Method and apparatus for analyzing mixtures of gases

• US 6,960,476 B2
• Filed: 10/15/2001
• Issued: 11/01/2005
• Est. Priority Date: 10/16/2000
• Status: Expired due to Fees

• Current Assignee: E. I. du Pont de Nemours and Company (Corteva, Inc.)
• Original Assignee: E. I. du Pont de Nemours and Company (Corteva, Inc.)
• Inventors: Morris, Patricia A.
• Primary Examiner(s): Warden, Jill
• Assistant Examiner(s): Sines, Brian J.
• Application Number:
  US09/977,791
• Publication Number:
  US 20020121440A1
• Time in Patent Office: 1,478 Days
• Field of Search: 422/50, 422/83, 422/88, 422/94, 422/95, 422/96, 422/97, 422/98, 436/43, 436/149, 436/151, 73/10.1, 73/10.2, 73/232, 73/233.1, 73/310.6
• US Class Current: 436/149
• CPC Class Codes: G01N 33/0031 comprising two or more sensors, e.g. a sensor array
• CPC Class Codes: Y10T 436/11 Automated chemical analysis

Abstract

Disclosed herein is a method and apparatus for analyzing, sensing and measuring the concentrations of various gases, including NO_x, hydrocarbons, carbon monoxide and oxygen, in a multi-component gas system using chemical sensors and chemical sensor arrays. The sensors and sensor arrays use chemo/electro-active materials to analyze and detect the presence of gases.

Claims

1. A method for calculating the concentration of at least two individual analyte gas components in a multi-component gas mixture having a temperature of about 400°

C. or more, comprising;

(a) providing within the gas mixture an array of at least three chemo/electro-active materials, each chemo/electro-active material having a different electrical response characteristic upon exposure to each of the individual analyte gas components than each of the other chemo/electro-active materials, wherein at least one chemo/electro-active material, when at a temperature of about 400°

C. or more,

(i) has an electrical resistivity in the range of about 1 ohm-cm to about 10⁵ ohm-cm, and

(ii) exhibits a change in electrical resistance of at least about 0.1 percent upon exposure of the material to an analyte gas component, as compared to the resistance before exposure;

(b) heating the array to a temperature above 500°

C.;

(c) determining an electrical response of each chemo/electro-active material upon exposure of the array to the unseparated components of the gas mixture;

(d) inputting the electrical responses of the chemo/electro-active materials, but not a baseline response value, a comparison response value or a reference gas value, to a pattern recognition technique; and

(e) calculating the concentration of each of the individual analyte gas components from the inputs in step (d).

2. A method according to claim 1 wherein the gas mixture is an emission from a combustion process.

3. A method according to claim 1 wherein the electrical response characteristic of each material upon exposure to the gas mixture at a selected temperature is quantifiable as a value, and the response value of at least one material is constant or varies by no more than about twenty percent during exposure of the material to an analyte gas component at the selected temperature for a period of at least about one minute.

4. A method according to claim 1 wherein the electrical response is selected from the group consisting of resistance, impedance, capacitance, voltage or current.

5. A method according to claim 1 wherein the gas mixture comprises one or more members of the group consisting of oxygen, carbon monoxide, a nitrogen oxide, a hydrocarbon, CO₂, H₂S, sulfur dioxide, a halogen, hydrogen, water vapor, ammonia, alcohol, a solvent vapor, an ether, a ketone, an aldehyde, a carbonyl, and a microorganism.

6. A method according to claim 1 wherein the gas mixture comprises one or more members of the group consisting of oxygen, a nitrogen oxide, a hydrocarbon, and ammonia.

7. A method according to claim 1 wherein the gas mixture comprises one or more members of the group consisting of a nitrogen oxide and ammonia.

8. A method according to claim 1 wherein the gas mixture comprises one or more members of the group consisting of oxygen and a hydrocarbon.

9. A method according to claim 1 wherein the gas mixture is provided from a manufacturing process, a waste stream, environmental monitoring, or a medical, agricultural, food or beverage operation.

10. A method according to claim 1 wherein at least one chemo/electro-active material is a metal oxide.

11. A method according to claim 10 wherein the chemo/electro-active materials comprise one or more members of the group consisting of M¹O_x, M¹_aM²_bO_x, and M¹_aM²_bM³_cO_x wherein

M¹, M² and M³ are metals that form stable oxides when fired in the presence of oxygen above 500°

C.;

M¹ is selected from Periodic Groups 2-15 and the lanthanide group;

M² and M³ are independently selected from Periodic Groups 1-15 and the lanthanide group;

a, b, and c are each independently in the range of about 0.0005 to about 1, provided that a+b+c=1; and

x is a number sufficient so that the oxygen present balances the charges of the other elements in the compound.

