Drift compensation for gas component sensors

• US 20020092779A1
• Filed: 07/26/2001
• Published: 07/18/2002
• Est. Priority Date: 02/04/2000
• Status: Abandoned Application

• Current Assignee: AirIQ LLC (AirIQ Inc.)
• Original Assignee: AirIQ LLC (AirIQ Inc.)
• Inventors: Essalik, Abdeltif, Rosen, Howard
• Application Number:
  US09/917,150
• Publication Number:
  US 20020092779A1
• Time in Patent Office: Days
• US Class Current: 205/781
• CPC Class Codes: G01N 27/4073 Composition or fabrication of the solid electrolyte

Abstract

The present invention is a gas component sensor comprising novel electrolyte compositions. The electrolyte compositions in bulk, sintered or thin film embodiments are capable of forming with different-metal sensing and reference electrodes a highly stable gas oxide sensors. The novel electrolyte composition changes electrochemical reactions at the sensing and reference electrodes and the overall reaction of the electrodes and electrolyte. The novel electrolyte compositions have: (1) excellent chemical stability and thermal compatibility as to the electrodes and a preferred ceramic substrate, (2) excellent chemical stability with the environment as to the reference and sensing electrodes, which need not be sealed against the atmosphere to be sensed, (3) effective adherence to the substrate and electrode metals. An improvement is disclosed where a correction of calculated gas concentration is made by comparison of measured voltages of two gas sensors.

Claims

1. A drift correction method comprising gas sensor assemblies selected from the types of a carbon dioxide gas sensor assembly, an oxides of nitrogen gas sensor assembly, and an oxides of sulfur gas sensor assembly, comprising:

(a) each carbon dioxide gas sensor assembly comprises;

(i) a first electrolyte comprising one or more alkali metal carbonates, one or more alkaline earth metal carbonates, and one or more first reference electrode metal halogens, wherein the reference electrode metal of the first reference electrode metal halogens is chosen from the group consisting of ruthenium, rhodium, palladium, rhenium, osmium, iridium, platinum and gold and the halogens of the first reference metal halogens are chlorine, bromine or iodine;

(ii) the first electrolyte in electrochemical connection between a first sensing electrode and a first reference electrode, such that the first reference electrode consists of a first reference electrode metal and the sensing electrode consists of any other reference electrode metal; and

(iii) the first electrolyte and first electrodes are supported on a first substrate;

(b) each oxides of nitrogen gas sensor assembly comprises;

(i) a second electrolyte comprising one or more alkali metal nitrates, one or more alkaline earth metal nitrates, and one or more second reference electrode metal halogens, wherein the reference electrode metal of the second reference electrode metal halogens is chosen from the group consisting of ruthenium, rhodium, palladium, rhenium, osmium, iridium, platinum and gold and the halogens of the second reference metal halogens are chlorine, bromine or iodine;

(ii) the second electrolyte in electrochemical connection between a second sensing electrode and a second reference electrode, such that the second reference electrode consists of a second reference electrode metal and the sensing electrode consists of any other reference electrode metal; and

(iii) the second electrolyte and second electrodes are supported on a second substrate;

(c) each oxides of sulfur gas sensor assembly comprises;

(i) a third electrolyte comprising one or more alkali metal sulfate, one or more alkaline earth metal sulfates, and one or more third reference electrode metal halogens, wherein the reference electrode metal of the third reference electrode metal halogens is chosen from the group consisting of ruthenium, rhodium, palladium, rhenium, osmium, iridium, platinum and gold and the halogens of the third reference metal halogens are chlorine, bromine or iodine;

(ii) the third electrolyte in electrochemical connection between a third sensing electrode and a third reference electrode, such that the third reference electrode consists of a third reference electrode metal and the sensing electrode consists of any other reference electrode metal; and

(iii) the third electrolyte and third electrodes are supported on a third substrate;

(d) a first gas sensor assembly of a first type exposed to a gas to be sensed;

(e) a second gas sensor assembly of the first type sealed against the gas to be sensed; and

(f) having the first and second gas sensor assemblies electrically connected to means for separately measuring a voltage across them and for comparing those measured voltages, exposing the first gas sensor assembly to a gas to be sensed, operating the first and second gas sensor assemblies, and measuring and comparing the voltages of the first and second gas sensor assemblies.

2. The method of claim 1 wherein the first and second gas sensors assemblies are carbon dioxide gas sensor assemblies and the gas to be sensed comprises carbon dioxide.

