Chemical vapor sensor

• US 20060154377A1
• Filed: 01/12/2005
• Published: 07/13/2006
• Est. Priority Date: 01/12/2005
• Status: Active Grant

• Current Assignee: Aptiv Technologies AG (Aptiv PLC)
• Original Assignee: Delphi Technologies, Inc. (Aptiv PLC)
• Inventors: Thrush, Christopher M., Oberdier, Larry M., Lambert, David K.
• Granted Patent: US 7,700,044 B2
• Time in Patent Office: Days
• US Class Current: 436/167
• CPC Class Codes: B60K 28/06 responsive to incapacity of driver
• CPC Class Codes: B82Y 30/00 Nanotechnology for materials or surface science, e.g. nanocomposites
• 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 21/3504 for analysing gases, e.g. multi-gas analysis
• CPC Class Codes: G01N 2201/12707 Pre-test of apparatus, e.g. dark test, sensor test
• CPC Class Codes: G01N 2201/12792 Compensating own radiation in apparatus
• CPC Class Codes: G01N 33/4972 Determining alcohol content for vehicle safety devices B60K28/06

Abstract

A chemical vapor sensor is provided that passively measures a chemical species of interest with high sensitivity and chemical specificity. In an aspect, ethanol vapor in a vehicle cabin is measured, and sufficient sensitivity is provided to passively detect a motor vehicle driver that exceeds a legal limit of blood alcohol concentration (BAC), for use with vehicle safety systems. The sensor can be situated in an inconspicuous vehicle cabin location and operate independently without requiring active involvement by a driver. A vapor concentrator is utilized to amplify a sampled vapor concentration to a detectible level for use with an infrared (IR) detector. In an aspect, in comparison to conventional chemical sensors, the sensitivity of detection of ethanol vapor is increased by a factor of about 1,000. Further, a single channel of infrared detection is utilized avoiding spurious infrared absorption and making the chemical vapor sensor less costly to implement.

Claims

1. A chemical vapor sensor comprising:

an infrared source for generating infrared waves;

an infrared detector for measuring the intensity of the infrared waves generated from the infrared source; and

a vapor concentrator including a vapor adsorber and a heating source to heat the vapor adsorber, for transferring concentrated vapor into a path of the infrared waves.

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

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

an infrared absorption cell defining an inlet for taking in air, and an outlet for expelling air; and

an air flow source for controlling air flow through the vapor adsorber and through the infrared absorption cell.

3. The chemical vapor sensor as in claim 1, wherein the vapor concentrator, infrared source, and infrared detector measure ethanol vapor.

4. The chemical vapor sensor as in claim 3, wherein the ethanol vapor is sampled from the cabin of a vehicle without requiring active involvement of a vehicle driver.

5. The chemical vapor sensor as in claim 3, wherein the infrared detector measures ethanol concentration in air of at least 0.1 parts per million (ppm).

6. The chemical vapor sensor as in claim 5, wherein the infrared detector measures ethanol concentration in air of 0.1 ppm to 10 ppm, including a standard deviation.

7. The chemical vapor sensor as in claim 1, wherein the vapor adsorber material is one of carbon, carbon molecular sieves, activated carbon, carbon nanotubes, porous organic polymer, inorganic materials having a high surface area and zeolite.

8. The chemical vapor sensor as in claim 3, further comprising a microcontroller for instructing and carrying out a safety system response if a predetermined ethanol concentration is exceeded in the vehicle cabin, wherein the safety response includes increasing a minimum headway distance behind a preceding vehicle, constraining vehicle performance, transmitting vehicle cabin ethanol measurements to police and to a vehicle recorder.

9. A passive chemical vapor sensor for sampling ethanol vapor from a vehicle cabin comprising:

an infrared source for generating infrared waves;

an infrared detector for measuring the intensity of the infrared waves generated from the infrared source;

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

an infrared absorption cell defining an inlet for taking in air, and an outlet for expelling air;

a vapor concentrator including a vapor adsorber and a heating source to heat the vapor adsorber, for transferring concentrated vapor into a path of the infrared waves; and

an air flow source for controlling air flow through the vapor adsorber and through the infrared absorption cell.

10. The passive chemical vapor sensor as in claim 9, wherein the infrared detector measures ethanol concentration in air of at least 0.1 parts per million (ppm).

11. The passive chemical vapor sensor as in claim 10, wherein the infrared detector measures ethanol concentration in air of 0.1 ppm to 10 ppm, including a standard deviation.

12. The passive chemical vapor sensor as in claim 9, wherein the vapor adsorber material is one of carbon, carbon molecular sieves, activated carbon, carbon nanotubes, porous organic polymer, inorganic materials having a high surface area, and zeolite.

13. The passive chemical vapor sensor as in claim 9, further comprising a microcontroller for instructing and carrying out a safety system response if a predetermined ethanol concentration is exceeded in the vehicle cabin, wherein the safety response includes increasing a minimum headway distance behind a preceding vehicle, constraining vehicle performance, transmitting vehicle cabin ethanol measurements to police and to a vehicle recorder.

14. The passive chemical vapor sensor as in claim 9, wherein the infrared detector utilizes a single absorption channel for infrared detection.

15. The passive chemical vapor sensor as in claim 9, wherein the inlet is situated in one of the vehicle cabin ceiling, dashboard, steering column, steering wheel, headrest, seat, A pillar, B pillar, and air intake vent.

16. A method of measuring a chemical vapor concentration comprising:

passing air, including sample vapor, through an adsorber;

measuring an output (designated V_off) of an infrared detector, with an infrared source deactivated;

heating the adsorber;

measuring an output (designated V_on) of the infrared detector, with the infrared source activated;

passing concentrated sample vapor from the adsorber into and through the infrared absorption cell at a predetermined time;

measuring a change in an output (designated V_sig) of the infrared detector; and

calculating the ratio V_sig/(V_on−

V_off).

17. The method of measuring a chemical vapor concentration as in claim 16, wherein passing concentrated sample vapor from the adsorber into and through the infrared absorption cell comprises:

activating air flow just long enough to transfer concentrated sample vapor from the adsorber into the infrared absorption cell;

holding the concentrated sample vapor in the infrared absorption cell for a predetermined and desired time; and

activating air flow again to purge the adsorber and the infrared absorption cell of any concentrated sample vapor.

18. The method of measuring a chemical vapor concentration as in claim 16, wherein passing air, including sample vapor, through an adsorber comprises passing vehicle cabin air through an adsorber, and wherein the sample vapor is ethanol vapor.

19. The method of measuring a chemical vapor concentration as in claim 16, wherein calculating the ratio V_sig/(V_on−

V_off) comprises utilizing a microcontroller.

20. The method of measuring a chemical vapor concentration as in claim 16, further comprising at least one of:

heating the infrared absorption cell to a temperature above the dew point of the sample vapor;

heating the adsorber on the order of 10 degrees Celsius above ambient temperature while the sample vapor is being adsorbed;

coating the inside of the infrared absorption cell with a material that prevents water droplets from nucleating;

altering the air flow through the infrared absorption cell wherein exhaust from the adsorber flows down the center of the infrared absorption cell and avoids contacting cool infrared absorption cell walls; and

forming the adsorber from a material that is more hydrophobic than carbon.

21. The method of measuring a chemical vapor concentration as in claim 16, further comprising amplifying the partial pressure of the sample vapor by at least one of isolating the adsorber as it is heated, and rapidly heating the adsorber while maintaining a constant flow of air through the adsorber.

22. The method of measuring a chemical vapor concentration as in claim 18, further comprising repetitively performing ethanol vapor detection during vehicle operation.