Electrochemical sensor

• US 5,667,653 A
• Filed: 03/15/1996
• Issued: 09/16/1997
• Est. Priority Date: 03/15/1996
• Status: Expired due to Term

• Current Assignee: Mine Safety Appliances Company (MSA Safety, Inc.)
• Original Assignee: Mine Safety Appliances Company (MSA Safety, Inc.)
• Inventors: Schneider, Alan A., Scheffler, Towner B., Davis, Brian K.
• Primary Examiner(s): TUNG, TA HSUNG
• Application Number:
  US08/616,689
• Time in Patent Office: 550 Days
• Field of Search: 204/400, 204/415, 204/431, 204/432, 429/203, 429/204, 429/205, 429/199
• US Class Current: 204/431
• CPC Class Codes: G01N 27/404 Cells with anode, cathode and cell electrolyte on the same side of a permeable membrane which separates them from the sample fluid , e.g. Clark-type oxygen sensors
• CPC Class Codes: G01N 27/4045 for gases other than oxygen

Abstract

The present invention provides a low-cost alternative to currently available electrochemical sensors. In general, the present invention provides an electrochemical sensor for the detection of an analyte comprising a first metallic housing member and a second metallic housing member. The first metallic housing member and the second metallic housing member are brought together in sealed connection to create a sealed enclosure therebetween. Contained within the enclosure are a first electrode, at which the analyte reacts, and a second electrode, at which a reaction complimentary to the reaction of the analyte at the first electrode takes place. An acidic electrolyte is also contained within the enclosure of the first metallic housing member and the second metallic housing member.

Claims

1. An electrochemical sensor comprising:

a metallic housing, the metallic housing including an inlet port therein to allow an analyte to enter the housing, the electrochemical sensor further comprising within the metallic housing at least a first electrode and a second electrode, electrical conductivity being maintained between the first electrode and the second electrode via an acidic electrolyte system having a pH less than approximately 3.0 present within the metallic housing and contacting at least a portion of the metallic housing, the first electrode comprising an electrochemically active material suitable to cause a reaction of the analyte to detect a concentration of the analyte, the electrochemical sensor further comprising circuitry adapted to measure an output signal resulting from reaction of the analyte at the first electrode during operation of the electrochemical sensor.

2. The electrochemical sensor of claim 1 wherein the metal used to form the metallic housing results in a corrosion current no greater than one-half of the output signal resulting from reaction of the analyte during operation of the electrochemical sensor over a detectable concentration range of interest at temperatures less than approximately 50°

C.

3. The electrochemical sensor of claim 2 wherein the metallic housing comprises a first metallic housing member and a second metallic housing member, the first metallic housing member and the second metallic housing member being brought together in connection to form the metallic housing.

4. The electrochemical sensor of claim 3, wherein the connection between the first metallic member and the second metallic member is achieved by placing an electrically insulating member between the first metallic member and the second metallic member, the first metallic member being in electrically conductive connection with the first electrode to function as the electrical contact for the first electrode, and the second metallic member being in electrically conductive connection with the second electrode to function as the electrical contact for the second electrode.

5. The electrochemical sensor of claim 4, wherein the insulating member comprises a plastic material.

6. The electrochemical sensor of claim 2 wherein the acidic electrolyte system has a pH less than approximately 1.0.

7. The electrochemical sensor of claim 2 wherein the acidic electrolyte system is a liquid acid and is at least partially absorbed in a solid support.

8. The electrochemical sensor of claim 7 wherein the solid support is selected from the group consisting of glass fiber and granular SiO₂.

9. The electrochemical sensor of claim 7 wherein the solid support has a percent void volume in the range of approximately 30% to approximately 60%.

10. The electrochemical sensor of claim 9 wherein the ratio of an internal volume of the metallic housing to a void volume of the solid support is in the range of approximately 4 to approximately 12.

11. The electrochemical sensor of claim 7 wherein the metallic housing is fabricated from austenitic stainless steel.

12. The electrochemical sensor of claim 11 wherein the acidic electrolyte system has a pH less than approximately 1.0.

13. The electrochemical sensor of claim 1 wherein the acidic electrolyte system has a pH less than approximately 1.0.

14. The electrochemical sensor of claim 2 wherein the metallic housing is fabricated from austenitic stainless steel.

15. The electrochemical sensor of claim 1 wherein the metallic housing is fabricated from austenitic stainless steel.

16. An electrochemical sensor comprising:

a metallic housing, the metallic housing including an inlet port therein to allow carbon monoxide to enter the housing, the electrochemical sensor further comprising within the metallic housing at least a first electrode, the first electrode comprising an electrochemically active material suitable to cause a reaction of the carbon monoxide to detect a concentration of the carbon monoxide, and a second electrode, electrical conductivity being maintained between the first electrode and the second electrode via an acidic electrolyte system having a pH less than approximately 3.0 present within and contacting at least a portion of the metallic housing.

17. The electrochemical sensor of claim 16 wherein the metal used to form the metallic housing results in a corrosion current no greater than one-half of an output signal current resulting from reaction of the analyte during operation of the sensor over a detectable concentration range of interest at temperatures less than approximately 50°

C.

18. The electrochemical sensor of claim 17 wherein the metallic housing comprises a first metallic housing member and a second metallic housing member, the first metallic housing member and the second metallic housing member being brought together in connection to form the metallic housing.

19. The electrochemical sensor of claim 18, wherein the connection between the first metallic member and the second metallic member is achieved by placing an electrically insulating member between the first metallic member and the second metallic member, the first metallic member being in electrically conductive connection with the first electrode to function as the electrical contact for the first electrode, and the second metallic member being in electrically conductive connection with the second electrode to function as the electrical contact for the second electrode.

20. The electrochemical sensor of claim 19, wherein the insulating member comprises a plastic material.

21. The electrochemical sensor of claim 17 the electrochemical sensor further comprising circuitry adapted to measure the output signal resulting from reaction of the analyte at the first electrode during operation of the electrochemical sensor.

22. The electrochemical sensor of claim 21 wherein the metallic housing is fabricated from austenitic stainless steel.

23. The electrochemical sensor of claim 22 wherein the acidic electrolyte system has a pH less than approximately 1.0.

24. The electrochemical sensor of claim 17 wherein the acidic electrolyte system has a pH less than approximately 1.0.

25. The electrochemical sensor of claim 17 wherein the acidic electrolyte system comprises aqueous sulfuric acid.

26. The electrochemical sensor of claim 17 wherein the first electrode includes an electrochemically active material comprising platinum and the second electrode includes an electrochemically active material comprising platinum.

27. The electrochemical sensor of claim 17 wherein the metallic housing is fabricated from austenitic stainless steel.

28. The electrochemical sensor of claim 16 wherein the metallic housing is fabricated from austenitic stainless steel.