Laminated membranes for diffusion limited gas sensors resistant to pressure variations

• US 20060032742A1
• Filed: 08/16/2004
• Published: 02/16/2006
• Est. Priority Date: 08/16/2004
• Status: Active Grant

• Current Assignee: General Electric Company
• Original Assignee: General Electric Company
• Inventors: Babes-Dornea, Elena, Grincourt, Yves, Beauchemin, Claude
• Granted Patent: US 7,582,196 B2
• Time in Patent Office: Days
• US Class Current: 204/400
• CPC Class Codes: G01N 27/4045 for gases other than oxygen
• CPC Class Codes: G01N 33/2841 gas in oil, e.g. hydrogen in insulating oil
• CPC Class Codes: H01M 8/04089 of gaseous reactants

Abstract

A micro fuel cell sensor having laminated gas permeable membrane. The sensor comprises a housing, first and second gas diffusing electrodes spaced from one another, a fuel-cell spacer having an acidic electrolyte disposed between said first and second electrodes, and two gas permeable membranes. The first gas permeable membrane comprises a polymer laminated on a metal substrate, wherein the substrate comprises pores that have dimensions at least less than one-half the thickness of the polymer film.

Claims

1. A micro-fuel cell sensor for measuring in fluid streams, the sensor comprising:

a housing;

a sensing element comprising first and second gas diffusing electrodes spaced from one another, said sensing element disposed in said housing;

a fuel-cell spacer having an acidic electrolyte disposed between said first and second electrodes;

a gas permeable membrane separating said first electrode from the oil with dissolved gas and enabling gas dissolved in oil to diffuse therethrough, said first membrane being spaced from said first electrode enabling gas diffused through said first membrane to contact said first electrode;

a second gas permeable membrane separating said second electrode from atmospheric air and defining a second cavity therewith isolated from said first cavity.

2. The sensor of claim 1, wherein said first and second electrodes are identical and comprise at least one of Platinum on carbon, Gold, Palladium, Palladium-platinum, Ruthenium, Iridium, Osmium, Rhodium, or Tantalum.

3. The sensor of claim 1, wherein the acidic electrolyte interconnecting said first and second electrodes facilitate the electrochemical oxidation of a dissolved gas at said first electrode and electrochemical reduction at said second electrode.

4. The sensor of claim 3, wherein the electrochemical oxidation at said first electrode of a gas, wherein said gas comprises at least one of hydrogen, carbon monoxide, acetylene, ethylene, methane, and ethane and electrochemical reduction at said second electrode, wherein said gas at second electrode comprises oxygen from the ambient air.

5. The sensor of claim 1, wherein the first gas permeable membrane comprises a polymer laminated on a porous metal disc.

6. The sensor of claim 5, wherein the first gas permeable membrane is impervious to oil.

7. The sensor of claim 5, wherein the first gas permeable membrane is vacuum resistant.

8. The sensor of claim 5, wherein the gas permeation rate through the laminated membrane is less than the rate of the electrochemical gas sensing reaction occurring in the sensor.

9. The sensor of claim 5, wherein the polymer comprises at least one of Polytetrafluoroethylene, Perfluorinated Ethylene-Propylene Copolymer, Perfluoroalkoxy Polytetrafluoroethylene, Polyvinylidene Fluoride, Polyvinyl Chloride, Polyimide, Polyethylene, Polyether Ester Ketone, Polycarbonate and Polyurethane.

10. The sensor of claim 5, wherein the polymer has a thickness in a range from about 25 micron (1 mil) to about 250 micron (10 mil).

11. The sensor of claim 5, wherein the metal disc supports the polymer film under positive and negative pressure.

12. The sensor of claim 11, wherein the metal disc comprises at least one of stainless steel, high nickel and nickel-copper alloys, bronze, and titanium.

13. The sensor of claim 11, wherein the metal disc comprises pores.

14. The sensor of claim 11, wherein the dimension of the pores of the metal disc is less than or equal to about one-half of the polymer film thickness.

15. The sensor of claim 11, wherein the dimension of the pores of the metal disc are much larger than the gas molecules to be analyzed by the sensor.

16. The sensor of claim 1, wherein the second gas permeable membrane comprises a polymer.

17. An apparatus for measuring dissolved gasses in oil, the apparatus comprising:

a housing;

a micro-fuel cell sensor disposed in said housing;

a cover member;

said sensor comprising;

a sensing element comprising first and second gas diffusing electrodes spaced from one another, said sensing element disposed in said housing;

a fuel-cell spacer having an acidic electrolyte disposed between said first and second electrodes;

a first gas permeable membrane separating said first electrode from the oil with dissolved gas and enabling gas dissolved in oil to diffuse therethrough, said first membrane being spaced from said first electrode enabling gas diffused through said first membrane to contact said first electrode;

a second gas permeable membrane separating said second electrode from atmospheric air and defining a second cavity therewith isolated from said first cavity.

18. The sensor of claim 17, wherein said cover member further comprises:

a connector for providing an electrical connection to said sensor; and

a third gas permeable membrane disposed in one of said cover member and said housing for receiving atmospheric air.

19. In a sensor having a housing, a sensing element comprising first and second gas diffusing electrodes spaced from one another, said sensing element disposed in said housing and comprising;

a fuel-cell spacer having an acidic electrolyte disposed between said first and second electrodes;

wherein said electrodes comprise platinum on carbon;

a first gas permeable membrane separating said first electrode from the oil with dissolved gas and enabling gas dissolved in oil to diffuse therethrough, said first membrane being spaced from said first electrode enabling gas diffused through said first membrane to contact said first electrode;

wherein said gas permeable membrane is impervious to oil; and

further wherein the gas permeation rate through the laminated membrane is less than the rate of the electrochemical gas sensing reaction occurring in the sensor;

said gas permeable membrane comprising;

a polymer laminated on a metal disc;

vacuum resistant;

wherein the polymer comprises at least one of Polytetrafluoroethylene, Perfluorinated Ethylene-Propylene Copolymer, Perfluoroalkoxy Polytetrafluoroethylene, Polyvinylidene fluoride, Polyvinyl Chloride, Polyimide, Polyethylene, Polyether Ester Ketone, Polycarbonate and Polyurethane;

and further the polymer has a thickness in a range from about 25 micron (1 mil) to about 250 micron (10 mil);

a porous metal disc;

the metal disc supports the polymer film under positive and negative pressure;

the metal disc comprises pores;

the diameter of the pores of the metal disc are less than or equal to about one-half of the polymer thickness; and

further wherein the dimension of the pores of the metal disc are much larger than the gas molecules to be analyzed by the sensor.