12. A method according to claim 10 wherein the chemo/electro-active materials comprise one or more members of the group consisting of M¹O_x, M¹_aM²_bO_x, and M¹_aM²_bM³_cO_x wherein

M¹ is selected from the group consisting of Ce, Co, Cu, Fe, Ga, Nb, Ni, Pr, Ru, Sn, Ti, Tm, W, Yb, Zn, and Zr;

M² and M³ are each independently selected from the group consisting of Al, Ba, Bi, Ca, Cd, Ce, Co, Cr, Cu, Fe, Ga, Ge, In, K, La, Mg, Mn, Mo, Na, Nb, Ni, Pb, Pr, Rb, Ru, Sb, Sc, Si, Sn, Sr, Ta, Ti, Tm, V, W, Y, Yb, Zn, and Zr, but M² and M³ are not the same m M¹_aM²_bM³_cO_x;

a, b, and c are each independently in the range of about 0.0005 to about 1, provided that a+b+c=1; and

x is a number sufficient so that the oxygen present balances the charges of the other elements in the compound.

13. A method according to claim 10 wherein the chemo/electro-active materials comprise one or more members of the group consisting of M¹O_x, M¹_aM²_bO_x, and M¹_aM²_bM³_cO_x wherein

M¹O_x is selected from the group consisting of Ce_aO_x, CoO_x, CuO_x, FeO_x, GaO_x, NbO_x, NiO_x, PrO_x, RuO_x, SnO_x, Ta_aO_x, TiO_x, TmO_x, WO_x, YbO_x, ZnO_x, ZrO_x, SnO_x with Ag additive, ZnO_x with Ag additive, TiO_x with Pt additive, ZnO_x with frit additive, NiO_x with frit additive, SnO_x with frit additive, or WO_x with frit additive;

M¹_aM²_bO_x is selected from the group consisting of Al_aCr_bO_x, Al_aFe_bO_x, Al_aMg_bO_x, Al_aNi_bO_x, Al_aTi_bO_x, Al_aV_bO_x, Ba_aCu_bO_x, Ba_aSn_bO_x, Ba_aZn_bO_x, Bi_aRu_bO_x, Bi_aSn_bO_x, Bi_aZn_bO_x, Ca_aSn_bO_x, Ca_aZn_bO_x, Cd_aSn_bO_x, Cd_aZn_bO_x, Ce_aFe_bO_x, Ce_aNb_bO_x, Ce_aTi_bO_x, Ce_aV_bO_x, Co_aCu_bO_x, Co_aGe_bO_x, Co_aLa_bO_x, Co_aMg_bO_x, Co_aNb_bO_x, Co_aPb_bO_x, Co_aSn_bO_x, Co_aV_bO_x, Co_aW_bO_x, Co_aZn_bO_x, Cr_aCu_bO_x, Cr_aLa_bO_x, Cr_aMn_bO_x, Cr_aNi_bO_x, Cr_aSi_bO_x, Cr_aTi_bO_x, Cr_aY_bO_x, Cr_aZn_bO_x, Cu_aFe_bO_x, Cu_aGa_bO_x, Cu_aLa_bO_x, Cu_aNa_bO_x, Cu_aNi_bO_x, Cu_aPb_bO_x, Cu_aSn_bO_x, Cu_aSr_bO_x, Cu_aTi_bO_x, Cu_aZn_bO_x, Cu_aZr_bO_x, Fe_aGa_bO_x, Fe_aLa_bO_x, Fe_aMo_bO_x, Fe_aNb_bO_x, Fe_aNi_bO_x, Fe_aSn_bO_x, Fe_aTi_bO_x, Fe_aW_bO_x, Fe_aZn_bO_x, Fe_aZr_bO_x, Ga_aLa_bO_x, Ga_aSn_bO_x, Ge_aNb_bO_x, Ge_aTi_bO_x, In_aSn_bO_x, K_aNb_bO_x, Mn_aNb_bO_x, Mn_aSn_bO_x, Mn_aTi_bO_x, Mn_aY_bO_x, Mn_aZn_bO_x, Mo_aPb_bO_x, Mo_aRb_bO_x, Mo_aSn_bO_x, Mo_aTi_bO_x, Mo_aZn_bO_x, Nb_aNi_bO_x, Nb_aNi_bO_x, Nb_aSr_bO_x, Nb_aTi_bO_x, Nb_aW_bO_x, Nb_aZn_aO_x, Ni_aSi_bO_x, Ni_aSn_bO_x, Ni_aY_bO_x, Ni_aZn_bO_x, Ni_aZr_bO_x, Pb_aSn_bO_x, Pb_aZn_bO_x, Rb_aW_bO_x, Ru_aSn_bO_x, Ru_aW_bO_x, Ru_aZn_bO_x, Sb_aSn_bO_x, Sb_aZn_bO_x, Sc_aZr_bO_x, Si_aSn_bO_x, Si_aTi_bO_x, Si_aW_bO_x, Si_aZn_bO_x, Sn_aTa_bO_x, Sn_aTi_bO_x, Sn_aW_bO_x, Sn_aZn_bO_x, Sn_aZr_bO_x, Sr_aTi_bO_x, Ta_aTi_bO_x, Ta_aZn_bO_x, Ta_aZr_bO_x, Ti_aV_bO_x, Ti_aW_bO_x, Ti_aZn_bO_x, Ti_aZr_bO_x, V_aZn_bO_x, V_aZr_bO_x, W_aZn_bO_x, W_aZr_bO_x, Y_aZr_bO_x, Zn_aZr_bO_x, Al_aNi_bO_x with frit additive, Cr_aTi_bO_x with frit additive, Fe_aNi_bO_x with frit additive, Fe_aTi_bO_x with frit additive, Nb_aTi_bO_x with frit additive, Nb_aW_bO_x with frit additive, Ni_aZn_bO_x with fit additive, Ni_aZr_bO_x with frit additive, or Ta_aTi_bO_x with frit additive; and

