Apparatus and method for early detection and identification of dilute chemical vapors

摘要: A detector and method for identifying a chemical vapor determining its concentration in the ambient atmosphere. The apparatus (120) preferably includes plurality of surface acoustic wave (SAW) devices (10), each including piezoelectric substrate (20), one-half (32) which is coated with selected polymer. polymer characteristically absorbs one or more group vapors. Diffusion into increases mass proportionately changes resonant frequency SAW device. microcomputer control (186) operative to determine predicted time constant (or rate) diffusion equilibrium within coating device identify relative atmosphere using values these parameters long before has reached vapor.