Ethyl alcohol sensor and method of use

A passive ethanol sensing unit located in a passenger compartment of a vehicle, the sensing unit comprising:

• an adsorbent material capable of adsorbing ethanol vapors;
• means for flowing air from the passenger compartment over the adsorbent material to cause adsorption by the adsorbent material of any ethanol vapors contained in the air while the adsorbent material is at a first temperature;
• means for heating the adsorbent material to a second temperature higher than the first temperature so as to release ethanol vapors from the adsorbent material;
• means for delaying operation of the heating means for a predetermined period of time during which the adsorbent material adsorbs ethanol vapors from the air flowed over the adsorbent material by the flowing means;
• means for measuring the concentration of the ethanol vapors released from the adsorbent material when heated by the heating means and providing an output ethanol concentration signal based on the measured concentration:
• means for sensing a state of a system of the vehicle that is capable of altering the concentration of vapors in the passenger compartment;
• and
• means for modifying the output ethanol concentration signal responsive to the sensed state of a system of the vehicle that is capable of altering the concentration of vapors in the passenger compartment to provide a datum indicative of alcohol impairment of a vehicle driver in the passenger compartment.

A method of sensing ethanol vapors in a passenger compartment of a vehicle, the method comprising the steps of:

• collecting ethanol vapors from an air sample from an air sample taken from the passenger compartment with a collecting means at a first temperature;
• after a predetermined period of lime during which the collecting means to collects ethanol vapors from the air sample, heating the collecting means to a second temperature higher than the first temperature so as to release ethanol vapors from the collecting means;
• sensing ethanol vapors released from the collecting means when heated and providing therefrom an output ethanol concentration signal;
• sensing a state of a system of the vehicle that is capable of altering the concentration of vapors in the passenger compartment;
• and then modifying the output ethanol concentration signal responsive to the sensed state of a system of the vehicle that is capable of altering the concentration of vapors in the passenger compartment to provide a datum indicative of alcohol impairment of a vehicle driver in the passenger compartment.