Sensor for measuring electrical conductivity

• US 4,719,441 A
• Filed: 02/14/1986
• Issued: 01/12/1988
• Est. Priority Date: 02/26/1985
• Status: Expired due to Fees

• Current Assignee: Defensor AG, Novasina AG
• Original Assignee: Navasina AG
• Inventors: Horn, Petr
• Primary Examiner(s): Shaw, Clifford C.
• Assistant Examiner(s): LATEEF, MARVIN M
• Application Number:
  US06/830,516
• Time in Patent Office: 697 Days
• Field of Search: 338/22 R, 338/22 SD, 338/25, 338/20, 338/306-308, 29/611, 29/612, 73/362 AR, 427/127, 427/125, 427/96
• US Class Current: 338/20
• CPC Class Codes: G01N 27/07 Construction of measuring vessels; Electrodes therefor
• CPC Class Codes: Y10T 29/49083 Heater type

Abstract

At least two electrodes (1, 2) each provided with at least one lead (5) are applied in the form of conductor tracks to a substrate. The leads (5) can be made of a material having a lower standard potential than that of the electrodes (1, 2). A dielectric (6) covers the electrode ends and, up to the contact points (4), the leads (5). As required, the electrodes (1, 2) can be designed and used as a heating electrode and/or as a temperature sensor. Moreover, the electrodes can be arranged on one side or on both sides of the substrate board (7).

Claims

1. A sensor for measuring electrical conductivity, comprising:

an electrically-insulating substrate, the substrate being one of heat and corrosion resistant

at least two, spaced electrodes exposed on the substrate, the electrodes being one of heat and corrosion resistant;

at least two electrically-conductive leads on the substrate, one end of each lead overlapping a portion of a respective one of the electrode; and

a dielectric covering the leads, the dielectric being one of heat and corrosion resistant whereby to define a measuring area of the exposed electrodes on one side of the one, dielectric-covered, lead-overlapped ends of the electrodes, except for a contact-point portion of each lead at the other end thereof, remote from the one end overlapping the electrode, whereby to define a contact point thereat.

2. A sensor as claimed in claim 1, wherein the electrodes and the leads are made of different materials, the electrode material having a higher standard potential than the material of the leads.

3. A sensor as claimed in claim 1, wherein the electrodes consist of platinum.

4. A sensor as claimed in claim 1, wherein the substrate is made of alumina to the extent of more than 95%.

5. A sensor as claimed in claim 3, wherein the leads consist of silver/palladium.

6. A sensor as claimed in claim 5, wherein the leads have tin-plated contact points.

7. A sensor as claimed in claim 1, wherein one electrode is arranged on the other side of the substrate relative to the remaining electrodes.

8. A sensor as claimed in claim 1, wherein one of the two electrodes has at least two leads for use as one of a heating electrode and a temperature sensor.

9. A sensor as claimed in claim 1, wherein one electrode has two leads for use as a heating element, and another electrode has at least two leads for use as a temperature sensor.

10. A process for the production of the sensor as claimed in claim 2, which comprises, a first operation of applying electrodes to a substrate, a second operation of applying leads to the substrate and firing them at a temperature below the melting point of the electrodes, and finally, a third operation of applying a dielectric to the substrate and firing it at a temperature below the melting point of the leads.

11. A method of measuring electrical conductivity, comprising:

providing an electrically-insulating substrate, the substrate being one of heat and corrosion resistant;

providing at least two, spaced electrodes exposed on the substrate, the electrodes being one of heat and corrosion resistant;

providing at least three electrically-conductive leads on the substrate, one end of one lead overlapping a portion of one of the electrodes and one end of the other two leads overlapping spaced portions of the other electrode;

providing a dielectric covering the leads, the dielectric being one of heat and corrosion resistant, whereby to define a measuring area of the exposed electrodes on one side of the one, dielectri-covered, lead-overlapped ends of the electrodes, except for a contact-point portion of each lead at the other end thereof, remote from the one end overlapping the electrode, whereby to define a contact point thereat;

applying an electric potential across the contact point portions of the other two leads to heat the electrode overlapped thereby conductively sufficiently to clean off a deposit on the substrate between the electrodes; and

sensing the electrical conductivity of the deposit at the contact point portion of the one electrode while so applying the electric potential.