Passive Sensing of Driver Intoxication

A sensor that passively monitors the driver for intoxication has been demonstrated. The driver's blood alcohol concentration (BAC) is obtained by sensing alcohol and CO₂ in air drawn from the vehicle cabin. With a legally drunk driver, the steady state alcohol concentration can be as low as 0.3 ppm, even with the doors and windows closed. The sensor uses infrared transmission to quantify alcohol vapor and CO₂. A vapor concentrator increases alcohol sensitivity — an adsorber collects alcohol vapor and releases it as a concentrated burst at 1 minute intervals. A valid measure of driver BAC is ordinarily available 1.5 minutes after the driver gets in. Sensed CO₂ must be above a threshold for a valid measurement.