The problem with using our nose and brain, as an analytical tool, is that they provide a subjective analysis. For example, country dwellers tend to find agricultural smells as offensive as those who live in towns. The electronic nose mimics some of the characteristics of the human nose but is not subjective. The model we are using is a new portable electronic nose (Cyranose 320) supplied by our research partner Cyrano Sciences. It contains 32 individual sensors, each of which is made from a different organic polymer-carbon black combination. When the sensors are exposed to an odour they expand slightly and this causes a change in their electrical conductivity. This change, which is usually different for each sensor, is recorded. The pattern of response from the 32 sensors varies for different odours. Sophisticated computer programs are used to compare the pattern from an unknown material with a library of known patterns. An identification of a new sample can be made if it matches any of the known patterns in the library.
Our aim is to test this new sensor technology in a practical application to help solve problems associated with odours released from industrial and other sites and which cause a nuisance to the general public.The human nose is incredibly sensitive to odorous compounds - often detecting concentrations of a few parts per billion. However, the Cyranose 320 is not as sensitive as the human nose, and, in order to detect odours at such low concentrati
ons, an odorous sample needs to be preconcentrated before it is sampled by the nose. The preconcentration system used is the EDU by Airsense Analytics. This system was chosen as it is small, light weight and can be powered by a battery.