M¹_aM²_bM³_cO_x is selected from the group consisting of Al_aMg_bZn_cO_x, Al_aSi_bV_cO_x, Ba_aCu_bTi_cO_x, Ca_aCe_bZr_cO_x, Co_aNi_bTi_cO_x, Co_aNi_bZr_cO_x, Co_aPb_bSn_cO_x, Co_aPb_bZn_cO_x, Cr_aSr_bTi_cO_x, Cu_aFe_bMn_cO_x, Cu_aLa_bSr_cO_x, Fe_aNb_bTi_cO_x, Fe_aPb_bZn_cO_x, Fe_aSr_bTi_cO_x, Fe_aTa_bTi_cO_x, Fe_aW_bZr_cO_x, Ga_aTi_bZn_cO_x, La_aMn_bNa_cO_x, La_aMn_bSr_cO_x, Mn_aSr_bTi_cO_x, Mo_aPb_bZn_cO_x, Nb_aSr_bTi_cO_x, Nb_aSr_bWcO_x, Nb_aTi_bZn_cO_x, Ni_aSr_bTi_cO_x, Sn_aW_bZn_cO_x, Sr_aTi_bV_cO_x, Sr_aTi_bZn_cO_x, or Ti_aW_bZr_cO_x;

a, b, and c are each independently in the range of about 0.0005 to about 1, provided that a+b+c=1; and

x is a number sufficient so that the oxygen present balances the charges of the other elements in the compound.

14. A method according to claim 10 wherein the chemo/electro-active materials comprise first and second chemo/electro-active materials selected from the pairings in the group consisting of

(i) the first material is M¹O_x, and the second material is M¹_aM²_bO_x;

(ii) the first material is M¹O_x, and the second material is M¹_aM²_bM³_cO_x;

(iii) the first material is M¹_aM²_bO_x, and the second material is M¹_aM²_bM³_cO_x;

(iv) the first material is a first M¹O_x, and the second material is a second M¹O_x;

(v) the first material is a first M¹_aM²_bO_x, and the second material is a second M¹_aM²_bO_x; and

(vi) the first material is a first M¹_aM²_bM³_cO_x, and the second material is a second M¹_aM²_bM³_cO_x;

wherein

M¹ is selected from the group consisting of Ce, Co, Cu, Fe, Ga, Nb, Ni, Pr, Ru, Sn, Ti, Tm, W, Yb, Zn, and Zr;

M² and M³ are each independently selected from the group consisting of Al, Ba, Bi, Ca, Cd, Ce, Co, Cr, Cu, Fe, Ga, Ge, In, K, La, Mg, Mn, Mo, Na, Nb, Ni, Pb, Pr, Rb, Ru, Sb, Sc, Si, Sn, Sr, Ta, Ti, Tm, V, W, Y, Yb, Zn, and Zr, but M² and M³ are not the same in M¹_aM²_bM³_cO_x;

a, b and c are each independently about 0.0005 to about 1, provided that a+b+c=1; and

x is a number sufficient so that the oxygen present balances the charges of the other elements in the compound.

15. A method for analyzing at least one individual gas component in a multi-component gas mixture, comprising:

(a) providing an array of at least two chemo/electro-active materials, each chemo/electro-active material having a different electrical response characteristic upon exposure at a selected temperature to the individual gas component than each of the other chemo/electro-active materials, the electrical response characteristic of each material being quantifiable as a value, wherein the response value of at least one material is constant or varies by no more than about twenty percent during exposure of the material to an individual gas component at the selected temperature for a period of at least about one minute;

(b) heating the array to a temperature above 500°

C.;

(c) determining the electrical response value of each chemo/electro-active material upon exposure of the array to the gas mixture;

(d) inputting the electrical responses of the chemo/electro-active materials, but not a baseline response value, a comparison response value or a reference gas value, to a pattern recognition technique; and

(e) performing an analysis of the individual gas component from the inputs in step (d).

16. A method according to claim 15 wherein the array is situated within the gas mixture, which has a temperature of about 400°

C. or more.

17. A method according to claim 15 wherein the gas mixture is an emission from a combustion process.

18. A method according to claim 15 wherein the analysis performed comprises calculating the concentration within the gas mixture of the individual gas component.

19. A method according to claim 15 wherein the array is situated in the gas mixture, which has a temperature of less than about 400°

C., and the array has a substantially constant temperature above 500°

C.

20. A method according to claim 15 wherein the component gases in the mixture are not separated.

21. A method according to claim 15 wherein at least one chemo/electro-active material, when at a temperature of about 400°

C. or more, (i) has an electrical resistivity in the range of about 1 ohm-cm to about 10⁵ ohm-cm, and (ii) exhibits a change in electrical resistance of at least about 0.1 percent upon exposure of the material to an analyte gas component, as compared to the resistance before exposure.

