A novel microwave-based approach for monitoring the state of aftertreatment systems such as diesel particulate filters (DPFs), three-way catalytic converters (TWCs), and selective catalytic reduction (SCR) catalysts is proposed. The interior of the catalyst metal housing serves as a communication channel between two wireless communication nodes. It is shown that, depending on the transmission channel characteristics, the properties of the catalyst, such as the catalyst state, can be inferred.

The effect of stored ammonia on the complex dielectric permittivity of H-ZSM-5 zeolites with varying storage site density was observed between 200 and 300 °C under reaction conditions by microwave cavity perturbation. Polarization and dielectric losses were differently affected. The sensitivity of the polarization to stored ammonia is almost independent, the sensitivity of the dielectric losses strongly dependent on the storage site density. The results can be explained by proton hopping.

Hydrogen detection for purposes such as smart gas metering or fuel cell safety can be done by using a low-cost off-the-shelf thermopile IR radiation sensor and by driving it as a TCD (thermal conductivity detector). The MEMS thermopile sensor element is exposed to the measured gas environment. By applying an AC heating voltage to the thermopile structure and by measuring its DC output voltage, the hydrogen concentration of its gas environment can be measured with a resolution of up to 3.7ppm.

A highly sensitive spectral camera for the judgement of cartilage quality, grown in a bioreactor using the methods of tissue engineering, is being developed. It is optimized to detect weak fluorescence signals of different collagen types, elastin and glycosaminoglycans in the spectral region of 380nm to 500nm. Tests with a one- and a two-dimensional version of the system prove that collagen I and II can be detected and discriminated by their different spectral distributions.

We study the effect of HMDSO vapor on an SnO2-based gas sensor in temperature cycled operation (TCO). The poisoning can be quantified at early stages with a resolution of ±85 ppm*min using TCO. This approach provides a simple method for early detection of HMDSO poisoning. The stability of gas discrimination by linear discriminant analysis (LDA) can be improved using normalization, which in turn facilitates a more accurate determination of the poisoning state by hierarchical LDA discrimination.

Thimble-type lambda probes that are known for their robustness in harsh exhausts can also be used as an NOx sensor by applying the pulsed polarization technique. This study evaluates in detail the influence of temperature on the NO sensitivity, so that an optimum operating point can be derived. Stepwise NO concentration changes between 0 and 12.5 ppm in synthetic exhausts demonstrate the high potential of this concept.