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Functional Materials for Gas Sensors

Title data

Moos, Ralf:
Functional Materials for Gas Sensors.
2005
Event: International Materials Forum 2005 , 01.08.-02.08.2005 , Bayreuth, Deutschland.
(Conference item: Conference , Other Presentation type)

Abstract in another language

Gas sensors play an important role in daily life. Mostly they work in the background and are not noticed directly by the user. They may warn people against poisonous or hazardous components in the air. In the automotive exhaust gas, they measure the air-to-fuel ratio (lambda). This contribution gives an overview on the materials and principles that are utilized for gas sensing. The focus is on inorganic materials: mainly tin oxide for environmental applications (SnO2) and yttria stabilized zirconia (YSZ) for automotive applications. Both materials dominate the market. Environmental Applications Many types of sensors have been studied for the detection of chemical species in the gas phase. Besides optical sensors based on color change or fluoresence, surface acoustic wave (SAW) devices, electrochemical devices, field effect transistors (FET), or metal-insulatorsemiconductor (MIS) diode devices, resistive type sensors based on semiconducting ceramic oxides are of particular interest due to their low system cost. After a short introduction in the basic principles of n-type conducting SnO2 sensors, some applications are presented. It is shown that during the past years the main progress was not the optimization of the material, but the development of sensor systems that include smaller and less power consuming transducers. Strategies to enhance the selectivity are presented as well. Automotive Exhaust Gas Applications Nowadays, ceramic exhaust gas sensors are installed in quantities of millions in automotive exhaust gas systems. Almost any automobile being powered by a gasoline combustion engine is equipped with at least one zirconia exhaust gas oxygen sensor (lambda probe) for lambda-detection. Two sensing principles have been serialized: potentiometric and amperometric sensors. In the past years, a leap in manufacturing technology occurred from classical ceramic technology to planar tape and thick-film technology. The advent of novel combustion concepts like lean-burn operating gasoline direct injection required novel exhaust gas aftertreatment concepts. It pushed the development of the NOx sensor, which is manufactured in the same planar technology as amperometric lambda sensors. It is shown how development of exhaust gas sensors has always to be considered in interaction with exhaust gas aftertreatment systems. This elucidates why novel sensors have gained in importance just recently when stricter emission regulations were announced, meaning that time is ripe for novel exhaust gas aftertreatment concepts. Appropriate sensors - ammonia sensors, hydrocarbon sensors, and particulate matter sensors - are still in the R&D state. Several possible sensor principles are discussed. Besides ion-conducting YSZ, electrically insulating alumina is sometimes used for substrate purposes. Novel functional materials in the R&D state are strontium-iron titanate for temperature independent resistive oxygen sensing and zeolites for selective detection of specific gases like hydrocarbons or ammonia.

Further data

Item Type: Conference item (Other)
Refereed: Yes
Institutions of the University: Faculties > Faculty of Engineering Science
Faculties > Faculty of Engineering Science > Chair Functional Materials > Chair Functional Materials - Univ.-Prof. Dr.-Ing. Ralf Moos
Faculties
Faculties > Faculty of Engineering Science > Chair Functional Materials
Profile Fields > Advanced Fields > Advanced Materials
Research Institutions > Research Centres > Bayreuth Center for Material Science and Engineering - BayMAT
Profile Fields
Profile Fields > Advanced Fields
Research Institutions
Research Institutions > Research Centres
Result of work at the UBT: Yes
DDC Subjects: 600 Technology, medicine, applied sciences > 620 Engineering
Date Deposited: 16 Jun 2015 08:47
Last Modified: 05 Apr 2016 07:10
URI: https://eref.uni-bayreuth.de/id/eprint/14997