22. A method according to claim 15 wherein the gas mixture comprises one or more members of the group consisting of oxygen, carbon monoxide, a nitrogen oxide, a hydrocarbon, CO₂, H₂S, sulfur dioxide, a halogen, hydrogen, water vapor, ammonia, alcohol, a solvent vapor, an ether, a ketone, an aldehyde, a carbonyl, and a microorganism.

23. A method according to claim 15 wherein the gas mixture comprises one or more members of the group consisting of oxygen, a nitrpgen oxide, a hydrocarbon, and ammonia.

24. A method according to claim 15 wherein the gas mixture comprises one or more members of the group consisting of a nitrogen oxide and ammonia.

25. A method according to claim 15 wherein the gas mixture comprises one or more members of the group consisting of oxygen and a hydrocarbon.

26. A method according to claim 15 wherein the gas mixture is provided from a manufacturing process, a waste stream, environmental monitoring, or a medical, agricultural, food or beverage operation.

27. A method according to claim 15 lwherein at least one chemo/electro-active material is a metal oxide.

28. A method according to claim 27 wherein the chemo/electro-active materials comprise one or more members of the group consisting of M¹O_x, M¹_aM²_bO_x, and M¹_aM²_bM³_cO_x wherein

M¹, M² and M³ are metals that form stable oxides when fired in the presence of oxygen above 500°

C.;

M¹ is selected from Periodic Groups 2-15 and the lanthanide group;

M² and M³ are independently selected from Periodic Groups 1-15 and the larithanide group;

a, b, and c are each independently in the range of about 0.0005 to about 1, provided that a+b+c=1; and

x is a number sufficient so that the oxygen present balances the charges of the other elements in the compound.

29. A method according to claim 27 wherein the chemo/electro-active materials comprise one or more members of the group consisting of M¹O_x, M¹_aM²_bO_x, and M¹_aM²_bM³_cO_x wherein

M¹ is selected from the group consisting of Ce, Go, Cu, Fe, Ga, Nb, Ni, Pr, Ru, Sn, Ti, Tm, W, Yb, Zn, and Zr;

M² and M³ are each independently selected from the group consisting of Al, Ba, Bi, Ca, Cd, Ce, Co, Cr, Cu, Fe, Ga, Ge, In, K, La, Mg, Mn, Mo, Na, Nb, Ni, Pb, Pr, Rb, Ru, Sb, Sc, Si, Sn, Sr, Ta, Ti, Tm, V, W, Y, Yb, Zn, and Zr, but M² and M³ are not the same in M¹_aM²_bM³_cO_x;

a, b, and c are each independently in the range of about 0.0005 to about 1, provided that a+b+c=1; and

x is a number sufficient so that the oxygen present balances the charges of the other elements in the compound.

30. A method according to claim 27 wherein the chemo/electro-active materials comprise one or more members of the group consisting of M¹O_x, M¹_aM²_bO_x, and M¹_aM²_bM³_cO_x wherein M¹O_x is selected from the group consisting of Ce_aO_x, CoO_x, CuO_x, FeO_x, GaO_x, NbO_x, NiO_x, PrO_x, RuO_x, SnO_x, Ta_aO_x, TiO_x, TmO_x, WO_x, YbO_x, ZnO_x, ZrO_x, SnO_x with Ag additive, ZnO_x with Ag additive, TiO_x with Pt additive, ZnO_x with frit additive, NiO_x with frit additive, SnO_x with frit additive, or WO_x with frit additive;

