olfactometer

An olfactometer is a device designed to deliver controlled olfactory stimuli to a human or animal subject. It allows researchers to specify the type of odorant, the concentration, the timing, and the rate at which odorant is presented, enabling repeatable experiments on perception, discrimination, and behavior. Olfactometers are used in neuroscience, psychology, physiology, and sensory biology, as well as in industrial testing.

Most modern olfactometers are dynamic or air-dilution systems. They generate odor pulses by mixing a saturated odorant stream with clean carrier air in precisely regulated proportions, typically controlled by mass flow controllers and a computer interface. This yields known concentrations (often expressed as parts per million or odor units) and short onset and offset times. Some designs feature multiple odor channels and randomized presentation to prevent adaptation.

Applications include measuring detection thresholds and discrimination in humans, studying olfactory pathways in animals, screening attractants or repellents for insects, and evaluating environmental odors. In clinical settings, olfactometry is used to diagnose olfactory dysfunction and monitor recovery. In laboratory research, olfactometers enable stimulus-controlled experiments on learning, memory, and neural coding of odor information.

Key design considerations include preventing cross-contamination between odorants, maintaining stable temperature and humidity, and ensuring rapid stimulus onset and offset. Calibration with standard odorants and regular maintenance are essential to keep concentrations accurate. While commonly bench-top laboratory instruments exist, portable olfactometers are also used for field studies and industrial odor testing.