羟氨苄青霉素引起大疱性类天疱疮样疹

Conductometric semiconducting metal oxide gas sensors have been widely used and investigated in the detection of gases. Investigations have indicated that the gas sensing process is strongly related to surface reactions, so one of the important parameters of gas sensors, the sensitivity of the metal oxide based materials, will change with the factors influencing the surface reactions, such as chemical components, surface-modification and microstructures of sensing layers, temperature and humidity. In this brief review, attention will be focused on changes of sensitivity of conductometric semiconducting metal oxide gas sensors due to the five factors mentioned above.

Metal oxide gas sensors: Sensitivity and influencing factors

The analysis of various parameters of metal oxides and the search of criteria, which could be used during material selection for solid-state gas sensor applications, were the main objectives of this review. For these purposes the correlation between electro-physical (band gap, electroconductivity, type of conductivity, oxygen diffusion), thermodynamic, surface, electronic, structural properties, catalytic activity and gas-sensing characteristics of metal oxides designed for solid-state sensors was established. It has been discussed the role of metal oxide manufacturability, chemical activity, and parameter's stability in sensing material choice as well.

Metal oxides for solid-state gas sensors: What determines our choice?

Hierarchical and hollow oxide nanostructures are very promising gas sensor materials due to their high surface area and well-aligned nanoporous structures with a less agglomerated configurations. Various synthetic strategies to prepare such hierarchical and hollow structures for gas sensor applications are reviewed and the principle parameters and mechanisms to enhance the gas sensing characteristics are investigated. The literature data clearly show that hierarchical and hollow nanostructures increase both the gas response and response speed simultaneously and substantially. This can be explained by the rapid and effective gas diffusion toward the entire sensing surfaces via the porous structures. Finally, the impact of highly sensitive and fast responding gas sensors using hierarchical and hollow nanostructures on future research directions is discussed.

Gas sensors using hierarchical and hollow oxide nanostructures: Overview

Sensor technology is one of the most important key technologies of the future with a constantly increasing number of applications, both in the industrial and in the private sectors. More and more gas sensors are used for the control of technical processes, in environment monitoring, healthcare, and automobiles. Consequently, the development of fast and sensitive gas sensors with small cross sensitivity is the subject of intense research, propelled by strategies based on nanoscience and -technology. Established systems can be improved and novel sensor concepts based on bottom-up approaches show that the sensor properties can be controlled by molecular design. This Review highlights the recent developments and reflects the impact of nanoscience on sensor technology.

Metal and Metal Oxide Nanoparticles in Chemiresistors: Does the Nanoscale Matter?

The influence of film structure on In2O3 gas response

Structural stability of indium oxide films deposited by spray pyrolysis during thermal annealing

Influence of surface Pd doping on gas sensing characteristics of SnO2 thin films deposited by spray pirolysis

The correlation between technological modes of In2O3 film deposition by spray pyrolysis and gas response to ozone is discussed in this report. In2O3 films were deposited from InCl 3–water solution (Tpyr = 300–550 ◦ C). It is shown that grain size, porosity, and film stoichiometry are the main factors controlling gas sensing characteristics of In 2O3 films. Porous films with minimal grain sizes and maximal deviation from stoichiometry have both maximal gas response to ozone, and minimal response time. For films with optimal structure, the gas response to ozone (Rozone/Rair) reaches a value of ∼10 3 to 10 4 . Recommendations are made for optimizing the method of In2O3 film deposition to achieve optimal gas response to ozone.

In2O3 films deposited by spray pyrolysis as a material for ozone gas sensors

The gas-sensing properties of SnO2-based thin films designed for ozone detection are discussed in this paper. The influence of film characteristics on sensor performance is analyzed. SnO2 films with thickness 30–200 nm were deposited by spray pyrolysis. The SnO2 films have a response to ozone that is quantitative and rapid and sufficient for use in ozone control and monitoring applications. Sensor performance is compared with similarly prepared sensors fabricated from In2O3- and WO3-based films. The mechanism of the processes controlling the sensor response characteristics is proposed. The data support our conclusion that the reaction with ozone using the SnO2-film sensors is limited by the adsorption/desorption processes.

M. Ivanov

Papers

The influence of film structure on In2O3 gas response

Structural stability of indium oxide films deposited by spray pyrolysis during thermal annealing

Influence of surface Pd doping on gas sensing characteristics of SnO2 thin films deposited by spray pirolysis

In2O3 films deposited by spray pyrolysis as a material for ozone gas sensors

Ozone sensors on the base of SnO2 films deposited by spray pyrolysis