NOx gas sensor for automotive exhaust and air pollution monitoring

• US 20080169190A1
• Filed: 01/12/2007
• Published: 07/17/2008
• Est. Priority Date: 01/12/2007
• Status: Abandoned Application

• Current Assignee: Honeywell International Inc.
• Original Assignee: Honeywell International Inc.
• Inventors: Raghurama, Raju A., Anilkumar, Ramsesh
• Application Number:
  US11/653,758
• Publication Number:
  US 20080169190A1
• Time in Patent Office: Days
• US Class Current: 204/400
• CPC Class Codes: G01N 27/12 of a solid body in dependence upon absorption of a fluid; of a solid body in dependence upon reaction with a fluid , for detecting components in the fluid

Abstract

A NO_x gas sensor for measuring NO, NO₂ and NO_x gas content from automotive exhaust including a method for producing such a gas sensor. The NO_x gas sensor generally includes a substrate, and a plurality of electrodes preformed and located on one side of the substrate. A platinum heater is located the other and opposite side of the substrate. A coating of nano-crystalline powders of a semi-conducting oxide material can be located and configured on the plurality of electrodes preformed on the substrate, thereby forming a gas sensor for the detection of NO_x. The substrate may be composed of a ceramic material, glass, alumina and/or another type of high-melting material. The electrodes, along with the heater are preferably composed of platinum. The semi-conducting oxide material preferably comprises YMnO₃ or doped YMnO₃.

Claims

1. A NO_x gas sensor apparatus, comprising;

a substrate;

a plurality of electrodes preformed and located on one side of said substrate;

a platinum heater located on another and opposite side of said substrate; and

a coating of nano-crystalline powders of a semi-conducting oxide material located and configured on said plurality of electrodes preformed on said substrate, thereby forming a gas sensor for the detection of gases selected from a group comprising NO, NO₂ and NO_x.

2. The apparatus of claim 1 wherein said coating of nano-crystalline powders comprises Yttrium Manganese Oxide (YMnO₃), which is provided by Y_1-x R_xMn_1-y T_yO₃, where R and T represent rare-earth metals and transition metals respectively and x and y values range from 0 to 0.4.

3. The apparatus of claim 1 wherein said substrate comprises a ceramic material selected from the group comprising of alumina, zirconia, metal silicates, glass and metal phosphates.

4. The apparatus of claim 1 wherein said substrate comprises a high-melting material that has a melting point in a range between about 1000°

C. and about 2000°

C.

5. The apparatus of claim 4 wherein said material comprises glass.

6. The apparatus of claim 4 wherein said high-melting material comprises alumina.

7. The apparatus of claim 1 wherein said plurality of electrodes comprises platinum.

8. The apparatus of claim 1 wherein said semi-conducting oxide material comprises nano-crystalline Yttrium Manganese Oxide (YMnO₃) and doped Y_1-x R_xMn_1-y T_yO₃, wherein R and T represent rare-earth metals and transition metals respectively and x and y values ranging from 0 to 0.4).

9. A NO_x gas sensor apparatus, comprising;

a substrate;

a plurality of electrodes preformed and located on one side of said substrate;

a platinum heater located on another and opposite side of said substrate; and

a coating of nano-crystalline powders of a semi-conducting oxide material located and configured on said plurality of electrodes preformed on said substrate, thereby forming a gas sensor for the detection of gases selected from a group comprising NO, NO₂ and NO_x and wherein said coating of nano-crystalline powders comprises Yttrium Manganese Oxide (YMnO₃), which is provided by Y_1-x R_xMn_1-y T_yO₃, where R and T represent rare-earth metals and transition metals respectively and x and y values range from 0 to 0.4.

10. The apparatus of claim 9 wherein said substrate comprises a ceramic material selected from the group comprising of alumina, zirconia, metal silicates, glass and metal phosphates.

11. The apparatus of claim 9 wherein said substrate comprises a high-melting material that has a melting point in a range between about 1000°

C. and about 2000°

C.

12. A NO_x gas sensor method, comprising;

providing a substrate;

pre-forming and locating a plurality of electrodes on one side of said substrate;

locating a platinum heater on another and opposite side of said substrate; and

locating and configuring a coating of nano-crystalline powders of a semi-conducting oxide material on said plurality of electrodes pre-formed on said substrate, thereby forming a gas sensor for the detection of gases selected from a group comprising NO, NO₂ and NO_x.

13. The method of claim 12 wherein said coating of nano-crystalline powders comprises Yttrium Manganese Oxide (YMnO₃), which is provided by Y_1-x R_xMn_1-y T_yO₃, where R and T represent rare-earth metals and transition metals respectively and x and y values range from 0 to 0.4.

14. The method of claim 12 wherein said semi-conducting oxide material comprises nano-crystalline Yttrium Manganese Oxide (YMnO₃) and doped Y_1-x R_xMn_1-y T_yO₃, wherein R and T represent rare-earth metals and transition metals respectively and x and y values ranging from 0 to 0.4).

15. The method of claim 12 wherein said substrate comprises a ceramic material selected from the group comprising of alumina, zirconia, metal silicates, glass and metal phosphates.

16. The method of claim 12 wherein said substrate comprises a high-melting material that has a melting point in a range between about 1000°

C. and about 2000°

C.

17. The method of claim 12 wherein locating and configuring a coating of nano-crystalline powders of a semi-conducting oxide material on said plurality of electrodes pre-formed on said substrate, further comprises:

(a) synthesizing said semi-conducting oxide material with a plurality of dopants by employing a sol-gel process in order to provide a plurality of nano-sized powders;

(b) fabricating a thick and a thin film by electrophoretic deposition, dip coating and RF magnetron sputtering on said plurality of electrodes and said platinum heater; and

(c) providing a catalytic mesh in order to eliminate a plurality of gases other than NO_x from entering into said gas sensor.

18. The method of claim 12 further comprising providing a catalyst material in order to convert NO to NO₂ and thereby detect NO_x gas for any combination of NO and NO₂ and provide a same output thereof.

19. The method of claim 12 further comprising two similar YMnO₃ sensor elements mounted in an exhaust environmentally-compatible metal housing and maintained at two different temperatures to measure the NO and NO₂ gas concentrations.

20. The method of claim 12 further comprising:

providing a catalyst material above an NO_x gas sensor element in order to convert NO to NO₂ and thereby detect NO_x gas for any combination of NO and NO₂ and provide a same output thereof; and

forming said heater utilizing a screen printing on said substrate following a sintering at a temperature of 1200°

C.