Thin film mixed potential sensors
View Patent ↗A mixed potential sensor for oxidizable or reducible gases and a method of making. A substrate is provided and two electrodes are formed on a first surface of the substrate, each electrode being formed of a different catalytic material selected to produce a differential voltage between the electrodes from electrochemical reactions of the gases catalyzed by the electrode materials. An electrolytic layer of an electrolyte is formed over the electrodes to cover a first portion of the electrodes from direct exposure to the gases with a second portion of the electrodes uncovered for direct exposure to the gases.
1. A mixed potential sensor for oxidizable or reducible gases comprising:
a substrate;
two electrodes formed on a first surface of the substrate, each electrode being formed of a different catalytic material selected to produce a differential voltage between the electrodes from electrochemical reactions of the gases catalyzed by the electrode materials; and
an electrolytic layer of an oxygen ion conducting metal oxide electrolyte formed over the electrodes to cover a first portion of the electrodes from direct exposure to the gases, with a second portion of the electrodes uncovered for direct exposure to the gases.
2. The mixed potential sensor of claim 1 , wherein the substrate is an inert, gas impermeable material.
3. The mixed potential sensor of claim 2 , wherein the electrodes have a density characteristic of materials deposited by RF magnetron or DC sputter vapor deposition processes.
4. The mixed potential sensor of claim 1 , wherein the electrodes have a density characteristic of materials deposited by RF magnetron or DC sputter vapor deposition processes.
5. The mixed potential sensor of any one of claims 1 - 3 , wherein the electrolytic layer is formed to a thickness of 5 μm to 10 μm with a density characteristic of materials deposited by an electron beam evaporation process.
6. The mixed potential sensor of claim 1 wherein said oxygen ion conducting metal oxide electrolyte is selected from yttria stabilized-zirconia, zirconia-based electrolytes, ceria-based electrolytes, or bismuth-based electrolytes.
7. The mixed potential sensor of claim 6 wherein said oxygen ion conducting metal oxide electrolyte is yttria stabilized-zirconia.
8. A method for making a mixed potential sensor for oxidizable or reducible gases comprising:
providing a gas impermeable substrate;
forming electrode strips of two different materials effective to produce a differential potential therebetween in electrochemical reactions with one of the oxidizable or reducible gases;
depositing a thin, dense layer of an oxygen ion conducting metal oxide electrolyte to cover a first portion of the electrodes from direct exposure to the gases while leaving a second portion of the electrodes uncovered for direct exposure to the gases.
9. The method of claim 8 , including forming the electrodes by a deposition process selected from the group consisting of RF magnetron vapor deposition or DC sputter vapor deposition.
10. The method of claim 8 , including depositing said layer of said oxygen ion conducting metal oxide electrolyte by an electron beam evaporation process.
11. The method of claim 8 wherein said oxygen ion conducting metal oxide electrolyte is selected from yttria stabilized-zirconia, zirconia-based electrolytes, ceria-based electrolytes, or bismuth-based electrolytes.
12. The method of claim 11 wherein said oxygen ion conducting metal oxide electrolyte is yttria stabilized-zirconia.