M¹_aM²_bO_x is selected from the group consisting of Al_aCr_bO_x, Al_aFe_bO_x, Al_aMg_bO_x, Al_aNi_bO_x, Al_aTi_bO_x, Al_aV_bO_x, Ba_aCu_bO_x, Ba_aSn_bO_x, Ba_aZn_bO_x, Bi_aRu_bO_x, Bi_aSn_bO_x, Bi_aZn_bO_x, Ca_aSn_bO_x, Ca_aZn_bO_x, Cd_aSn_bO_x, Cd_aZn_bO_x, Ce_aFe_bO_x, Ce_aNb_bO_x, Ce_aTi_bO_x, Ce_aV_bO_x, Co_aCu_bO_x, Co_aGe_bO_x, Co_aLa_bO_x, Co_aMg_bO_x, Co_aNb_bO_x, Co_aPb_bO_x, Co_aSn_bO_x, Co_aV_bO_x, Co_aW_bO_x, Co_aZn_bO_x, Cr_aCu_bO_x, Cr_aLa_bO_x, Cr_aMn_bO_x, Cr_aNi_bO_x, Cr_aSi_bO_x, Cr_aTi_bO_x, Cr_aY_bO_x, Cr_aZn_bO_x, Cu_aFe_bO_x, Cu_aGa_bO_x, Cu_aLa_bO_x, Cu_aNa_bO_x, Cu_aNi_bO_x, Cu_aPb_bO_x, Cu_aSn_bO_x, Cu_aSr_bO_x, Cu_aTi_bO_x, Cu_aZn_bO_x, Cu_aZr_bO_x, Fe_aGa_bO_x, Fe_aLa_bO_x, Fe_aMo_bO_x, Fe_aNb_bO_x, Fe_aNi_bO_x, Fe_aSn_bO_x, Fe_aTi_bO_x, Fe_aW_bO_x, Fe_aZn_bO_x, Fe_aZr_bO_x, Ga_aLa_bO_x, Ga_aSn_bO_x, Ge_aNb_bO_x, Ge_aTi_bO_x, In_aSn_bO_x, K_aNb_bO_x, Mn_aNb_bO_x, Mn_aSn_bO_x, Mn_aTi_bO_x, Mn_aY_bO_x, Mn_aZn_bO_x, Mo_aPb_bO_x, Mo_aRb_bO_x, Mo_aSn_bO_x, Mo_aTi_bO_x, Mo_aZn_bO_x, Nb_aNi_bO_x, Nb_aNi_bO_x, Nb_aSr_bO_x, Nb_aTi_bO_x, Nb_aW_bO_x, Nb_aZr_bO_x, Ni_aSi_bO_x, Ni_aSn_bO_x, Ni_aY_bO_x, Ni_aZn_bO_x, Ni_aZr_bO_x, Pb_aSn_bO_x, Pb_aZn_bO_x, Rb_aW_bO_x, Ru_aSn_bO_x, Ru_aW_bO_x, Ru_aZn_bO_x, Sb_aSn_bO_x, Sb_aZn_bO_x, Sc_aZr_bO_x, Si_aSn_bO_x, Si_aTi_bO_x, Si_aW_bO_x, Si_aZn_bO_x, Sn_aTa_bO_x, Sn_aTi_bO_x, Sn_aW_bO_x, Sn_aZn_bO_x, Sn_aZr_bO_x, Sr_aTi_bO_x, Ta_aTi_bO_x, Ta_aZn_bO_x, Ta_aZr_bO_x, Ti_aV_bO_x, Ti_aW_bO_x, Ti_aZn_bO_x, Ti_aZr_bO_x, VaZn_bO_x, V_aZr_bO_x, W_aZn_bO_x, W_aZr_bO_x, Y_aZr_bO_x, Zn_aZr_bO_x, Al_aNi_bO_x with frit additive, Cr_aTi_bO_x with frit additive, Fe_aNi_bO_x with frit additive, Fe_aTi_bO_x with fit additive, Nb_aTi_bO_x with frit additive, Nb_aW_bO_x with frit additive, Ni_aZn_bO_x with frit additive, Ni_aZr_bO_x with frit additive, or Ta_aTi_bO_x with frit additive; and

M¹_aM²_bM³_cO_x is selected from the group consisting of Al_aMg_bZn_cO_x, Al_aSi_bV_cO_x, Ba_aCu_bTi_cO_x, Ca_aCe_bZr_cO_x, Co_aNi_bTi_cO_x, Co_aNi_bZr_cO_x, Co_aPb_bSn_cO_x, Co_aPb_bZn_cO_x, Cr_aSr_bTi_cO_x, Cu_aFe_bMn_cO_x, Cu_aLa_bSr_cO_x, Fe_aNb_bTi_cO_x, Fe_aPb_bZn_cO_x, Fe_aSr_bTi_cO_x, Fe_aTa_bTi_cO_x, Fe_aW_bZr_cO_x, Ga_aTi_bZn_cO_x, La_aMn_bNa_cO_x, La_aMn_bSr_cO_x, Mn_aSr_bTi_cO_x, Mo_aPb_bZn_cO_x, Nb_aSr_bTi_cO_x, Nb_aSr_bW_cO_x, Nb_aTi_bZn_cO_x, Ni_aSr_bTi_cO_x, Sn_aW_bZn_cO_x, Sr_aTi_bV_cO_x, Sr_aTi_bZn_cO_x, or Ti_aW_bZr_cO_x;

a, b, and c are each independently in the range of about 0.0005 to about 1, provided that a+b+c=1; and

x is a number sufficient so that the oxygen present balances the charges of the other elements in the compound.

31. A method according to claim 27 wherein the chemo/electro-active materials comprise first and second chemo/electro-active materials selected from the pairings in the group consisting of

(i) the first material is M¹ O_x, and the second material is M¹_aM²_bO_x;

(ii) the first material is M¹O_x, and the second material is M¹_aM²_bM³_cO_x;

(iii) the first material is M¹_aM²_bO_x, and the second material is M¹_aM²_bM³_cO_x;

(iv) the first material is a first M¹O_x, and the second material is a second M¹O_x;

(v) the first material is a first M¹_aM²_bO_x, and the second material is a second M¹_aM²_bO_x; and

(vi) the first material is a first M¹_aM²_bM³_cO_x, and the second material is a second M¹_aM²_bM³_cO_x;

wherein M¹ is selected from the group consisting of Ce, Co, Cu, Fe, Ga, Nb, Ni, Pr, Ru, Sn, Ti, Tm, W, Yb, Zn, and Zr;

M² and M³ are each independently selected from the group consisting of Al, Ba, Bi, Ca, Cd, Ce, Co, Cr, Cu, Fe, Ga, Ge, In, K, La, Mg, Mn, Mo, Na, Nb, Ni, Pb, Pr, Rb, Ru, Sb, Sc, Si, Sn, Sr, Ta, Ti, Tm, V, W, Y, Yb, Zn, and Zr, but M² and M³ are not the same m M¹_aM²_bM³_cO_x;

a, b and c are each independently about 0.0005 to about 1, provided that a+b+c=1; and

x is a number sufficient so that the oxygen present balances the charges of the other elements in the compound.

