Measuring sensor for detecting gaseous components

• US 5,202,011 A
• Filed: 06/07/1991
• Issued: 04/13/1993
• Est. Priority Date: 06/09/1990
• Status: Expired due to Fees

• Current Assignee: Dragerwerk AG
• Original Assignee: Dragerwerk AG
• Inventors: Sohege, Jurgen, Kiesele, Herbert
• Primary Examiner(s): Niebling, John
• Assistant Examiner(s): Bell, Bruce F.
• Application Number:
  US07/711,802
• Time in Patent Office: 676 Days
• Field of Search: 204/415, 204/409, 204/410, 204/424, 204/153.1
• US Class Current: 204/415
• 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 invention is directed to a measuring sensor for detecting gaseous components which operates in the diffusion limit current region. The measuring sensor includes a support body and has an electrolyte chamber partitioned by a diffusion membrane from the ambient containing the gaseous components. The measuring electrode of the measuring sensor is improved so that a simpler manipulation for covering the electrolyte chamber with a membrane is possible without endangering the mechanical stability of the membrane. During operation, the detection operation is intended to take place completely at that electrode surface which is in direct electrochemical exchange communication with the electrolyte supply. For this purpose, the coating is configured as an adherence joiner to the support body so that it forms an impermeable adherence region in the lateral direction between coating and support body. A process for producing the measuring electrode is characterized in that the coating is adheringly applied to a front face of the support body which forms a closed surface. Thereafter, a membrane layer is applied to the coating and a break through for communicating with the electrolyte chamber is formed in the support body by removing a portion of the support body starting from a rear face thereof lying opposite the front face. The break through is formed by removing the portion of the support body through to the coating. In the completed measuring sensor, this permits electrolyte from the electrolyte chamber to penetrate through the break through to the coating.

Claims

1. A method of making a measuring electrode structure for a measuring sensor for detecting gaseous components in the ambient, the measuring sensor including an electrolyte chamber for accommodating an electrolyte therein, the method comprising the steps of:

applying a permeable, electrically-conductive coating to a closed front face of a support body so as to form an adhering interface therewith, said coating defining a measuring electrode having an electrochemically active surface at said interface;

applying a membrane layer directly to said coating so as to form an adhering connection thereto, said membrane being permeable to the gaseous components and impermeable to the electrolyte;

forming a break through in said support body by removing a portion thereof starting from a rear face of said support body and continuing to said front face thereby causing said break through to extend to said active surface, said rear face being opposite said front face; and

,

said break through being formed by removing said portion of said support body through to said coating so as to permit the electrolyte from the electrolyte chamber to penetrate through said break through to said coating and said electrochemically active surface thereof.

2. The method of claim 1, said break through being formed in said support body by etching.

3. The method of claim 1, said coating being formed by a galvanic precipitation.

4. The method of claim 2, said support body being made of a first metal;

said coating being made of a second metal; and

, said second metal being more precious than said first metal.

5. The method of claim 1, said membrane layer being applied to said coating utilizing a polymerization process.

6. The method of claim 1, said break through being defined by a plurality of channels.

7. A method of making a measuring electrode structure for a measuring sensor for detecting gaseous components in the ambient, the measuring sensor including an electrolyte chamber for accommodating an electrolyte therein, the method comprising the steps of:

forming a recess in a support body by removing a portion thereof starting from a rear face of said support body, said support body having a closed front face opposite said rear face;

terminating the formation of said recess so as to leave a supporting layer between the base of said recess and said closed front face which is adequately stable for the later application of a permeable electrically-conductive coating and a membrane layer to said closed front surface;

applying said coating to said closed front face of said support body so as to form an adhering interface therewith;

applying said membrane layer to said coating so as to form an adhering connection thereto, said membrane being permeable to the gaseous components and impermeable to the electrolyte;

resuming the formation of said recess in said support body by removing said supporting layer so as to cause said recess to be a clear break through extending from said rear face to said coating so as to permit the electrolyte from the electrolyte chamber to penetrate through said break through to said coating.

8. The method of claim 7, said recess being formed in said support body by etching.

9. The method of claim 7, said coating being formed by a galvanic precipitation.

10. The method of claim 9, said support body being made of a first metal;

said coating being made of a second metal; and

, said second metal being more precious than said first metal.

11. The method of claim 7, said membrane layer being applied to said coating utilizing a polymerization process.

12. The method of claim 7, said break through being defined by a plurality of channels.