Auxiliary gas diffusion electrodes for diagnostics of electrochemical gas sensors

• US 9,377,435 B2
• Filed: 10/04/2012
• Issued: 06/28/2016
• Est. Priority Date: 10/11/2011
• Status: Active Grant

• Current Assignee: Life Safety Distribution AG (Honeywell International Inc.)
• Original Assignee: Honeywell International Inc.
• Inventors: Pratt, Keith Francis Edwin, Jones, Martin G., Chapples, John
• Primary Examiner(s): Dieterle, Jennifer
• Application Number:
  US13/644,671
• Publication Number:
  US 20130087457A1
• Time in Patent Office: 1,363 Days
• Field of Search: 204421-429, 73/233.1, 73/233.2
• US Class Current: 1/1
• CPC Class Codes: G01N 27/4045 for gases other than oxygen
• CPC Class Codes: G01N 27/4163 checking the operation of, or calibrating, the measuring apparatus G01N27/3274, G01N27/4175 and G01N33/0006 take precedence

Abstract

An electrochemical gas sensor includes additional gas diffusion electrodes incorporated to carry out one or more diagnostic functions while the sensor is responding to a target gas. Members of a plurality of sensing and diagnostic electrodes can be switched by associated control circuits to intermittently sense a target gas while others intermittently sense a different gas. The diagnostic electrodes are in direct communication with the target gas that is entering the cell.

Claims

1. A gas sensor comprising:

a housing defining an ambient gas port and a diffusion cavity, wherein the ambient gas port comprises a diffusion barrier;

a first sensing electrode configured to sense a target gas, wherein the target gas is not oxygen; and

a second sensing electrode configured to sense oxygen gas,

wherein the ambient gas port is the only entrance into the housing and the diffusion cavity,

wherein the diffusion cavity is located in a gaseous diffusion path between the ambient gas port and both the first sensing electrode and the second sensing electrode,

wherein the first sensing electrode and the second sensing electrode are in gaseous contact with the diffusion cavity,

wherein a flexible substrate carries the first sensing electrode and the second sensing electrode,

wherein the first sensing electrode and the second sensing electrode are co-planar,

wherein the first sensing electrode and the second sensing electrode are distributed symmetrically about an axis passing through the ambient gas port, and

wherein a plane of the first sensing electrode and the second sensing electrode is perpendicular to the axis passing through the ambient gas port.

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

control circuits electrically coupled to the first sensing electrode and the second sensing electrode.

3. The gas sensor as in claim 1, wherein the first sensing electrode and the second sensing electrode are each formed with one of a cylindrical shape, or an annular shape.

4. The gas sensor as in claim 1, wherein the first sensing electrode comprises a plurality of first electrodes or the second sensing electrode comprises a plurality of second electrodes.

5. The gas sensor as in claim 4, further comprising:

control circuits coupled to the first sensing electrode and the second sensing electrode, wherein the control circuits are configured to cause the first sensing electrode to sense the target gas intermittently, and wherein the control circuits are further configured to cause the second sensing electrode to sense oxygen gas intermittently.

6. The gas sensor as in claim 5, wherein the control circuits are further configured to switch at least one of the first sensing electrode or the second sensing electrode from an active status to an inactive status.

7. The gas sensor as in claim 5, wherein the first sensing electrode and the second sensing electrode are formed with substantially the same shape.

8. The gas sensor as in claim 5, wherein the first sensing electrode and the second sensing electrode each have a surface area of a common size.

9. A gas sensor comprising:

a housing that defines an ambient gas port and an internal gas diffusion region for a target gas and oxygen gas;

a plurality of gas permeable sensing electrodes, carried by a flexible substrate, adjacent to the internal gas diffusion region, wherein the plurality of gas permeable sensing electrodes are in direct contact with the tar gas and the oxygen gas; and

control circuits electrically coupled to the plurality of gas permeable sensing electrodes,

wherein the ambient gas port is only the entrance to the internal gas diffusion region,

wherein the internal gas diffusion region is located between the ambient gas port and the plurality of gas permeable sensing electrodes, and

wherein the control circuits are configured to cause at least one electrode of the plurality of gas permeable sensing electrodes to intermittently sense the target gas and to cause at least one electrode of the plurality of gas permeable sensing electrodes to intermittently sense the oxygen gas.

10. The gas sensor as in claim 9, wherein each of the plurality of gas diffusion sensing electrodes has a same shape.

11. The gas sensor as in claim 10, wherein each of the plurality of gas diffusion sensing electrodes surround a common line, wherein the common line extends perpendicular to a plane of the flexible substrate and asses through the ambient gas port.

12. The gas sensor as in claim 11, wherein the control circuits are configured to select at least one electrode to sense the target gas for a first time interval and at least a second electrode to sense the target gas for a second time interval, and wherein the control circuits are further configured to select a third electrode to sense the oxygen gas for a first diagnostic time interval and a fourth electrode to sense the oxygen gas for a second diagnostic time interval.

13. The gas sensor as in claim 9, wherein the control circuits are configured to use a selected electrode for sensing the target gas during one time interval and for sensing the oxygen gas during another time interval.

14. A gas sensor comprising:

a housing defining an ambient gas port and a diffusion cavity;

a diffusion barrier disposed between the gas port and the diffusion cavity;

a first sensing electrode configured to sense a target gas, wherein the target gas is not oxygen;

a second sensing electrode configured to sense oxygen; and

a counter electrode separated from the first sensing electrode and the second sensing electrode by a separator,

wherein the first sensing electrode and the second sensing electrode are in gaseous contact with the diffusion cavity,

wherein the first sensing electrode and the second sensing electrode are co-planar, and

wherein the first sensing electrode and the second sensing electrode are distributed symmetrically about an axis passing through the ambient gas port.

15. The gas sensor of claim 14, wherein the ambient gas port is the only entrance into the housing and the diffusion cavity.

16. The gas sensor of claim 15, wherein the diffusion cavity is located in a gaseous diffusion path between the ambient gas port and both the first electrode and the second electrode.

17. The gas sensor of claim 14, wherein a plane of the first electrode and the second electrode is perpendicular to the axis passing through the ambient gas port.

18. The gas sensor of claim 14, wherein the first sensing electrode and the second sensing electrode comprise gas diffusion electrodes.