A hand-held, battery-operated odor detector is presented, the principle of action is briefly described, and potential applications are discussed.The detector consists of an array of 32 sensors, composed of conducting particles evenly dispersed in a polymer matrix.The polymer expands like a sponge when it comes in contact with vapor, increasing the elec. resistance of the composite.Each sensor responds in a different way to a given substance, thus giving a unique pattern of resistance changes.A silicon-based chip under development can contain ≤10,000 individual sensors.Applications include food and beverage industry, medial diagnostics, environmental reconnaissance, leak and hazardous substance detection, and military opportunities.