An olfactometer is a device which, as one might imagine from the name, is involved in the measurement of smell. There are two different kinds of olfactometer. One acts as a sort of artificial nose which is capable of detecting odors at various concentrations, including concentrations so low that the human nose cannot detect them. The other is a device which is designed to measure how acute someone's sense of smell is, typically for use in a clinical context.
Olfactometers in the sense of artificial noses are used in a number of settings. They are classically handheld devices, with small filter pads through which air is passed. When odorous compounds are detected, the device can set off an alarm or provide a readout. Often, sensitivity can be adjusted for different settings, and it may also be possible to sensitize the device to specific types of smells.
One setting in which olfactometers are used is perfumery, in which smells are analyzed with the assistance of such a device, and these devices are also used for quality consistency. They can also be used as alarms, as some odorous compounds are dangerous to human health; for example, modified olfactometers can be placed in chemical facilities and mines to detect dangerous releases of gas. One interesting experimental use of the olfactometer is in forensics, where some researchers have explored the idea of using such devices to “sniff” for chemical compounds associated with the decay process to learn more about when someone died.
Another use of the olfactometer is in research studies or in the clinical environment, where it can be a useful diagnostic tool to test acuity when it comes to the sense of smell. Having an impaired sense of smell can be a sign of a medical issue such as a tumor, or may be associated with a congenital condition. Using an olfactometer, a doctor can isolate the problem, and determine how serious it is. For example, a patient may be able to smell some things but not others, may misinterpret smells, may smell things when no odor-producing compound is present, and forth. This information can be valuable to have.
Olfactometers tend to be quite expensive. They are very sensitive and delicate instruments, and it's also necessary to periodically replace filters and attachments to keep the device in good working order. Scientific companies may supply them by order, and people can also order them from manufacturers of diagnostic equipment.