REFERENCE HALF-CELL AND ELECTROCHEMICAL SENSOR WITH THE REFERENCE HALF-CELL

• US 20130161191A1
• Filed: 12/19/2012
• Published: 06/27/2013
• Est. Priority Date: 12/22/2011
• Status: Active Grant

• Current Assignee: Endress+Hauser Conducta Gesellschaft FUER Mess- und Regeltechnik mbH+Company KG
• Original Assignee: Endress + Hauser Conducta Gesellschaft Fur Mess- Und Regeltechnik Mbh + Co. Kg
• Inventors: Wilhelm, Thomas, Hanko, Michael, Trapp, Thilo, Schroter, Thomas, Nowak, Wolfram
• Granted Patent: US 9,696,273 B2
• Time in Patent Office: Days
• US Class Current: 204/406
• CPC Class Codes: G01N 27/301 Reference electrodes
• CPC Class Codes: G01N 27/31 Half-cells with permeable membranes, e.g. semi-porous or perm-selective membranes
• CPC Class Codes: G01N 27/333 Ion-selective electrodes or membranes glass electrodes G01N27/36
• CPC Class Codes: G01N 27/36 Glass electrodes
• CPC Class Codes: G01N 27/401 Salt-bridge leaks; Liquid junctions
• CPC Class Codes: G01N 27/414 Ion-sensitive or chemical field-effect transistors, i.e. ISFETS or CHEMFETS
• CPC Class Codes: G01N 27/416 Systems G01N27/27 takes precedence

Abstract

A reference half-cell for application in an electrochemical sensor, comprising a housing, in which a chamber containing a reference electrolyte is formed, wherein the reference electrolyte (5, 105) is in contact with a medium surrounding the housing via a liquid junction arranged in a wall of the housing, wherein the liquid junction comprises a porous diaphragm, especially a porous ceramic diaphragm, and wherein the diaphragm has, at least partially, a coating, which comprises at least one metal.

Claims

1-15. -15. (canceled)

16. A reference half-cell for application in an electrochemical sensor, comprising:

a housing, in which a chamber containing a reference electrolyte is formed, wherein the reference electrolyte is in contact with a medium surrounding said housing via a liquid junction arranged in a wall of said housing; and

a porous diaphragm comprising the liquid junction, especially a porous ceramic diaphragm, wherein;

said diaphragm has, at least partially, a coating, which comprises at least one metal.

17. The reference half-cell as claimed in claim 16, further comprising:

an electrode of a second type contained in said chamber and acting as a potential forming system, especially a silver/silver halide electrode.

18. The reference half-cell as claimed in claim 16, wherein:

said at least one metal is selected from the group consisting of;

copper, ruthenium, rhodium, palladium, silver, osmium, iridium, platinum and gold.

19. The reference half-cell as claimed in claim 16, wherein:

said coating has a biocidal effect.

20. The reference half-cell as claimed in claim 16, wherein:

said coating has a first layer formed of at least a first metal and at least one other, second layer lying over said first layer, especially applied directly on said first layer, and composed of said first metal and/or a second metal different from said first metal.

21. An electrochemical sensor for measuring at least one measured variable of a measured medium, comprising at least one reference half-cell having:

a housing, in which a chamber containing a reference electrolyte is formed, wherein the reference electrolyte is in contact with a medium surrounding said housing via a liquid junction arranged in a wall of said housing; and

a porous diaphragm comprising the liquid junction, especially a porous ceramic diaphragm, wherein;

said diaphragm has, at least partially, a coating, which comprises at least one metal.

22. The electrochemical sensor as claimed in claim 21, further comprising:

at least one sensorially active component in contact with the measured medium during measuring, and having a property changing as a function of the measured variable to be determined; and

a measuring circuit interacting with the reference half-cell and said sensorially active component and embodied to produce a measurement signal dependent on the property of said sensorially active component and representing the measured variable.

23. The electrochemical sensor as claimed in claim 22, wherein:

said sensorially active component comprises a metal redox electrode, a non-metallic redox electrode, the surface of a metal-metal oxide electrode, an EIS structure, especially an ion-selective, field effect transistor, or an ion-selective membrane, especially a glass membrane.

24. The electrochemical sensor as claimed in claim 21, further comprising:

a working electrode and a counter electrode, which, with the reference half-cell, form a three electrode arrangement; and

a control circuit, especially a potentiostatic or galvanostatic, control circuit, which is embodied to set a predetermined desired voltage between said counter electrode and said reference electrode, and to register, in such case, the electrical current flowing through the measured medium between said counter electrode and said working electrode, especially for performing voltametric or amperometric measurements.

25. A method for manufacturing a reference half-cell, comprising:

a housing, in which a chamber containing a reference electrolyte is formed, wherein the reference electrolyte is in contact with a medium surrounding said housing via a liquid junction arranged in a wall of said housing; and

a porous diaphragm comprising the liquid junction, especially a porous ceramic diaphragm, wherein;

said diaphragm has, at least partially, a coating, which comprises at least one metal, the method comprising the steps of;

providing a porous diaphragm, especially a porous ceramic diaphragm, in a housing wall of a housing;

forming a chamber for accommodating a reference electrolyte in the housing of the reference half-cell; and

coating the diaphragm, especially before or after connecting of the diaphragm with the housing wall, with a coating comprising at least one metal.

26. The method as claimed in claim 25, wherein:

the coating of the diaphragm with the coating comprising at least one metal comprises the steps of;

providing a porous stock, especially a porous ceramic stock;

contacting the stock with a solution containing the at least one metal in the form of a metal salt or in the form of nano particles, especially colloidal particles;

depositing from the solution a metal-comprising coating of the porous stock; and

isolating a segment of the coated porous stock for forming the diaphragm.

27. The method as claimed in claim 25, wherein:

the coating of the diaphragm with the coating comprising at least one metal comprises the steps of;

contacting the diaphragm connected with the housing wall by material bonding with a solution containing the at least one metal in the form of a metal salt or in the form of nano particles, especially colloidal particles; and

depositing a metal-comprising coating of the diaphragm from the solution.

28. The method as claimed in claim 26, wherein:

the depositing of a metal-comprising coating from the solution containing the metal in the form of a metal salt is performed currentlessly or galvanically.

29. The method as claimed in claim 26, wherein:

the depositing of a metal-comprising coating from the solution containing the metal in the form of a metal salt or in the form of nano particles, especially colloidal particles is performed by thermal treatment, especially by firing, the stock, or diaphragm, supplied with the solution.

30. The method as claimed in claim 26, wherein:

before depositing the coating comprising at least one metal, a layer promoting adhesion of the metal-comprising coating is applied on the stock, or the diaphragm.