receptor function. MEMS techniques have been applied to fabrication of micro-platforms for use in gas sensors. The micro-platforms appear to provide gas sensors with new innovative function.

International Journal of Recent Trends in Engineering and Research, 2018

This paper reviews the developments in existing gas sensing technologies through descriptions, evaluation and comparison. Here, detailed introduction to sensing methods and classification of sensing technologies is specified, based on the deviation of electrical and other properties are discussed. Sensing technology has been extensively investigated and utilized for gas detection. Researchers have been working on different scenarios with enhanced gas sensor calibration, due to the different applicability and inherent limitations of different gas sensing technologies. Gas sensor technology is advancing with the fast improvement of material science and semiconductor technology. This trend may be continuing in the coming days. In the semiconductor gas sensor regime "More than Moore" principle will be applicable as well. In this article, different gas sensors are evaluated and reviewed, in terms of their ability to operate at low-power, small-size, and relatively lowcost, by means of ambient conditions.

Sensors

This paper presents an overview of semiconductor materials used in gas sensors, their technology, design, and application. Semiconductor materials include metal oxides, conducting polymers, carbon nanotubes, and 2D materials. Metal oxides are most often the first choice due to their ease of fabrication, low cost, high sensitivity, and stability. Some of their disadvantages are low selectivity and high operating temperature. Conducting polymers have the advantage of a low operating temperature and can detect many organic vapors. They are flexible but affected by humidity. Carbon nanotubes are chemically and mechanically stable and are sensitive towards NO and NH3, but need dopants or modifications to sense other gases. Graphene, transition metal chalcogenides, boron nitride, transition metal carbides/nitrides, metal organic frameworks, and metal oxide nanosheets as 2D materials represent gas-sensing materials of the future, especially in medical devices, such as breath sensing. This ...

Sensors (Basel, Switzerland), 2012

Sensing technology has been widely investigated and utilized for gas detection. Due to the different applicability and inherent limitations of different gas sensing technologies, researchers have been working on different scenarios with enhanced gas sensor calibration. This paper reviews the descriptions, evaluation, comparison and recent developments in existing gas sensing technologies. A classification of sensing technologies is given, based on the variation of electrical and other properties. Detailed introduction to sensing methods based on electrical variation is discussed through further classification according to sensing materials, including metal oxide semiconductors, polymers, carbon nanotubes, and moisture absorbing materials. Methods based on other kinds of variations such as optical, calorimetric, acoustic and gas-chromatographic, are presented in a general way. Several suggestions related to future development are also discussed. Furthermore, this paper focuses on sen...

Ionics, 2007

Gas sensors has been currently in great demand because of serious concern over environmental pollution and public health considerations resulting from tremendous growth of industrialisation. Concurrently, there have been continuous efforts to obtain sensors with improved performance. The performance of any solid-state electrochemical gas sensor has been always rated on its response time, thermodynamic stability, operating temperature, gas sensing ability, sensitivity and gas concentration range, which is to be sensed. This article reviews the factors contributing towards a gradual development of electrochemical solidstate gas sensors in terms of a continuous tailoring of its two basic components, i.e. solid electrolyte and reference electrode.

Lalauze/Chemical Sensors and Biosensors, 2012