The whiffer

The whiffer is the part of the system that emits the smell imitation to the surroundings. It must include a palette of reservoirs containing the odorants it can mix, a technology to accurately mix them, and means for releasing them to the outside world in accurate quantities and with precise timing. For use by mass consumers, the sniffer should also have small physical dimensions and be of low cost. This definition of a whiffer strongly relies on the assumption that mixtures from within a set of odorants can mimic, to a reasonable level, any desired smell. This is reminiscent of the characteristics of RGB color mixing in vision.

The requirements from a whiffer seem simple, but it turns out that numerous technological barriers must be overcome in order to satisfy them. In fact, whiffers, as we have defined them, are not commercially available. The devices that are closest to being whiffers are the olfactometers, which have been in use for many years and are capable of accurately mixing gas samples and releasing the mixture to the surroundings. They are most often used together with human panelists for the purpose of assessing odor emission levels. However, an olfactometer is not a true whiffer, since it is designed mainly for diluting carefully prepared gaseous samples. We think of a whiffer as being more akin to a printer (say, an ink-jet), with the palette of odorants being analogous to the color cartridge.