Tracer to compensate for environmental variations that influence a chemical vapor sensor measurement

摘要

A chemical vapor sensor is provided that passively measures a suspect chemical species of interest with high sensitivity and chemical specificity, for use with safety systems. A vapor concentrator amplifies a suspect chemical vapor concentration to a detectible level, for use with an infrared detector. Compensation is provided for environmental variations that may influence the passive measurement of the chemical vapor sensor. Environmental variations may include extrinsic vapors in the surrounding air, or air currents that divert the sample vapor as it drifts from the suspect vapor source to a sampling intake. In an example, ethanol vapor is measured and carbon dioxide tracer measurements are used to calculate an ethanol vapor measurement that is adjusted for environmental variations. In an aspect, a time artifact filter sets the output of the carbon dioxide sensor to match the time dependence of the ethanol sensor, to calculate blood alcohol concentration.