Nanostructured sensor for high temperature applications

• US 20080128274A1
• Filed: 12/04/2006
• Published: 06/05/2008
• Est. Priority Date: 12/04/2006
• Status: Abandoned Application

• Current Assignee: Honeywell International Inc.
• Original Assignee: Honeywell International Inc.
• Inventors: Kumar, Ramsesh Anil, Raghurama, Raju A.
• Application Number:
  US11/633,776
• Publication Number:
  US 20080128274A1
• Time in Patent Office: Days
• US Class Current: 204/290.1
• CPC Class Codes: B82Y 30/00 Nanotechnology for materials or surface science, e.g. nanocomposites
• CPC Class Codes: G01N 27/127 comprising nanoparticles
• CPC Class Codes: G01N 33/0037 NOx
• 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 gas sensor utilizes nano-sized CeO₂ and doped CeO₂ particles for detecting NO, NO2 and also for studying the cross sensitivity of oxygen, un-burnt hydrocarbons, CO and CO₂. Nano-crystalline powders of CeO₂ and doped CeO₂ are employed to configure thin films on Platinum comb type electrodes preformed on alumina substrates. Various catalytic oxides are employed to convert the NO to NO₂ to get equal response to NOx gas. Gas sensing properties are measured using a dynamic chamber with a constant flow of air and NOX gas in required percentage in nitrogen gas.

Claims

1. A method of providing a CeO₂ NO_x gas sensor, comprising:

providing a substrate;

forming a pair of interdigital electrodes on a side of said substrate and a heater another side of said substrate; and

applying a coating of nano-crystalline powders of doped CeO₂ on said pair of interdigital electrodes formed on said substrate in order to form a CeO₂ NO_x gas sensor.

2. The method of claim 1 further comprising configuring said pair of interdigital electrodes in a comb-type configuration upon said side of said substrate and said another side of said substrate.

3. The method of claim 1 wherein said substrate comprises alumina or such similar substrates of low thermal expansion coefficient.

4. The method of claim 1 wherein said substrate comprises a ceramic material or a semi-conducting material

5. The method of claim 1 further comprising configuring a heater upon said substrate wherein said heater and said pair of interdigital electrodes comprise platinum.

6. The method of claim 1 further comprising providing a catalyst material in order to convert NO to NO₂ and thereby detect NOx gas for any combination of NO and NO₂ by said CeO₂ NOx gas sensor and provide a same output thereof.

7. The method of claim 5 further comprising forming said heater utilizing a screen printing on said substrates following a sintering at a temperature of 1000°

C.

8. The method of claim 1 wherein applying a coating of nano-crystalline powders of CeO₂ on said pair of interdigital electrodes formed on said substrate, further comprises:

synthesizing a nano-crystalline powder by employing a sol-gel and a chemical vapor synthesis;

dispersing said nano-crystalline powder in an organic solvent;

employing a dip coating or an electrophoresis operation to fabricate at least one thin film for deposition upon said substrate;

carrying out sintering operation to enhance an adherence of said at least one thin film to said substrate; and

adding a catalytic mesh of noble metal.

9. The method of claim 7 wherein said sintering operation is carried out by adding an inorganic binding mixture.

10. The method of claim 7 wherein said nano-crystalline powder is mixed with an equal amount of ethylene glycol and a paste applied thereafter to say on to said pair of interdigital electrodes.

11. A method of providing a CeO₂ NO_x gas sensor, comprising:

providing a substrate;

forming a pair of interdigital electrodes on a side of said substrate and a heater another side of said substrate;

configuring said pair of interdigital electrodes in a comb-type configuration upon said side of said substrate and said another side of said substrate; and

applying a coating of nano-crystalline powders of doped CeO₂ on said pair of interdigital electrodes formed on said substrate in order to form a CeO₂ NO_x gas sensor.

12. The method of claim 11 wherein said substrate comprises alumina or such similar substrates of low thermal expansion coefficient.

13. The method of claim 11 wherein said substrate comprises a ceramic material or a semi-conducting material

14. The method of claim 11 further comprising:

providing a catalyst material in order to convert NO to NO₂ and thereby detect NOx gas for any combination of NO and NO₂ by said CeO₂ NO_x gas sensor and provide a same output thereof; and

forming said heater utilizing a screen printing on said substrates following a sintering at a temperature of 1000°

C.

15. The method of claim 11 wherein applying a coating of nano-crystalline powders of CeO₂ on said pair of interdigital electrodes formed on said substrate, further comprises:

synthesizing a nano-crystalline powder by employing a sol-gel and a chemical vapor synthesis;

dispersing said nano-crystalline powder in an organic solvent;

employing a dip coating or an electrophoresis operation to fabricate at least one thin film for deposition upon said substrate;

carrying out sintering operation to enhance an adherence of said at least one thin film to said substrate; and

adding a catalytic mesh of noble metal.

16. A CeO₂ NO_x gas sensor apparatus, comprising:

a substrate;

a pair of interdigital electrodes configured on a side of said substrate and a heater another side of said substrate; and

a coating of nano-crystalline powders of doped CeO₂ applied on said pair of interdigital electrodes formed on said substrate in order to form a CeO₂ NO_x gas sensor.

17. The apparatus of claim 16 wherein said pair of interdigital electrodes are arranged in a comb-type configuration upon said side of said substrate and said another side of said substrate.

18. The apparatus of claim 16 wherein said substrate comprises alumina or such similar substrates of low thermal expansion coefficient.

19. The apparatus of claim 16 wherein said substrate comprises a ceramic material or a semi-conducting material

20. The apparatus of claim 16 further comprising a heater configured upon said substrate wherein said heater and said pair of interdigital electrodes comprise platinum.