Method of preparing an electrochemical planar metal/metal oxide electrode

• US 5,702,575 A
• Filed: 11/01/1995
• Issued: 12/30/1997
• Est. Priority Date: 01/27/1995
• Status: Expired due to Term

• Current Assignee: Siemens Healthcare Diagnostics Incorporated (Siemens AG)
• Original Assignee: Chiron Diagnostics Corp (Bayer AG)
• Inventors: Benco, John S., Foos, Joseph S.
• Primary Examiner(s): Bell, Bruce F.
• Application Number:
  US08/551,596
• Time in Patent Office: 790 Days
• Field of Search: 204/412, 204/435, 204/280, 204/291, 204/292, 423/22, 423/23, 423/35, 423/84
• US Class Current: 204/292
• CPC Class Codes: G01N 27/333 Ion-selective electrodes or membranes glass electrodes G01N27/36

Abstract

An improved active electrode for use in planar sensors has been discovered, the electrode prepared by a process comprising combining a base component with a metal paste and heating the paste in the presence of air for a time sufficient to oxidize a portion of the electrode to produce the metal/metal oxide electrode. The electrodes may be incorporated into various planar sensor formats, particularly pH and CO₂ sensors.

Claims

1. A method for preparing a planar active metal/metal oxide electrode, said method comprising combining a base component consisting essentially of a salt with a metal paste to form a metal paste mixture, heating the metal paste mixture in the presence of air for a time sufficient to cause said heat to oxidize a portion of the mixture to form said metal/metal oxide electrode.

2. A method according to claim 1 wherein said salt is non-hydroscopic.

3. A method according to claim 1 wherein said metal paste is a palladium paste.

4. A method according to claim 3 wherein said base component is NaHCO₃.

5. A method according to claim 1 wherein said heating occurs at a temperature of from about 450°

C. to 600°

C. for a period of from about 1 minute to about 30 minutes.

6. A method according to claim 5 wherein said metal is a noble metal selected from the group consisting of palladium, rhodium, ruthenium, osmium, iridium, platinum, tin, antimony, bismuth, alloys thereof, and mixtures thereof, and said base component is a salt selected form the group consisting of alkali metal salts and alkali earth metal salts.

7. A method according to claim 6 wherein said metal paste is a palladium paste, and said base component is NaHCO₃.

8. A method according to claim 7 wherein heating is at a temperature of 525°

C. to 575°

C. for a period of about 5 minutes to 15 minutes and said salt is present in an amount ranging from about 0.1 wt. % to about 50 wt. %, based on the total weight of the mixture prior to heating.

9. A method according to claim 8 wherein said salt present in an amount of about 16 wt. %.