The smell test
Kate Prigge of the Monell Chemical Senses Center studies what things smell like—to us, to canines, and to machines. By using many different sensing technologies, from mass spectrometers to working dogs, she is honing in on the smells that signal health and disease. In her latest work, Prigge is getting help from medical working dogs that are able to smell ovarian cancer in patient samples. The next step is to design a machine that can do as good a job as a German Sheperd in picking out odors linked to the disease.
Why do human odors matter?
Our odors can be a sign of where we’ve been, what we’ve eaten, or even offer clues about health and illness. There’s a lot of identity information bound up in the way we smell—our odor profile is like a chemical fingerprint. We can learn about ethnicity, gender, age, all types of things from body odor. This identity information is even used by people—mothers can pick out their newborn’s odor and vice versa.
Olfaction is a much different sense than our sense of sight or hearing. The latter senses work on a continuum—the spectrum of light or range of sound frequencies have definite ends. In the smell space, odors are made of all different kinds of molecules that vary in many dimensions. Our noses integrate these complex mixtures and interpret them as one or a few odors. In order to make a mechanical nose that can compete with a human or dog nose, we need to know a lot more about how biological noses work—from the way our noses pick up molecules to the way our brains process the signals. Mechanical noses must also be able to bind up smelly molecules and let them go, over and over: something our noses are good at but is a tough prospect for designed materials.