ELECTROCHEMICAL ANALYZER

• US 3,847,777 A
• Filed: 05/08/1972
• Issued: 11/12/1974
• Est. Priority Date: 05/08/1972
• Status: Expired due to Term

• Current Assignee: Il Holding SpA (Werfen SA)
• Original Assignee: Ihsan A. Haddad, William M. Krebs
• Inventors: Haddad, Ihsan A., Krebs, William M.
• Primary Examiner(s): Tung, T.
• Application Number:
  US05/251,287
• Time in Patent Office: 918 Days
• Field of Search: 204/1T,195P
• US Class Current: 204/415
• CPC Class Codes: G01N 27/49 Systems involving the determination of the current at a single specific value, or small range of values, of applied voltage for producing selective measurement of one or more particular ionic species

Abstract

An electrochemical analyzer includes a cathode electrode, an anode electrode, and electrolyte in the space between them. A selectively permeable membrane is disposed over the cathode electrode and in turn is covered by a porous hydrophobic membrane. The porous membrane has a substantially greater area than that of the cathode, and allows substantially unimpeded gaseous flow through it in both the lateral and longitudinal directions.

Claims

1. AN ELECTROCHEMICAL ANALYZER COMPRISING:

TWO ELECTRODES SPACED APART FROM EACH OTHER, AN ELECTROLYTE IN THE SPACE BETWEEN SAID ELECTRODES, AND A COMPOSITE MEMBRANE STRUCTURE OVER THE SURFACE OF ONE OF SAID ELECTRODES, SAID COMPOSITE STRUCTURE HAVING A SURFACE AREA SUBSTANTIALLY LARGER THAN THE AREA OF SAID SURFACE OF SAID ELECTRODE AND COMPRISING A SELECTIVELY PERMEABLE LAYER SEPARATED FROM SAID ELECTRODE SURFACE BY A THIN LAYER OF SAID ELECTROLYTE, AND A LAYER OF HYDROPHOBIC MATERIAL IN OVERLYING ENGAGEMENT WITH SAID SELECTIVELY PERMEABLE LAYER, SAID LAYER OF HYDROPHOBIC MATERIAL HAVING POROSITY THAT ALLOWS SUBSTANTIALLY UNIMPED GASEOUS FLOW IN BOTH THE LATERAL AND LONGITUDINAL DIRECTIONS.

2. The analyzer of claim 1 wherein the internal structure of said layer of hydrophobic material comprises a matrix of open channels for gaseous transfer in both the lateral and longitudinal directions.

3. The analyzer of claim 1 wherein said layer of hydrophobic material is composed of a multiplicity of interengaged fibers.

4. The analyzer of claim 1 wherein said layer of hydrophobic material has a pore size greater than three microns and a pore volume of more than fifty percent.

5. The analyzer of claim 1 wherein said layer of hydrophobic material has a pore size in the range of three to 60 microns and a pore volume of more than 70 percent.

6. The analyzer of claim 1 wherein said layer of hydrophobic material is composed of polyfluorocarbon fibers.

7. The analyzer of claim 1 wherein said layer of hydrophobic material has a surface area at least 10 times as large as the area of said surface of said one electrode.

8. The analyzer of claim 1 wherein said layer of hydrophobic material comprises a matrix of polyfluorocarbon fibers and has a pore volume of at least 50 percent and its pores have a pore size of at least 3 microns.

9. An electrochemical analysis cell for sensing a gaseous constituent of a test medium comprising:

a housing defining an electrolyte chamber, said housing having an aperture in a wall thereof, a selectively permeable membrane attached to said housing and covering said aperture, an electrolyte substance within said chamber, a cathodic electrode supported within said chamber and separated from said membrane by a thin layer of said electrolyte substance, an anodic electrode supported within said chamber and spaced apart from the cathodic electrode, a porous hydrophobic membrane attached to said housing and in overlying engagement with said selectively permeable membrane, said porous hydrophobic membrane having sufficient porosity for allowing substantially unimpeded gaseous flow in both the lateral and longitudinal directions, and having a surface area substantially larger than the area of said cathodic electrode.

10. The analyzer of claim 9 wherein the internal geometry of said porous hydrophobic membrane includes a multiplicity of open channels permitting flow of a constituent of the medium to be analyzed in both lateral and longitudinal directions at a rate comparable to the rate of flow of said constituent in said medium.

11. The analyzer of claim 9 wherein said porous hydrophobic membrane is composed of interengaged fibers.

12. The analyzer of claim 9 wherein said porous hydrophobic membrane has a pore volume of more than fifty percent.

13. The analyzer of claim 9 wherein said porous hydrophobic membrane has a pore size of at least three microns and a pore volume of more than seventy percent.

14. The analyzer of claim 9 wherein said porous hydrophobic membrane is composed of polyfluorocarbon fibers arranged to define a multiplicity of open channels permitting flow of a constituent of the medium to be analyzed in both lateral and longitudinal directions at substantially the same rate of flow as the rate of flow of said constituent in said medium, and to have a pore size of at least three microns.

15. The analyzer of claim 14 wherein said porous hydrophobic membrane has a surface area at least 10 times the area of said cathodic electrode.