Electrochemical sensor

• US 20060237313A1
• Filed: 11/08/2005
• Published: 10/26/2006
• Est. Priority Date: 12/23/2004
• Status: Active Grant

• Current Assignee: Draeger Safety Incorporated (Dragerwerk AG)
• Original Assignee: Draeger Safety Incorporated (Dragerwerk AG)
• Inventors: Sommer, Sabrina, Kiesele, Herbert, Mett, Frank
• Granted Patent: US 7,615,139 B2
• Time in Patent Office: Days
• US Class Current: 204/412
• 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

Abstract

An electrochemical sensor with at least one measuring electrode (3), at least one auxiliary electrode (7) and at least one reference electrode (5), wherein a protective electrode (6), which ensures at the reference electrode (5) the at least partial shielding of the reference electrode (5) against substances that would lead to a change in the reference potential when reaching the reference electrode (5), is arranged in the vicinity of the reference electrode (5). A highly stable reference potential can be obtained with the present invention.

Claims

1. An electrochemical sensor, comprising:

a measuring electrode;

an auxiliary electrode;

a reference electrode;

a protective electrode, which ensures at said reference electrode the at least partial shielding of said reference electrode against substances that would lead to a change in a reference potential when reaching said reference electrode, is arranged in a vicinity of said reference electrode.

2. An electrochemical sensor in accordance with claim 1, wherein said protective electrode is at a potential that deviates from a potential at which said measuring electrode is maintained by at most +/−

100 mV.

3. An electrochemical sensor in accordance with claim 1, wherein a surface of said reference electrode is partially covered with a material that has a barrier action against substances that would lead to a change in a reference potential when reaching said reference electrode.

4. An electrochemical sensor in accordance with claim 1, wherein said reference electrode is located on a plastic carrier, which seals said reference electrode on at least one side.

5. An electrochemical sensor in accordance with claim 1, wherein said reference electrode is shielded at least partially by an ion exchange membrane.

6. An electrochemical sensor in accordance with claim 1, wherein said reference electrode is surrounded essentially by said protective electrode that is permeable to electrolyte.

7. An electrochemical sensor in accordance with claim 1, wherein said reference electrode is integrated in a stack of layers, which contains alternatingly layers of a material of said reference electrode and layers of a material of said protective electrode, an outer limitation of said stack of layers being formed by layers of the material of said protective electrode.

8. An electrochemical sensor in accordance with claim 1, wherein at least one layer of the material of said protective electrode and at least one layer of the material of said reference electrode are rolled up in a form of a “

Swiss roll”

structure, the outer limitation of said roll structure being formed by a layer of the material of said protective electrode.

9. An electrochemical sensor in accordance with claim 1, wherein the sensor contains an arrangement concentric cylinder electrodes as said measuring electrode, auxiliary electrode, reference electrode and protective electrode.

10. An electrochemical sensor in accordance with claim 1, wherein the sensor is designed as a flat sensor with nearly two-dimensional diffusion paths, said protective electrode being placed such that it blocks the diffusion paths to said reference electrode for substances affecting the reference potential.

11. An electrochemical sensor in accordance with claim 7, wherein at least one layer of nonwoven material, which ensures the flat contact of both electrodes with the electrolyte, is arranged between said protective electrode and said reference electrode.

12. An electrochemical sensor in accordance with claim 1, wherein said reference electrode consists essentially of a catalytically active precious metal.

13. An electrochemical sensor in accordance with claim 1, wherein said reference electrode consists essentially of diamond-like carbon.

14. An electrochemical sensor in accordance with claim 1, wherein said reference electrode consists essentially of doped diamond.

15. An electrochemical sensor in accordance with claim 1, wherein said reference electrode consists essentially of “

carbon nanotubes.”

16. An electrochemical sensor in accordance with claim 1, further comprising a contained mediator material which essentially determines the potential of said reference electrode.

17. An electrochemical sensor in accordance with claim 1, wherein said protective electrode consists essentially of platinum.

18. An electrochemical sensor in accordance with one of the claim 1, wherein said measuring electrode and said reference electrode consist essentially of the same material or materials.

19. An electrochemical sensor, comprising:

a measuring electrode;

a reference electrode; and

a protective electrode arranged adjacent to said reference electrode to at least partially shield said reference electrode against substances that would lead to a change in a reference potential when reaching said reference electrode.

20. An electrochemical sensor in accordance with claim 19, further comprising an auxiliary electrode and an electrolyte, wherein said protective electrode is at a potential that deviates from the potential at which said measuring electrode is maintained by at most +/−

100 mV and wherein the surface of said reference electrode is partially covered with a material that has a barrier action against substances that would lead to a change in the reference potential when reaching said reference electrode.