Anita Lloyd Spetz, Zhafira Darmastuti, Christian Bur, Joni Huotari, Robert Bjorklund, Niclas Lindqvist, Jyrki Lappalainen, Heli Jantunen, Andreas Schütze, Mike Andersson
Focusing on environment and health aspects, the importance of monitoring and controlling dangerous gases and particulate matter increases. For this purpose we present a new version of silicon carbide based gas sensors with improved properties and suitable for high temperature and harsh environments such as power plants or car exhausts. Development of sulfur dioxide sensors for a power plant application is described as well as sensors for detection of ammonia in connection with the SCR process where urea is converted to ammonia, which reduces nitric oxide components in the exhausts. We also describe progress on nanoparticle detection, especially related to detection of the content of adsorbed particles through heating and detection of emitted molecules by a sensor array. Some results are also presented from impedance spectroscopy for detection of the concentration of nanoparticles but with the potential to reveal more details about the particles such as shape and kind of particles.
A Silicon Carbide based enhancement type field effect transistor with porous films of Iridium and Platinum as gate
metallization has been investigated as a total NOx sensor operated in a temperature cycling mode. This operating mode is
quite new for gas sensors based on the field effect but promising results have been reported earlier. Based on static
investigations we have developed a suitable T-cycle for NOx detection in a mixture of typical exhaust gases (CO, C2H4,
and NH3). Significant features describing the shape of the sensor response have been extracted allowing determination of
NOx concentrations in gas mixtures. Multivariate statistics (e.g. Linear Discriminant Analysis) have been used to
evaluate the multidimensional data. With this kind of advanced signal processing the influence of sensor drift and cross
sensitivity to ambient gases can effectively be reduced. Thereby, we were able to detect NOx and furthermore determine
different concentrations of NOx even in mixtures with typical exhaust gases. It can be concluded that the performance of
field effect gas sensors for NOx determination can be enhanced considerably.
Wide bandgap materials like SiC, ZnO, AlN form a strong platform as transducers for biosensors
realized as e.g. ISFET (ion selective field effect transistor) devices or resonators. We have taken two
main steps towards a multifunctional biosensor transducer. First we have successfully functionalized
ZnO and SiC surfaces with e.g. APTES. For example ZnO is interesting since it may be
functionalized with biomolecules without any oxidation of the surface and several sensing principles
are possible. Second, ISFET devises with a porous metal gate as a semi-reference electrode are being
developed. Nitric oxide, NO, is a gas which participates in the metabolism. Resistivity changes in Ga
doped ZnO was demonstrated as promising for NO sensing also in humid atmosphere, in order to
simulate breath.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.