32. A method according to claim 15 wherein the electrical response is selected from the group consisting of resistance, nnpedance, capacitance, voltage or current.

33. A method for directly sensing gas components in a multi-component gas system, comprising

(a) exposing a chemical sensor comprising an array of at least two chemo/electro-active materials to a multi-component gas system;

(b) heating the array to a temperature above 500°

C.;

(c) detecting a response;

(d) directly measuring the response of each chemo/electro-active material;

(e) inputting the electrical responses of the chemo/electro-active materials, but not a baseline response value, a cornparison response value or a reference gas value, to a pattern recognition technique; and

(f) detecting the presence of and/or calculating the concentration of one or more individual analyte gas components in the system from the inputs in step (e).

34. A method according to claim 33 wherein at least one chemo/electro-active material, when at a temperature of about 400°

C. or more, (i) has an electrical resistivity in the range of about 1 ohm-cm to about 10⁵ ohm-cm, and (ii) exhibits a change in electrical resistance of at least about 0.1 percent upon exposure of the material to an individual gas component, as compared to the resistance before exposure.

35. A method according to claim 33 wherein the electrical response characteristic of each material upon exposure to the gas mixture at a selected temperature is quantifiable as a value, and the response value of at least one material is constant or varies by no more than about twenty percent during exposure of the material to an analyte gas component at the selected temperature for a period of at least about one minute.

36. A method according to claim 33 wherein the electrical response is selected from the group consisting of resistance, impedance, capacitance, voltage or current.

37. A method according to claim 33 wherein the array is situated within the gas mixture, which has a temperature of about 400°

C. or more.

38. A method according to claim 33 wherein the array is situated in the gas mixture, which has a temperature of less than about 400°

C., and the array has a substantially constant temperature above 500°

C.

39. A method according to claim 33 wherein the component gases in the gas mixture are not separated.

40. A method according to claim 33 wherein the analysis performed comprises calculating the concentration within the gas mixture of the individual gas component.

41. A method according to claim 33 wherein gas mixture comprises one or more members of the group consisting of oxygen, carbon monoxide, a nitrogen oxide, a hydrocarbon, CO₂, H₂S, sulfur dioxide, a halogen, hydrogen, water vapor, ammonia, alcohol, a solvent vapor, an ether, a ketone, an aldehyde, a carbonyl, and a microorganism.

42. A method according to claim 33 wherein the gas mixture comprises one or more members of the group consisting of oxygen, a nitrogen oxide, a hydrocarbon, and ammonia.

43. A method according to claim 33 wherein the gas mixture comprises one or more members of the group consisting of a nitrogen oxide and ammonia.

44. A method according to claim 33 wherein the gas mixture comprises one or more members of the group consisting of oxygen and a hydrocarbon.

45. A method according to claim 33 wherein the gas mixture is an emission from a combustion process.

46. A method according to claim 33 wherein the gas mixture is provided from a manufacturing process, a waste stream, environmental monitoring, or a medical, agricultural, food or beverage operation.

47. A method according to claim 33 wherein at least one chemo/electro-active material is a metal oxide.

48. A method according to claim 47 wherein the chemo/electro-active materials comprise one or more members of the group consisting of M¹O_x, M¹_aM²_bO_x, and M¹_aM²_bM³_cO_x wherein

M¹, M² and M³ are metals that form stable oxides when fired in the presence of oxygen above 500°

C.;

M¹ is selected from Periodic Groups 2-15 and the lanthanide group;

M² and M³ are independently selected from Periodic Groups 1-15 and the lanthanide group;

a, b, and c are each independently in the range of about 0.0005 to about 1, provided that a+b+c=1; and

x is a number sufficient so that the oxygen present balances the charges of the other elements in the compound.

49. A method according to claim 47 wherein the chemo/electro-active materials comprise one or more members of the group consisting of M¹O_x, M¹_aM²_bO_x, and M¹_aM²_bM³_cO_x wherein

M¹ is selected from the group consisting of Ce, Co, Cu, Fe, Ga, Nb, Ni, Pr, Ru, Sn, Ti, Tm, W, Yb, Zn, and Zr;

M² and M³ are each independently selected from the group consisting of Al, Ba, Bi, Ca, Cd, Ce, Co, Cr, Cu, Fe, Ga, Ge, In, K, La, Mg, Mn, Mo, Na, Nb, Ni, Pb, Pr, Rb, Ru, Sb, Sc, Si, Sn, Sr, Ta, Ti, Tm, V, W, Y, Yb, Zn, and Zr, but M² and M³ are not the same in M¹_aM²_bM³_cO_x;

a, b, and c are each independently in the range of about 0.0005 to about 1, provided that a+b+c=1; and

x is a number sufficient so that the oxygen present balances the charges of the other elements in the compound.

