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

• US 20070077176A1
• Filed: 10/05/2005
• Published: 04/05/2007
• Est. Priority Date: 10/05/2005
• Status: Active Grant

• Current Assignee: Aptiv Technologies AG (Aptiv PLC)
• Original Assignee: Vodafone Group PLC
• Inventors: Sultan, Michel, Lambert, David, Partin, Dale
• Granted Patent: US 7,736,903 B2
• Time in Patent Office: Days
• US Class Current: 422/82.50
• CPC Class Codes: B60K 28/063 preventing starting of vehicles
• CPC Class Codes: B60W 2540/24 Drug level, e.g. alcohol
• CPC Class Codes: G01N 1/2214 by sorption
• CPC Class Codes: G01N 1/405 by adsorption or absorption
• CPC Class Codes: G01N 2001/2276 Personal monitors
• CPC Class Codes: G01N 2021/158 Eliminating condensation
• CPC Class Codes: G01N 21/0332 with temperature control control of temperature G05D23/00; cryostats F17C3/08
• CPC Class Codes: G01N 21/05 Flow-through cuvettes G01N21/09 takes precedence; handling fluid samples G01N1/10
• CPC Class Codes: G01N 21/274 Calibration, base line adjustment, drift correction
• CPC Class Codes: G01N 21/3504 for analysing gases, e.g. multi-gas analysis
• CPC Class Codes: G01N 33/004 CO or CO2
• CPC Class Codes: G01N 33/0047 Organic compounds
• CPC Class Codes: G01N 33/4972 Determining alcohol content for vehicle safety devices B60K28/06
• CPC Class Codes: Y02A 50/20 Air quality improvement or preservation, e.g. vehicle emission control or emission reduction by using catalytic converters
• CPC Class Codes: Y10S 436/90 Breath testing
• CPC Class Codes: Y10T 436/204165 Ethanol

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.

Claims

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; and

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 wherein a processor calculates an adjusted suspect vapor measurement utilizing the suspect vapor, the first tracer vapor measurement and the second tracer vapor measurement.

2. The chemical vapor sensor as in claim 1, wherein the sample volume of air is sampled from a motor vehicle cabin, and wherein 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.

3. The chemical vapor sensor as in claim 2, 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.

4. The chemical vapor sensor as in claim 2, wherein the processor calculates blood alcohol concentration (BAC) utilizing the adjusted suspect vapor measurement.

5. The chemical vapor sensor as in claim 2, wherein the ambient air is sampled from an air vent providing air to the motor vehicle cabin.

6. The chemical vapor sensor as in claim 2, further comprising a time artifact filter for receiving the first tracer and second tracer carbon dioxide measurements and matching the time dependence of the ethanol vapor measurement, to calculate blood alcohol concentration (BAC).

7. The chemical vapor sensor as in claim 1, further comprising:

an infrared filter for selecting one of a range of infrared frequency and wavelength that is adsorbed by a predetermined chemical species of interest;

an infrared absorption cell defining an inlet for taking in the sample volume of air, and an outlet for expelling the sample volume of air; and

an air flow source for forcing the sample volume of air from the sampling intake, through the vapor adsorber and through the infrared absorption cell.

8. The chemical vapor sensor as in claim 2, wherein the infrared detector measures ethanol concentration in the sample volume of air of at least 0.1 parts per million (ppm).

9. The chemical vapor sensor as in claim 2, further comprising a microcontroller for instructing a safety system response if a predetermined value of the adjusted ethanol vapor concentration is exceeded in the vehicle cabin, wherein the safety response includes increasing a minimum headway distance behind a preceding vehicle, warning passengers to fasten seat belts, constraining vehicle performance, transmitting vehicle cabin ethanol measurements to police and to a vehicle recorder.

10. A method for passively measuring ethanol vapor from a person and compensating for environmental variations comprising:

measuring ethanol vapor from a person'"'"'s exhaled respiration, a carbon dioxide first tracer from the person'"'"'s exhaled respiration and a carbon dioxide second tracer from ambient air, and

calculating an adjusted ethanol vapor measurement utilizing the ethanol vapor measurement, the carbon dioxide first tracer measurement and the carbon dioxide second tracer measurement.

11. The method as in claim 10, wherein calculating the adjusted ethanol vapor measurement comprises calculating a product of the ethanol vapor measurement and carbon dioxide typically in a person'"'"'s exhaled respiration, divided by a difference of the carbon dioxide first tracer measurement and the carbon dioxide second tracer measurement.

12. The method as in claim 10, wherein the processor calculates blood alcohol concentration (BAC) utilizing the adjusted ethanol vapor measurement.

13. The method as in claim 10, wherein the ethanol vapor from a person'"'"'s exhaled respiration is sampled from a motor vehicle cabin.

14. The method as in claim 13, wherein the ambient air is sampled from an air vent providing air to the motor vehicle cabin.

15. The method as in claim 10, further comprising employing a time artifact filter to receive the first tracer and second tracer carbon dioxide measurements and match the time dependence of the ethanol vapor measurement, to calculate blood alcohol concentration (BAC).

16. A method for passively measuring a chemical vapor and compensating for environmental variations on sampling comprising:

measuring an intensity of infrared waves generated from an infrared source utilizing an 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, and passing the sample volume of air to the vapor concentrator;

measuring a suspect vapor, a first tracer vapor and a second tracer vapor from the sample volume of air; and

calculating an adjusted suspect vapor measurement utilizing the suspect vapor, the first tracer vapor measurement and the second tracer vapor measurement.

17. The method as in claim 16, wherein the sample volume of air is sampled from a motor vehicle cabin, and wherein 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.

18. The method as in claim 17, wherein calculating the adjusted suspect vapor measurement comprises 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.

19. The method as in claim 17, further comprising calculating a blood alcohol concentration (BAC) utilizing the adjusted suspect vapor measurement.

20. The method as in claim 17, wherein the ambient air is sampled from an air vent providing air to the motor vehicle cabin.

21. The method as in claim 17, further comprising employing a time artifact filter to receive the first tracer and second tracer carbon dioxide measurements and match the time dependence of the ethanol vapor measurement, to calculate blood alcohol concentration (BAC).

22. The method as in claim 16, further comprising:

selecting one of a range of infrared frequency and wavelength that is adsorbed by a predetermined chemical species of interest, utilizing an infrared filter;

defining an inlet utilizing an infrared absorption cell, for taking in the sample volume of air, and an outlet for expelling the sample volume of air; and

forcing the sample volume of air, utilizing an air flow source, from the sampling intake, through the vapor adsorber and through the infrared absorption cell.

23. The method as in claim 17, further comprising instructing a safety system response if a predetermined value of the adjusted ethanol vapor concentration is exceeded in the vehicle cabin, wherein the safety response includes increasing a minimum headway distance behind a preceding vehicle, warning passengers to fasten seat belts, constraining vehicle performance, transmitting vehicle cabin ethanol measurements to police and to a vehicle recorder.