Tracer to compensate for environmental variations that influence a chemical vapor sensor measurement
First Claim
1. A chemical vapor sensor that compensates for environmental variations comprising:
- an infrared source for generating infrared waves;
an infrared detector for measuring an intensity of the infrared waves generated from the infrared source;
a vapor concentrator including a vapor adsorber and a heating source to heat the vapor adsorber, for concentrating vapor from a sample volume of air, wherein the concentrated vapor is passed into a path of the infrared waves;
a sampling intake for passively acquiring the sample volume of air and passing the sample volume of air to the vapor concentrator;
wherein a suspect vapor, a first tracer vapor and a second tracer vapor are measured from the sample volume of air and the sample volume of air is sampled from a motor vehicle cabin, and the suspect vapor is ethanol vapor from a person'"'"'s exhaled respiration, the first tracer vapor is carbon dioxide from the person'"'"'s exhaled respiration, and the second tracer vapor is carbon dioxide from ambient air from the motor vehicle; and
a processor configured to calculate an adjusted suspect vapor measurement utilizing the suspect vapor, the first tracer vapor measurement and the second tracer vapor measurement, wherein the processor calculates the adjusted suspect vapor measurement by calculating a product of the ethanol suspect vapor measured and carbon dioxide tracer typically in a person'"'"'s exhaled respiration, divided by a difference of the carbon dioxide first tracer vapor measured and the carbon dioxide second tracer vapor measured from ambient air.
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Accused Products
Abstract
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.
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Citations
18 Claims
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1. A chemical vapor sensor that compensates for environmental variations comprising:
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an infrared source for generating infrared waves; an infrared detector for measuring an intensity of the infrared waves generated from the infrared source; a vapor concentrator including a vapor adsorber and a heating source to heat the vapor adsorber, for concentrating vapor from a sample volume of air, wherein the concentrated vapor is passed into a path of the infrared waves; a sampling intake for passively acquiring the sample volume of air and passing the sample volume of air to the vapor concentrator;
wherein a suspect vapor, a first tracer vapor and a second tracer vapor are measured from the sample volume of air and the sample volume of air is sampled from a motor vehicle cabin, and the suspect vapor is ethanol vapor from a person'"'"'s exhaled respiration, the first tracer vapor is carbon dioxide from the person'"'"'s exhaled respiration, and the second tracer vapor is carbon dioxide from ambient air from the motor vehicle; anda processor configured to calculate an adjusted suspect vapor measurement utilizing the suspect vapor, the first tracer vapor measurement and the second tracer vapor measurement, wherein the processor calculates the adjusted suspect vapor measurement by calculating a product of the ethanol suspect vapor measured and carbon dioxide tracer typically in a person'"'"'s exhaled respiration, divided by a difference of the carbon dioxide first tracer vapor measured and the carbon dioxide second tracer vapor measured from ambient air. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A method for passively measuring ethanol vapor from a person and compensating for environmental variations comprising:
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measuring an ethanol vapor concentration and a carbon dioxide second tracer from ambient air at a first time period; measuring ethanol vapor from a person'"'"'s exhaled respiration and a carbon dioxide first tracer from the person'"'"'s exhaled respiration at a same location as the ethanol vapor concentration and the carbon dioxide second tracer, but at a second time period, and calculating an adjusted ethanol vapor measurement utilizing the ethanol vapor measurements, the carbon dioxide first tracer measurement and the carbon dioxide second tracer measurement, wherein calculating the adjusted ethanol vapor measurement comprises calculating a product of the ethanol vapor measurement and carbon dioxide normally in a person'"'"'s exhaled respiration when the person has a blood alcohol concentrations (BAC) of about 0.8 g/dL or less, divided by a difference of the carbon dioxide first tracer measurement and the carbon dioxide second tracer measurement. - View Dependent Claims (9, 10, 11, 12)
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13. A method for passively measuring a chemical vapor and compensating for environmental variations on sampling comprising:
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measuring an intensity of infrared waves generated from an infrared source utilizing an infrared detector, wherein the infrared waves pass from the infrared source across an absorption cell to the infrared detector; employing a vapor concentrator including a vapor adsorber and a heating source to heat the vapor adsorber, to concentrate vapor from a sample volume of air, wherein the concentrated vapor is passed into a path of the infrared waves; acquiring the sample volume of air utilizing a passive sampling intake independent of an active involvement of a person, and passing the sample volume of air to the vapor concentrator, wherein the sample volume of air is sampled from a motor vehicle cabin, and the suspect vapor is ethanol vapor from a person'"'"'s exhaled respiration, the first tracer vapor is carbon dioxide from the person'"'"'s exhaled respiration, and the second tracer vapor is carbon dioxide from ambient air from the motor vehicle; measuring a suspect vapor, a first tracer vapor, and a second tracer vapor from the sample volume of air, wherein the second tracer vapor is obtained at a same location, but during a different time period than the first tracer vapor; and calculating an adjusted suspect vapor measurement utilizing the suspect vapor, the first tracer vapor measurement and the second tracer vapor measurement, wherein calculating the adjusted suspect vapor measurement comprises calculating a product of the ethanol suspect vapor measured and carbon dioxide tracer normally in a person'"'"'s exhaled respiration when the person'"'"'s blood alcohol concentration (BAC) is 0.8 g/dL or less, divided by a difference of the carbon dioxide first tracer vapor measured and the carbon dioxide second tracer vapor measured from ambient air. - View Dependent Claims (14, 15, 16, 17, 18)
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Specification