3. The method of claim 1 wherein the first and second gas sensors assemblies are oxides of nitrogen gas sensor assemblies and the gas to be sensed comprises oxides of nitrogen.

4. The method of claim 1 wherein the first and second gas sensors assemblies are oxides of sulfur gas sensor assemblies and the gas to be sensed comprises oxides of sulfur.

5. The method of claim 1 wherein a difference in the voltages across the first and second gas sensors assemblies is used to calculate a correction to a calculated concentration of a component in the gas to be sensed based on the voltage across the first gas sensor assembly.

6. The method of claim 1 wherein a difference in the voltages across the first and second gas sensors assemblies is used to calculate a correction to a calculated concentration of a component in the gas to be sensed based on the voltage across the first gas sensor assembly.

7. The sensor of claim 6 wherein a the corrected and calculated concentration of a component of the gas to be sensed is displayed, stored or used in the operation of a control system.

8. An array of two or more gas sensor assemblies selected from the types of a carbon dioxide gas sensor assembly, an oxides of nitrogen gas sensor assembly, or an oxides of sulfur gas sensor assembly, comprising:

(a) each carbon dioxide gas sensor assembly comprises;

(i) a first electrolyte comprising one or more alkali metal carbonates, one or more alkaline earth metal carbonates, and one or more first reference electrode metal halogens, wherein the reference electrode metal of the first reference electrode metal halogens is chosen from the group consisting of ruthenium, rhodium, palladium, rhenium, osmium, iridium, platinum and gold and the halogens of the first reference metal halogens are chlorine, bromine or iodine;

(ii) the first electrolyte in electrochemical connection between a first sensing electrode and a first reference electrode, such that the first reference electrode consists of a first reference electrode metal and the sensing electrode consists of any other reference electrode metal; and

(iii) the first electrolyte and first electrodes are supported on a first substrate;

(b) each oxides of nitrogen gas sensor assembly comprises;

(i) a second electrolyte comprising one or more alkali metal nitrates, one or more alkaline earth metal nitrates, and one or more second reference electrode metal halogens, wherein the reference electrode metal of the second reference electrode metal halogens is chosen from the group consisting of ruthenium, rhodium, palladium, rhenium, osmium, iridium, platinum and gold and the halogens of the second reference metal halogens are chlorine, bromine or iodine;

(ii) the second electrolyte in electrochemical connection between a second sensing electrode and a second reference electrode, such that the second reference electrode consists of a second reference electrode metal and the sensing electrode consists of any other reference electrode metal; and

(iii) the second electrolyte and second electrodes are supported on a second substrate;

(c) each oxides of sulfur gas sensor assembly comprises;

(i) a third electrolyte comprising one or more alkali metal sulfate, one or more alkaline earth metal sulfates, and one or more third reference electrode metal halogens, wherein the reference electrode metal of the third reference electrode metal halogens is chosen from the group consisting of ruthenium, rhodium, palladium, rhenium, osmium, iridium, platinum and gold and the halogens of the third reference metal halogens are chlorine, bromine or iodine;

(ii) the third electrolyte in electrochemical connection between a third sensing electrode and a third reference electrode, such that the third reference electrode consists of a third reference electrode metal and the sensing electrode consists of any other reference electrode metal; and

(iii) the third electrolyte and third electrodes are supported on a third substrate;

(d) a first gas sensor assembly of a one type is adapted to be exposed to a first gas to be sensed; and

(e) a second gas sensor assembly of one other type is adapted to be exposed to the first gas to be sensed.

9. The array of claim 8 wherein a third gas sensor assembly of a last type is adapted to be exposed to the first gas to be sensed.

10. The array of claim 8 wherein a selectively permeable membrane seals at least one of the gas sensor assemblies against the first gas to be sensed such that at least one component of the first gas to be sensed is substantially excluded from the first gas to be sensed reaching the electrolyte of the gas sensor assembly.

11. The array of claim 8 wherein the first gas sensor assembly is a carbon dioxide gas sensor assembly and the second gas sensor assembly is an oxides of nitrogen gas sensor assembly.

12. The array of claim 8 wherein the first gas sensor assembly is a carbon dioxide gas sensor assembly and the second gas sensor assembly is an oxides of sulfur gas sensor assembly.

13. The array of claim 8 wherein the first gas sensor assembly is a oxides of nitrogen gas sensor assembly and the second gas sensor assembly is an oxides of sulfur gas sensor assembly.