A semiconductor gas sensor array combined with a routine for pattern recognition - a so-called electronic nose - for the detection of gas emissions from the leather used in car compartments is described. The gas sensors are 10 metal oxide semiconductor field effect transistors (MOSFETs) with gates of thin, catalytic metals, and five semiconducting metal oxide sensors. The sensor array data are processed by multivariate means using principal component analysis (PCA) and are shown to give similar and add additional information compared to gas chromatography-mass spectrometry (GC- MS) and a human sensory panel. The total volatile organic compound concentration as measured by GC did not differ between good and bad samples and could therefore not be used as a quality control tool, whilst the electronic nose together with pattern recognition could readily discover the deviating samples with unusual emitting gases. This set-up could be useful in on-line quality monitoring systems to detect anomalies in incoming car interior trim materials.

A combination of charcoal and particle filters has previously been shown to reduce effectively the smell of diesel exhaust. In this paper it is shown that the smell of diesel exhaust can successfully be predicted by the concentration of total volatile organic compounds and the concentration of certain carbonyl compounds. Projection to latent structures was utilised for model building. An electronic nose consisting of MOSFET and MOS sensors could less successfully predict the smell, but identified the same filter combination as being most efficient. The car cabin air during urban driving was also monitored, both by the means of MOSFET sensors and by chemiluminescence. The pollution level inside the car is shown to be elevated by about 30% compared to outside the car. A combination filter together with an air inlet sensor switch is shown to reduce the NOx levels inside the car by 30% compared to outside, with the ability to significantly decrease the peak levels. Copyright © 2002 S. Karger AG, Basel.