Miniaturized solid-state reference electrode with self-diagnostic function

• US 6,554,982 B1
• Filed: 07/12/2001
• Issued: 04/29/2003
• Est. Priority Date: 03/25/1999
• Status: Expired due to Fees

• Current Assignee: INFOPIA CO., LTD
• Original Assignee: INFOPIA CO., LTD
• Inventors: Bae, Byeong Woo, Lee, Sung Dong, Nam, Hakhyun, Cha, Geun Sig, Shin, Jae Ho
• Primary Examiner(s): Tung, T.
• Application Number:
  US09/889,032
• Time in Patent Office: 656 Days
• Field of Search: 204/435, 204/414, 204/401, 204/412
• US Class Current: 204/401
• CPC Class Codes: G01N 27/301 Reference electrodes

Abstract

The present invention relates to a reference electrode for a potentiometric electrode system, characterized in that the junction in contact with a sample solution is enlarged and an ion-sensitive membrane containing an ion selective material as a protective membrane for the inner reference solution is employed, which comprises a substrate; a metal layer; an insoluble metal salt layer; an insulating film for insulating the metal layer from an aqueous solution; a hydrogel serving as an inner reference solution; the junction on the hydrogel contacting with a sample solution; the ion-sensitive, protective membrane formed over all surface areas of the hydrogel, except for the junction, to separate the sample solution from the inner reference solution or act as an ion-sensing membrane upon the contamination of the junction, whereby the operational abnormality caused by junction contamination may be easily checked and fast activation may be achieved.

Claims

1. A reference electrode for a potentiostatic electrode system, comprising:

a substrate;

a metal layer;

an insoluble metal salt layer;

an insulating film for insulating the metal layer from a sample solution;

a hydrogel serving as an inner reference solution; and

an ion sensitive, protective membrane containing an ion selective material, the ion sensitive, protective membrane being formed on only a portion of the hydrogel such that at least two portions of the hydrogel are not covered by the ion-sensitive, protective membrane and thereby form a plurality of junctions, the ion-sensitive, protective membrane being arranged to separate the inner reference solution from the sample solution and act as an ion-sensing membrane upon contamination of the junctions.

2. The reference electrode as set forth in claim 1, wherein the substrate is prepared from plastic or ceramic, the metal layer is prepared from a pure metal or an alloy, the insoluble metal salt layer is prepared from a silver halide, the insulating film is prepared from a non-conductive polymer, the hydrogel is prepared from a water-soluble polymer saturated with a salt, and the ion-sensitive, protective membrane is prepared from an ion-selective electrode membrane.

3. The reference electrode as set forth in claim 2, wherein the substrate is made of poly(vinyl chloride) or alumina (Al₂O₃);

the metal layer is made of a metal selected from the group consisting of silver (Ag), platinum (Pt), gold (Au), copper (Cu) and alloys thereof;

the insoluble metal salt layer is made of a silver halide selected from the group consisting of silver chloride (AgCl), silver bromide (AgBr) and silver iodide (AgI);

the insulating film is a ceramic film, a dielectric film or a photosensitive film;

the hydrogel is prepared by dissolving a water-soluble compound selected from the group consisting of polyacrylic acid, METHOCEL®

(methylated cellulose), polyvinylalcohol, (hydroxypropyl)methyl cellulose, polyvinylpyrrolidone, poly(methyl methacrylate), agar and gelatin at 0.5-30 wt % in a saturated solution of KCl, KNO₃, or NH₄NO₃ in water; and

the ion-sensitive, protective membrane is selected from the group consisting of a potassium ion-, a sodium ion-, a calcium ion- and a chloride ion-selective electrode membrane.

4. The reference electrode as set forth in claim 3, wherein the ion-sensitive, protective membrane has a polymer support selected from the group consisting of poly(vinyl chloride), silicone rubber and polyurethane.

5. The reference electrode as set forth in claim 1 further comprising a correction electrode for more accurate self-diagnostic function.

6. The reference electrode as set forth in claim 5, wherein the correction electrode comprises a substrate;

a metal layer;

an insoluble metal salt layer; and

an insulating film for insulating the metal layer from a sample solution.

7. The reference electrode as set forth in claim 6, wherein the substrate of the correction electrode is prepared from plastic or ceramic, the metal layer of the correction electrode is prepared from a pure metal or an alloy, the insoluble metal salt layer of the correction electrode is prepared from a silver halide, and the insulating film of the correction electrode is prepared from an inorganic or an organic polymer.

8. The reference electrode as set forth in claim 7, wherein the substrate of the correction electrode is made of poly(vinyl chloride) or alumina (Al₂O₃);

the metal layer of the correction electrode is made of a metal selected from the group consisting of silver (Ag), platinum (Pt), gold (Au), copper (Cu) and alloys thereof;

the insoluble metal salt layer of the correction electrode is made of a silver halide selected from the group consisting of silver chloride (AgCl), silver bromide (AgBr) and silver iodide (AgI); and

the insulating film of the correction electrode is a ceramic film, a dielectric film or a photosensitive film.

9. The reference electrode as set forth in claim 5, wherein the correction electrode comprises a metal layer and an insoluble metal salt layer.

10. The reference electrode as set forth in claim 1, wherein the substrate is planar.

11. The reference electrode as set forth in claim 1, further comprising a working electrode formed on the substrate.

12. The reference electrode as set forth in claim 11, wherein the working electrode comprises a metal layer, an insoluble metal salt layer, an ion-selective membrane, the insulating film surrounding the ion-selective membrane.

13. The reference electrode as set forth in claim 11, further comprising a correction electrode formed on the substrate.

14. The reference electrode as set forth in claim 13, wherein the correction electrode comprises a metal layer and an insoluble metal salt layer.

15. The reference electrode as set forth in claim 1, wherein the ion-sensitive, protective membrane is selected from the group consisting of a potassium ion-, a sodium ion-, a calcium ion- and a chloride ion-selective electrode membrane.

16. The reference electrode as set forth in claim 1, wherein the ion-sensitive, protective membrane has a polymer support selected from the group consisting of poly(vinyl chloride), silicone rubber and polyurethane.

17. The reference electrode as set forth in claim 1, wherein the plurality of junctions consist of two junctions formed on opposite sides of the ion-sensitive, protective membrane.