50. A method according to claim 47 wherein the chemo/electro-active materials comprise one or more members of the group consisting of M¹O_x, M¹_aM²_bO_x, and M¹_aM²_bM³_cO_x wherein

M¹O_x is selected from the group consisting of Ce_aO_x, CoO_x, CuO_x, FeO_x, GaO_x, NbO_x, NiO_x, PrO_x, RuO_x, SnO_x, Ta_aO_x, TiO_x, TmO_x, WO_x, YbO_x, ZnO_x, ZrO_x, SnO_x with Ag additive, ZnO_x with Ag additive, TiO_x with Pt additive, ZnO_x with frit additive, NiO_x with frit additive, SnO_x with frit additive, or WO_x with frit additive;

M¹_aM²_bO_x is selected from the group consisting of Al_aCr_bO_x, Al_aFe_bO_x, Al_aMg_bO_x, Al_aNi_bO_x, Al_aTi_bO_x, Al_aV_bO_x, Ba_aCu_bO_x, Ba_aSn_bO_x, Ba_aZn_bO_x, Bi_aRu_bO_x, Bi_aSn_bO_x, Bi_aZn_bO_x, Ca_aSn_bO_x, Ca_aZn_bO_x, Cd_aSn_bO_x, Cd_aZn_bO_x, Ce_aFe_bO_x, Ce_aNb_bO_x, Ce_aTi_bO_x, Ce_aV_bO_x, Co_aCu_bO_x, Co_aGe_bO_x, Co_aLa_bO_x, Co_aMg_bO_x, Co_aNb_bO_x, Co_aPb_bO_x, Co_aSn_bO_x, Co_aV_bO_x, Co_aW_bO_x, Co_aZn_bO_x, Cr_aCu_bO_x, Cr_aLa_bO_x, Cr_aMn_bO_x, Cr_aNi_bO_x, Cr_aSi_bO_x, Cr_aTi_bO_x, Cr_aY_bO_x, Cr_aZn_bO_x, Cu_aFe_bO_x, Cu_aGa_bO_x, Cu_aLa_bO_x, Cu_aNa_bO_x, Cu_aNi_bO_x, Cu_aPb_bO_x, Cu_aSn_bO_x, Cu_aSr_bO_x, Cu_aTi_bO_x, Cu_aZn_bO_x, Cu_aZr_bO_x, Fe_aGa_bO_x, Fe_aLa_bO_x, Fe_aMo_bO_x, Fe_aNb_bO_x, Fe_aNi_bO_x, Fe_aSn_bO_x, Fe_aTi_bO_x, Fe_aW_bO_x, Fe_aZn_bO_x, Fe_aZr_bO_x, Ga_aLa_bO_x, Ga_aSn_bO_x, Ge_aNb_bO_x, Ge_aTi_bO_x, In_aSn_bO_x, K_aNb_bO_x, Mn_aNb_bO_x, Mn_aSn_bO_x, Mn_aTi_bO_x, Mn_aY_bO_x, Mn_aZn_bO_x, Mo_aPb_bO_x, Mo_aRb_bO_x, Mo_aSn_bO_x, Mo_aTi_bO_x, Mo_aZn_bO_x, Nb_aNi_bO_x, Nb_aNi_bO_x, Nb_aSr_bO_x, Nb_aTi_bO_x, Nb_aW_bO_x, Nb_aZr_bO_x, Ni_aSi_bO_x, Ni_aSn_bO_x, Ni_aY_bO_x, Ni_aZn_bO_x, Ni_aZr_bO_x, Pb_aSn_bO_x, Pb_aZn_bO_x, Rb_aW_bO_x, Ru_aSn_bO_x, Ru_aW_bO_x, Ru_aZn_bO_x, Sb_aSn_bO_x, Sb_aZn_bO_x, Sc_aZr_bO_x, Si_aSn_bO_x, Si_aTi_bO_x, Si_aW_bO_x, Si_aZn_bO_x, Sn_aTa_bO_x, Sn_aTi_bO_x, Sn_aW_bO_x, Sn_aZn_bO_x, Sn_aZr_bO_x, Sr_aTi_bO_x, Ta_aTi_bO_x, Ta_aZn_bO_x, Ta_aZr_bO_x, Ti_aV_bO_x, Ti_aW_bO_x, Ti_aZn_bO_x, Ti_aZr_bO_x, V_aZn_bO_x, V_aZr_bO_x, W_aZn_bO_x, W_aZr_bO_x, Y_aZr_bO_x, Zn_aZr_bO_x, Al_aNi_bO_x with frit additive, Cr_aTi_bO_x with frit additive, Fe_aNi_bO_x with frit additive, Fe_aTi_bO_x with frit additive, Nb_aTi_bO_x with frit additive, Nb_aW_bO_x with frit additive, Ni_aZn_bO_x with frit additive, Ni_aZr_bO_x with frit additive, or Ta_aTi_bO_x with frit additive; and

