Reference electrode

• US 5,071,537 A
• Filed: 05/08/1989
• Issued: 12/10/1991
• Est. Priority Date: 07/10/1986
• Status: Expired due to Term

• Current Assignee: Terumo Kabushiki Kaisha
• Original Assignee: Terumo Kabushiki Kaisha
• Inventors: Yamaguchi, Shuichiro, Shimomura, Takeshi, Ushizawa, Norihiko
• Primary Examiner(s): Tung, T.
• Application Number:
  US07/298,744
• Time in Patent Office: 946 Days
• Field of Search: 204/414, 204/435
• US Class Current: 204/414
• CPC Class Codes: G01N 27/301 Reference electrodes

Abstract

A miniature, solid-state long-life reference electrode in which the amount of outflow of an internal electrolyte containing a halogen ion is reduced includes a conductor on the periphery of which is formed a sintered body consisting of a silver halide and silver oxide, a water-containing gel enveloping the conductor and including a halogen ion electrolyte, and a hollow tubular body closed by a liquid-junction portion comprising a porous ceramic, or by a partitioning wall having an ion permeable portion of a predetermined diffusion coefficient and volume. In another embodiment, the tubular body of the reference electrode is partitioned by a partitioning wall having an ion permeable portion of a predetermined diffusion coefficient and volume.

Claims

1. A reference electrode comprising:

an electrical conductor consisting of platinum or silver;

a sintered body on the electrical conductor formed of a mixture of silver halide and silver oxide;

a water-containing gel enveloping said sintered body and containing a halogen ion electrolyte;

a hollow tubular body accommodating said water-containing gel and having one end closed by a first liquid-junction portion and its other end liquid-tightly sealed by a plug; and

a conductor wire connected to the electrical conductor and extended to pass through the plug liquid tightly.

2. The reference electrode according to claim 1, wherein said first liquid-junction portion comprises a porous ceramic including a silicate and carbon.

3. The reference electrode according to claim 1, wherein said water-containing gel is selected from the group consisting of polyvinyl alcohol, polyacrylic amide, agar-agar, gelatin, mannon and starch.

4. The reference electrode according to claim 1, wherein said halogen ion is supplied to said water-containing gel by sodium chloride.

5. The reference electrode according to claim 1, wherein said first liquid-junction portion comprises an ion impermeable wall penetrated by an ion permeable portion permeable to said halogen ion and having a pre-determined diffusion coefficient and volume.

6. The reference electrode according to claim 5, wherein said water-containing gel is selected from the group consisting of polyvinyl alcohol, polyacrylic amide, agar-agar, gelatin, mannon and starch.

7. The reference electrode according to claim 5, wherein said halogen ion is supplied to said water-containing gel by sodium chloride.

8. The reference electrode according to claim 5, wherein the diffusion coefficient of said ion permeable portion ranges from 10^-7 to 10^-10 cm² /sec and the volume thereof ranges from 0.01 to 6 mm³.

9. The reference electrode according to claim 5, wherein said ion permeable portion comprises an ion exchange resin layer.

10. The reference electrode according to claim 5, wherein said ion permeable portion comprises an anion exchange resin layer and a cation-exchange resin layer.

11. The reference electrode according to claim 5, wherein said ion permeable portion comprises a hollow fiber filled with the water-containing gel containing the halogen ion electrolyte.

12. The reference electrode according to claim 11, wherein said hollow fiber comprises an ion permeable hydrophilic polymer or an ion permeable hydrophobic polymer.

13. The reference electrode according to claim 5, wherein said water-containing gel is a natural high polymer.

14. The reference electrode according to claim 1, further comprising a second liquid-junction portion partitioning said water-containing gel into at least two portions.

15. The reference electrode according to claim 14, wherein at least one of said first and second liquid-junction portions comprises an ion impermeable wall penetrated by an ion permeable portion permeable to said halogen ion and having a predetermined diffusion coefficient and volume, and the diffusion coefficient of said ion permeable portion ranges from 10^-7 to 10^-10 cm² /sec and the volume thereof ranges from 0.01 to 6 mm³.

16. The reference electrode according to claim 15, wherein said ion permeable portion comprises an ion exchange resin layer.

17. The reference electrode according to claim 15, wherein said ion permeable portion comprises an anion exchange resin layer and a cation-exchange resin layer.

18. The reference electrode according to claim 15, wherein said ion permeable portion comprises a hollow fiber filled with the water-containing gel containing the halogen ion electrolyte.

19. The reference electrode according to claim 18, wherein said hollow fiber comprises an ion permeable hydrophilic polymer or an ion permeable hydrophobic polymer.

20. The reference electrode according to claim 14, wherein at least one of said first and second liquid-junction portions comprises a porous ceramic including a silicate and carbon.

21. The reference electrode according to claim 1, wherein said water-containing gel is a natural high polymer.