Electrochemical cell

• US 4,187,162 A
• Filed: 06/26/1978
• Issued: 02/05/1980
• Est. Priority Date: 06/26/1978
• Status: Expired due to Term

• Current Assignee: Rosemount Incorporated (Emerson Electric Company)
• Original Assignee: Rosemount Incorporated (Emerson Electric Company)
• Inventors: Dageforde, Allen F.
• Primary Examiner(s): Williams, Howard S.
• Application Number:
  US05/918,856
• Time in Patent Office: 589 Days
• Field of Search: 204/195 P, 204/1 P
• US Class Current: 204/415
• CPC Class Codes: G01N 27/28 Electrolytic cell components
• 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 is directed to certain modifications to sensor cells to minimize electrolyte dilution or loss and to reduce electrical noise. These objectives are attained by designing and constructing the cell in such a manner as to force the electrolyte to communicate between the anode and cathode by diffusion through a porous plug which is placed adjacent the cathode and in contact with the required porous membrane.

Claims

1. A cell for electrochemical analysis of a constituent in a sample comprising:

an electrically nonconductive body having an electrolytic reservoir therein, said electrolytic reservoir containing an electrolyte;

a pair of spaced electrodes, a first of said electrodes being positioned within said reservoir in contact with the electrolyte filling said reservoir;

an opening defined in said body to provide a passageway between said reservoir and the exterior of said body;

means closing said opening including a porous material in contact with the electrolyte in the reservoir and providing a path for electrolyte diffusion therethrough;

said porous material comprising the sole path for transfer of electrolyte from the reservoir to the exterior of the body;

means mounting a second of said electrodes on the exterior of the reservoir within the perimeter of said opening adjacent said porous material and being electrically coupled with the first electrode through electrolyte carried through the porous material;

a thin, flexible polymeric membrane permeable to both said constituent and said electrolyte overlying said porous material and said second electrode; and

cover means overlying said membrane and providing an opening through which the constituent contacts the membrane, the interchange of the constituent and the electrolyte thereby being restricted by said porous material.

2. The electrochemical cell of claim 1 and a generally cylindrical nonelectrically conductive member substantially centered within said opening, said porous material surrounding said cylindrical member, said second electrode being mounted to the end of said cylindrical member on the exterior of said body.

3. The electrochemical cell as specified in claim 2 wherein said porous material comprises an annular ring surrounding said cylindrical plug, and wherein said cover has a second opening therein, said second opening being of slightly larger diameter than said cylindrical member to limit the area of the porous material exposed to the constituent.

4. The cell according to claim 1 wherein the constituent comprises a halogen in an aqueous medium.

5. A cell according to claim 1, wherein the porous material is composed of a member selected from the group consisting of porous wood, poly olefins, and polycarbonates.