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Electrode for measuring pH

  • US 5,320,735 A
  • Filed: 08/19/1991
  • Issued: 06/14/1994
  • Est. Priority Date: 08/22/1990
  • Status: Expired due to Fees
First Claim
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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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