Electrochemical sensor compensated for relative humidity
The invention relates to an electrochemical gas sensor having both a reference sensor and an active sensor, whereby each reference and active sensor includes a substrate, a counter electrode deposited on a surface of the substrate, a sensing electrode also deposited on the surface, and a solid electrolytic material in electrical contact with both electrodes for carrying a flow of ions between them, which measures a concentration of a gas and compensates for relative humidity differences between sample gas and surrounding atmosphere. The sensor also includes a layer of solid electrolytic material on the sensing electrode of the reference sensor and a film of solid electrolytic material on the sensing electrode of the active sensor, whereby the layer is thicker than the film. The invention may further include a reference electrode in both the reference and active sensors for improving sensor accuracy and/or repeatability.
1. An electrochemical gas sensor comprising:
a substrate having a surface;
a reference sensor having a first counter electrode, first sensing electrode, and first reference electrode deposited on said surface;
an active sensor having a second counter electrode, second sensing electrode, and second reference electrode deposited on said surface, said reference sensor and said active sensor being spaced apart from one another;
a first electrolytic material having a first thickness and being in contact with said first sensing electrode for carrying a flow of ions;
a second electrolytic material having a second thickness and being in contact with said second sensing electrode for carrying a flow of ions, said second thickness being less than said first thickness; and
additional electrolytic material in contact with active sensor and reference sensor, wherein said additional electrolytic material acts as a conductive medium to carry ions from the active sensor to the reference sensor.
2. The electrochemical gas sensor of claim 1 , wherein said first and said second sensing electrodes are the same material.
3. The electrochemical gas sensor of claim 1 , wherein said first and said second sensing electrodes are different materials.
4. The electrochemical gas sensor of claim 1 , wherein said first sensing electrode includes a material inert to a gas.
5. The electrochemical gas sensor of claim 1 , wherein said first sensing electrode includes gold.
6. The electrochemical gas sensor of claim 1 , further comprising a reservoir in contact with said first electrolytic material on a side opposite of said substrate.
7. The electrochemical gas sensor of claim 6 , further comprising a solution in said reservoir for hydrating said electrolytic material.
8. The electrochemical gas sensor of claim 1 , wherein the first electrolytic material is between 10 and 60 micrometers thick.
9. The electrochemical gas sensor of claim 1 , further comprising a solution for wetting the first electrolytic material and the second electrolytic material.
10. The electrochemical gas sensor of claim 1 , wherein the second electrolytic material is between 2.5 and 30 micrometers thick.
11. The electrochemical gas sensor of claim 1 , wherein the thickness of said additional electrolytic material is greater than the thickness of both the first electrolytic material and second electrolytic material.
12. The electrolytic gas sensor of claim 1 , wherein the thickness of the additional electrolytic material is approximately between 0.0002 and 0.04 inches thick.
13. An electrochemical gas sensor comprising:
a first cell in communication with a second cell;
each cell having:
a substrate having a surface;
an electrode being deposited on said surface, said electrode being both a counter and reference electrode;
a first sensing electrode and a second sensing electrode, being spaced apart from one another and from said counter and reference electrode, being deposited on said surface;
a first electrolytic material in contact with said first sensing electrode for carrying a flow of ions;
a second electrolytic material in contact with said second sensing electrode for carrying a flow of ions; and
additional electrolytic material in contact with the first sensing electrode and the second sensing electrode, wherein the additional electrolytic material acts as a conductive medium to carry ions from the second sensing electrode to the first sensing electrode.
14. The electrochemical gas sensor of claim 13 , wherein said first electrolytic material includes a first thickness.
15. The electrochemical gas sensor of claim 13 , wherein said first electrolytic material includes a first thickness and said second electrolytic material includes a second thickness, said second thickness being less than said first thickness.
16. The electrochemical gas sensor of claim 13 , wherein said first and said second sensing electrodes are the same material.
17. The electrochemical gas sensor of claim 13 , wherein said first and said second sensing electrodes are different materials.
18. The electrochemical gas sensor of claim 13 , further comprising a reservoir in contact with said first electrolytic material on a side opposite of said substrate.
19. An electrochemical gas sensor comprising:
a substrate having a surface;
three electrodes, said electrodes comprising a counter/reference electrode, a first sensing electrode and a second sensing electrode, said counter/reference electrode, said first sensing electrode and said second sensing electrode being spaced apart from one another and deposited on said surface of said substrate;
a first electrolytic material having a first thickness and being in contact with said first sensing electrode for carrying a flow of ions;
a second electrolytic material having a second thickness and being in contact with said second sensing electrode for carrying a flow of ions, said second thickness being less than said first thickness; and
additional electrolytic material in contact with the three electrodes, wherein the additional electrolytic material acts as a conductive medium to carry ions from the second sensing electrode to the first sensing electrode.
20. The electrochemical gas sensor of claim 19 , further comprising a reservoir in contact with said first electrolytic material on a side opposite of said substrate.
21. The electrochemical gas sensor of claim 19 , further comprising a solution in said reservoir for hydrating said electrolytic material.