On ‘Electronic Nose’ methodology

• Critical review of ‘electronic nose’ measurements.
• Fundamentals of a new terminology and methodology.
• Criteria for evidenced method developments.

Gas measurement systems used with a particular methodology are sometimes referred to as “Electronic noses”. Traditionally, these systems were based on unspecific gas sensors as detectors, but within the last years, the measurement philosophy has also been extended to fast gas chromatographs or mass spectrometers. The mere word ‘electronic nose’ is very seductive and has evoked the expectation of odor measurement capability of such systems. This was exacerbated by constitutive scientific publications that claimed the odor measurement capability of ‘electronic noses’ as a matter of course. Moreover, the biomimetic background of the electronic nose technology was assumed as justification to address odor and aroma measurement tasks directly. But although the wealth of publications report about seemingly successful applications, the lack of practical industrial applications advises caution. Authors often tend to report selected results obtained under ideal conditions. Therefore, it is difficult or even impossible to find electronic nose systems in real routine use outside of scientific laboratories. The aim of this contribution is to critically review the methodology behind electronic noses. Traditional ideas of analytical measurement processes need to be better adapted to the electronic nose approaches. Novel and better fitting terms are introduced. Moreover, the transformation and loss of information that is inevitably connected to the electronic nose methodology, is discussed in detail.