Device and method for the quantitive determination of nitrogen oxides in exhaled air and application thereof

• US 20040133116A1
• Filed: 10/30/2003
• Published: 07/08/2004
• Est. Priority Date: 04/30/2001
• Status: Active Grant

• Current Assignee: Robert Bosch GmbH
• Original Assignee: Siemens AG
• Inventors: Abraham-Fuchs, Klaus, Meixner, Hans, Fleischer, Maximilian, Rumpel, Eva, Simon, Elfriede
• Granted Patent: US 7,704,214 B2
• Time in Patent Office: Days
• US Class Current: 600/532
• CPC Class Codes: A61B 5/082 Evaluation by breath analysis, e.g. determination of the chemical composition of exhaled breath A61B5/083, A61B5/091 take precedence
• CPC Class Codes: A61B 5/097 Devices for facilitating collection of breath or for directing breath into or through measuring devices
• CPC Class Codes: G01N 27/4143 Air gap between gate and channel, i.e. suspended gate [SG] FETs work function measurement per se G01N27/002
• CPC Class Codes: G01N 33/0013 by a chemical reaction G01N33/0024 takes precedence
• CPC Class Codes: G01N 33/0037 for NOx
• CPC Class Codes: G01N 33/497 of gaseous biological material, e.g. breath
• CPC Class Codes: Y02A 50/20 Air quality improvement or preservation, e.g. vehicle emission control or emission reduction by using catalytic converters

Abstract

A volumetric flow of an analyte, including exhaled air, is fed to a gas sensor unit by used of gas flow device, which can include various sensors for the determination of nitrogen oxides. An oxidation catalyst is used when using an NO₂ sensor, which converts nitrogen monoxide to nitrogen dioxide and the gas sensor unit measures the content of nitrogen dioxide. The nitrogen monoxide content is calculated from the nitrogen dioxide content. In order to eliminate cross-sensitivity moisture and ethanol are also measured. The device can be applied to the determination of nitrogen monoxide content of exhaled air.

Claims

1. Device for the quantitative measurement of nitrogen monoxide in exhaled air by means of a gas sensor unit with at least one gas sensor, with at least one gas sensor being a semi-conducting metal oxide gas sensor or a sensor based on the principle of exit work measurement and the gas sensor unit having further sensors for the detection of moisture or ethanol for elimination of cross-sensitivities.

2. Device according to claim 1, with a hybrid field effect transistor in which the gas-sensitive layer is represented by a gate electrode spaced apart from the channel area being used to read the exit work.

3. Device according to one of claims 1 or 2, with a field effect transistor being present to read the exit work, with a gas-sensitive layer being in the form of porous material deposited on the channel area.

4. Device according to one of claims 2-3, with the gas sensors being field effect transistors of a hybrid flip-chip construction.

5. Device according to one of the preceding claims, with a gas-insensitive reference layer additionally present in a gas sensor unit.

6. Device according to one of the preceding claims, with one of the gas-sensitive layers for nitrogen oxide detection containing a porphine pigment as a gas-sensitive material or being represented by same.

7. Device according to claim 6, with one of the porphine pigments being a phthalocyanine or a derivate of same, with the central atom being copper, lead, tin, nickel, cobalt or zinc, or a phthalocyanine without a central atom whose free binding sites in the porphine ring are saturated by hydrogen atoms.

8. Device according to claim 7, with the phthalocyanine without a central atom being heliogen blue G or a phthalocyanine with phenylether side chains.

9. Device according to claim 6, with one of the porphine pigments being a porphyrine or metalloporphyrine with cobalt as a central atom or a porphyrine without a central atom.

10. Device according to claim 9, with the metaloporphyrine being represented by cobalt-protoporphyrine IX chloride or the porphyrine without a central atom by protoporphyrine IX sodium salt.

11. Device according to one of claims 1-5, with the materials for gas-sensitive layers for nitrogen oxide detection being fine crystalline metal oxides such as SnO₂, WO₃, In₂O₃ salts from the carbonate system barium carbonate or polysiloxanes.

12. Device according to one of the preceding claims, with the material for gas-sensitive layers for detection of moisture being polyamides or polypyrrolidones and being polysiloxanes for the detection of ethanol.

13. Device according to one of the preceding claims, with the measuring device for determining the nitrogen monoxide in exhaled air being mobile.

14. Device according to one of the preceding claims, with a gas flow device for the supply of the volumetric flow of nitrogen dioxide or nitrogen dioxide and one or more components such as moisture, ethanol or temperature.

15. Device according to claim 14, with the volumetric flow of the exhaled air being divided in the gas flow device into a part volumetric flow via an oxidation catalyst for oxidation of nitrogen monoxide to nitrogen dioxide and then to the gas sensor unit for measurement of the nitrogen dioxide concentration, and into a further part volumetric flow that is supplied directly to a further nitrogen dioxide gas sensor for determining the nitrogen dioxide concentration, with it being possible to calculate the nitrogen monoxide concentration of the exhaled air by means of the individual nitrogen dioxide concentrations.

16. Device according to claim 14, with the complete volumetric flow of the exhaled air in the gas flow device being supplied through an oxidation catalyst for oxidation of nitrogen monoxide to nitrogen dioxide and then to a gas sensor unit for measurement of the nitrogen dioxide concentration, with it being possible to calculate the nitrogen monoxide concentration of the exhaled air by means of the nitrogen dioxide concentration.

17. Device according to one of claims 15 or 16, with one or more substances from the group of permanganate salts or perchlorate salts being applied to a support such as zeolite, aluminum oxide or silica gel as the material for an oxidation catalyst.

18. Device according to one of the preceding claims, with it being possible to supply sensor signals processed in an analytical circuit to a data network.

19. Device according to one of claims 14-18, with the gas flow device being provided with a fixed or variable restrictor device for generation of a flow resistance.

20. Method for operation of a device corresponding to one of claims 1-19, consisting of the following steps:

Exhaled air is supplied as a measured gas through an oxidation catalyst to oxidize NO to NO₂.

The measured gas is then applied to the gas sensor unit where the NO₂ content is measured.

The NO content is calculated from the NO₂ content.

This is purged with nitrogen dioxide-free air for regeneration of the gas sensor measuring system.

21. Method according to claim 20, with nitrogen-dioxide-free air being processed for inhalation to elimination environmental influences.

22. Method according to claim 20 or 21, with nitrogen-dioxide-free air being generated in a scrubber or separator device for NO_x.

23. Use of a device for quantitative measurement of nitrogen oxides in exhaled air corresponding to one of claims 1 to 19 for determining the concentration of nitrogen monoxide in the exhaled air.

24. Use according to claim 23, with the measured signals from an analytical circuit of the device being transmittable to and within an electronic network.

25. Use according to one of claims 23 or 24, with the measuring device being used to detect asthma illnesses or inflammation of the lungs.