ELECTROCHEMICAL SENSOR HAVING A MEDIATOR COMPOUND WITH A SOLID

• US 20080035493A1
• Filed: 02/22/2007
• Published: 02/14/2008
• Est. Priority Date: 03/30/2006
• Status: Active Grant

• Current Assignee: Dragerwerk AG & Company KGaA (FPS Vermögensverwaltung GmbH)
• Original Assignee: Dragerwerk AG
• Inventors: SOMMER, Sabrina, METT, Frank, KIESELE, Herbert
• Granted Patent: US 8,268,161 B2
• Time in Patent Office: Days
• US Class Current: 205/786.5
• 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 is provided especially for gases. The electrochemical sensor has a mediator compound, which is both dissolved in an electrolyte (9) in a saturated form and is present as an excess solid (10) in the electrolyte (9).

Claims

1. An electrochemical gas sensor for detecting an analyte, the electrochemical gas sensor comprising:

a housing defining an electrolyte space;

a measuring electrode comprising a carbon-containing material, said measuring electrode being disposed in said electrolyte space;

an auxiliary electrode disposed in said electrolyte space;

a liquid electrolyte disposed in said electrolyte space; and

an analyte-selective mediator, said analyte-selective mediator being provided in a saturated form in said electrolyte and being present as an excess solid in the electrolyte space.

2. An electrochemical gas sensor in accordance with claim 1, wherein said measuring electrode comprises at least one of graphite, diamond-like carbon (DLC), carbon nanotubes (CNT) or boron-doped diamond (BDD).

3. An electrochemical gas sensor in accordance with claim 1, further comprising a reference electrode comprising at least one of graphite, diamond-like carbon (DLC) or boron-doped diamond (BDD) or carbon nanotubes.

4. An electrochemical gas sensor in accordance with claim 1, wherein said mediator comprises a mediator compound that is a transition metal salt of an acid compound, said acid compound containing at least two acid groups or at least one acid group and two hydroxyl groups.

5. An electrochemical gas sensor in accordance with claim 4, wherein said acid compound is a carboxylic acid.

6. An electrochemical gas sensor in accordance with claim 5, wherein said carboxylic acid is an aromatic carboxylic acid with two or three carboxyl groups, especially phthalic acid, isophthalic acid or terephthalic acid.

7. An electrochemical gas sensor in accordance with claim 4, wherein the acid compound is an aliphatic polycarboxylic acid, especially citric acid.

8. An electrochemical gas sensor in accordance with claim 4, wherein the acid compound is gluconic acid.

9. An electrochemical gas sensor in accordance with claim 4, wherein the acid compound is a boric acid.

10. An electrochemical gas sensor in accordance with claim 4, wherein said liquid electrolyte is a solution containing alkali or alkaline earth metal salts, preferably LiCl.

11. An electrochemical gas sensor in accordance with claim 4, wherein water or organic solvents including ethylene and/or propylene carbonate, are used as a solvent.

12. An electrochemical gas sensor in accordance with claim 4, wherein the transition metal salt is a copper salt or a Cu²⁺ salt.

13. An electrochemical gas sensor in accordance with claim 12, wherein the Cu²⁺ salt is CuCl₂ and the concentration of CuCl₂ in a 2-10-molar LiCl solution is between 0.2 mol and 1.0 mol.

14. An electrochemical gas sensor in accordance with claim 12, wherein the Cu²⁺ salt is CuCl₂ and the concentration of CuCl₂ in a 2-10-molar LiCl solution is about 0.5 mol.

15. An electrochemical gas sensor in accordance with claim 4, wherein the transition metal salt is an iron salt or an Fe³⁺ salt.

16. Electrochemical gas sensor in accordance with claim 1, further comprising a gas-permeable membrane, said housing having an opening with said gas-permeable membrane, wherein an analyte substance enters the area of said measuring electrode via said gas-permeable membrane.

17. An electrochemical gas sensor in accordance with claim 1, further comprising a reference electrode.

18. An electrochemical gas sensor in accordance with claim 1, further comprising a protective electrode arranged behind said measuring electrode.

19. A process of electrochemical gas sensing, the process comprising:

providing a housing defining an electrolyte space;

providing a measuring electrode comprising a carbon-containing material, said measuring electrode being disposed in said electrolyte space;

providing an auxiliary electrode disposed in said electrolyte space;

providing a liquid electrolyte disposed in said electrolyte space;

providing an analyte-selective mediator;

providing said analyte-selective mediator in a saturated form in said electrolyte; and

providing said analyte-selective mediator as an excess solid in the electrolyte space.

20. A process of electrochemical gas sensing according to claim 19, further comprising:

determining SO₂ concentration in a gas using the measuring electrode, wherein said electrolyte is or contains a chloride.

21. A process of electrochemical gas sensing according to claim 19, further comprising:

determining H₂S concentration in a gas using the measuring electrode, wherein said electrolyte is or contains a chloride.