The Cyrano electronic nose (first developed by Cyrano Sciences in partnership with Warwick University), is a small, handheld electronic nose. The measurement is based on a change in resistance of each chemical sensor in the 32-sensor NoseChip when exposed to a chemical vapour. This is a differential measurement with the sensor response measured as (Rmax-Ro)/ Ro, with Ro being the resistance during a baseline gas flow and Rmax being the maximum resistance during exposure to the sample vapour.
This instrument employs composite polymer sensors (a combination of a insulating rubber and conducting carbon black, where the carbon endows conductive properties to the resultant mix). When exposed to a vapour, the polymer swell reducing the number of conductive paths through the sensor and thus increasing its resistance. This change in resistance is then used for pattern recognition software built into the Cyrano.
More information can be seen on the Cyrano Website