Electrode for measuring pH
First Claim
1. a pH measuring electrode comprising:
- an electrically conductive metal substrate;
an electrically insulative film covering a part of a surface of said metal substrate;
a pH sensitive film comprising iridium oxide contacting said metal substrate so as to be electrically connected thereto, the ratio of iridium to oxygen in said iridium oxide being from 1;
2.5 to 1;
3.5;
a porous insulation film deposited on at least the portion of the outer surface of the iridium oxide film where the iridium oxide film is to contact a solution whose pH is to be measured, said porous film having pores with a diameter of 3 Å
to 15 Å
so that only hydrogen ions, and no other ions, are permitted to pass through said porous film; and
a lead-out conductor connected to said metal substrate.
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Accused Products
Abstract
This invention relates to a pH measuring electrode having a sensor film which is sensitive to a hydrogen ion (H+) in the solution and method of manufacturing the same. The pH measuring electrode of this invention has a sensor film of a metal oxide deposited on an electrically conductive support 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.
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Citations
10 Claims
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1. a pH measuring electrode comprising:
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an electrically conductive metal substrate; an electrically insulative film covering a part of a surface of said metal substrate; a pH sensitive film comprising iridium oxide contacting said metal substrate so as to be electrically connected thereto, the ratio of iridium to oxygen in said iridium oxide being from 1;
2.5 to 1;
3.5;a porous insulation film deposited on at least the portion of the outer surface of the iridium oxide film where the iridium oxide film is to contact a solution whose pH is to be measured, said porous film having pores with a diameter of 3 Å
to 15 Å
so that only hydrogen ions, and no other ions, are permitted to pass through said porous film; anda lead-out conductor connected to said metal substrate. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A pH electrode comprising:
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an electrically conductive metal substrate comprising tantalum and having an electrically insulative film comprising tantalum pentoxide on a portion of a surface of said substrate; a pH sensitive film comprising iridium oxide directly on said metal substrate so as to be electrically connected thereto, the ratio of iridium to oxygen of said iridium oxide being from 1;
2.5 to 1;
3.5;a porous insulation film of tantalum pentoxide directly deposited on the outer surface of said iridium oxide film by sputtering, said porous insulation film having pores, the diameter of each of which is between 3 Å and
15 Å
so that only hydrogen ions are permitted to pass through the pores and other ions are not permitted to pass therethrough; anda lead-out conductor connected to said metal substrate. - View Dependent Claims (10)
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Specification