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.
We present a novel path-integral method for the determination of time-dependent and time-averaged reaction rates in multidimensional, periodically driven escape problems at weak thermal noise. The so obtained general expressions are evaluated explicitly for the situation of a sinusoidally driven, damped particle with inertia moving in a metastable, piecewise parabolic potential. A comparison with data from Monte-Carlo simulations yields a very good agreement with analytic results over a wide parameter range.