# US 5,573,798 A · Method of manufacturing an electrode for measuring pH

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- Number: US 5,573,798 A
- Document ID: US5573798A
- Status: Granted
- Kind: A
- Application number: 08/463,438
- Filed: 1995-06-05
- Granted: 1996-11-12
- Earliest claimed: 1990-08-22
- Assignees: Toa Electronics Ltd.
- Inventors: Akihiko Kato; Masaharu Yamasato; Tomio Taguchi; Yoshiki Yanagida; Teruaki Katube
- Web page: https://patentgrep.com/patent/US5573798A

## CPC

- G01N 27/333: Ion-selective electrodes or membranes (glass electrodes G01N27/36)
- G01N: INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES (measuring or testing apparatus or processes other than immunoassay, involving enzymes or microorganisms C12M, C12Q)

## Abstract

This invention relates to a pH measuring electrode having a sensor film which is sensitive to a hydrogen ion (H.sup.+) in the solution. The pH measuring electrode of this invention has a sensor film of a metal oxide deposited on an electrically insulative ceramics substrate so that the sensor film can be very miniaturized in its size. Therefore, the entire pH measuring electrode can be made considerably small and simple in construction. Also, this invention provides another pH measuring electrode which further includes a porous film of an insulation material coated on the surface of the metal oxide sensor film so that the sensor film is not affected by any coexistent substances.

## Claims

### Claim 1

A method of producing pH measuring electrodes, comprising the steps of:
covering the surface of an electrically conductive support body with a thin insulation film;
removing a portion of said insulation film; and forming a pH sensitive film at least on the portion of the conductive support body where the insulation film was removed, said pH sensitive film comprising iridium oxide, the ratio of iridium to oxygen in said iridium oxide being from 1:2.5 to 1:3.5.

### Claim 2 (depends on 1)

The method of producing pH measuring electrodes according to claim 1, wherein said step of removing a portion of the insulation film is achieved by forming the pH sensitive film using sputtering.

### Claim 3 (depends on 1)

The method of producing pH measuring electrodes according to claim 1, further comprising the step of coating with a porous film of an insulation material at least a portion of the iridium oxide where the iridium oxide is to contact with a solution whose pH is to be measured.

### Claim 4 (depends on 1)

The method of producing pH measuring electrodes according to claim 1, wherein said step of removing a portion of the insulation film is achieved by forming the pH sensitive film using ion beam deposition.

### Claim 5

A method of producing pH measuring electrodes, comprising the steps of:
forming a pH sensitive film on a portion of an electrically conductive support body, said pH sensitive film comprising iridium oxide, the ratio of iridium to oxygen in said iridium oxide being from 1:2.5 to 1:3.5; and
thereafter covering the remaining portion of said support body with an insulation film.

### Claim 6 (depends on 5)

The method of producing pH measuring electrodes according to claim 5, further comprising the step of coating with a porous film of an insulation material at least a portion of the iridium oxide where the iridium oxide is to contact with a solution whose pH is to be measured.

### Claim 7

A method of producing pH measuring electrodes, comprising the step of:
forming a pH sensitive film on a surface of an electrically insulative ceramics substrate, said pH sensitive film comprising iridium oxide, the ratio of iridium to oxygen in said iridium oxide being from 1:2.5 to 1:3.5.

### Claim 8 (depends on 7)

The method of producing pH measuring electrodes according to claim 7, further comprising the step of polishing the substrate to a mirror finish prior to forming the pH sensitive film thereon, wherein said step of forming the pH sensitive film is achieved by sputtering.

### Claim 9 (depends on 7)

The method of producing pH measuring electrodes according to claim 7, further comprising the step of coating with a porous film of an insulation material at least a portion of the iridium oxide where the iridium oxide is to contact with a solution whose pH is to be measured.