M¹_aM²_bM³_cO_x is selected from the group consisting of Al_aMg_bZn_cO_x, Al_aSi_bV_cO_x, Ba_aCu_bTi_cO_x, Ca_aCe_bZr_cO_x, Co_aNi_bTi_cO_x, Co_aNi_bZr_cO_x, Co_aPb_bSn_cO_x, Co_aPb_bZn_cO_x, Cr_aSr_bTi_cO_x, Cu_aFe_bMn_cO_x, Cu_aLa_bSr_cO_x, Fe_aNb_bTi_cO_x, Fe_aPb_bZn_cO_x, Fe_aSr_bTi_cO_x, Fe_aTa_bTi_cO_x, Fe_aW_bZr_cO_x, Ga_aTi_bZn_cO_x, La_aMn_bNa_aO_x, La_aMn_bSr_cO_x, Mn_aSr_bTi_cO_x, Mo_aPb_bZn_cO_x, Nb_aSr_bTi_cO_x, Nb_aSr_bW_cO_x, Nb_aTi_bZn_cO_x, Ni_aSr_bTi_cO_x, Sn_aW_bZn_cO_x, Sr_aTi_bV_cO_x, Sr_aTi_bZn_cO_x, or Ti_aW_bZr_cO_x;

a, b, and c are each independently in the range of about 0.0005 to about 1, provided that a+b+c=1; and

x is a number sufficient so that the oxygen present balances the charges of the other elements in the compound.

51. A method according to claim 47 wherein the chemo/electro-active materials comprise first and second chemo/electro-active materials selected from the pairings in the group consisting of

(i) the first material is M¹O_x, and the second material is M¹_aM²_bO_x;

(ii) the first material is M¹_x, and the second material is M¹_aM²_bM³_cO_x;

(iii) the first material is M¹_aM²_bO_x, and the second material is M¹_aM²_bM³_cO_x;

(iv) the first material is a first M¹O_x, and the second material is a second M¹O_x;

(v) the first material is a first M¹_aM²_bO_x, and the second material is a second M¹_aM²_bO_x; and

(vi) the first material is a first M¹_aM²_bM³_cO_x, and the second material is a second M¹_aM²_bM³_cO_x;

wherein

M¹ is selected from the group consisting of Ce, Co, Cu, Fe, Ga, Nb, Ni, Pr, Ru, Sn, Ti, Tm, W, Yb, Zn, and Zr;

M² and M³ are each independently selected from the group consisting of Al, Ba, Bi, Ca, Cd, Ce, Co, Cr, Cu, Fe, Ga, Ge, In, K, La, Mg, Mn, Mo, Na, Nb, Ni, Pb, Pr, Rb, Ru, Sb, Sc, Si, Sn, Sr, Ta, Ti, Tm, V, W, Y, Yb, Zn, and Zr, but M² and M³ are not the same in M¹_aM²_bM³_cO_x;

a, b and c are each independently about 0.0005 to about 1, provided that a+b+c1; and

x is a number sufficient so that the oxygen present balances the charges of the other elements in the compound.

52. A method for directly sensing gas components in a multi-component gas system, comprising

(a) exposing a chemical sensor comprising an array of at least two chemo/electro-active materials to a multi-component gas system;

(b) heating the array to a temperature above 500°

C.;

(c) detecting a response;

(d) directly measuring the response of each chemo/electro-active material;

(e) inputting only the electrical responses of the chemo/electro-active materials to a pattern recognition technique; and

(f) detecting the presence of and/or calculating the concentration of one or more individual analyte gas components in the system from the inputs in step (e).

53. A method according to claim 52 wherein at least one chemo/electro-active material, when at a temperature of about 400°

C. or more, (i) has an electrical resistivity in the range of about 1 ohm-cm to about 10⁵ ohm-cm, and (ii) exhibits a change in electrical resistance of at least about 0.1 percent upon exposure of the material to an individual gas component, as compared to the resistance before exposure.

54. A method according to claim 52 wherein the electrical response characteristic of each material upon exposure to the gas mixture at a selected temperature is quantifiable as a value, and the response value of at least one material is constant or varies by no more than about twenty percent during exposure of the material to an analyte gas component at the selected temperature for a period of at least about one minute.

55. A method according to claim 52 wherein the electrical response is selected from the group consisting of resistance, impedance, capacitance, voltage or current.

56. A method according to claim 52 wherein the array is situated within the gas mixture, which has a temperature of about 400°

C. or more.

57. A method according to claim 52 wherein the array is situated in the gas mixture, which has a temperature of less than about 400°

C., arid the array has a substantially constant temperature above 500°

C.

58. A method according to claim 52 wherein the component gases in the gas mixture are not separated.

59. A method according to claim 52 wherein the analysis performed comprises calculating the concentration within the gas mixture of the individual gas component.

60. A method according to claim 52 wherein the gas mixture comprises one or more members of the group consisting of oxygen, carbon monoxide, a nitrogen oxide, a hydrocarbon, CO₂, H₂S, sulfur dioxide, a halogen, hydrogen, water vapor, ammonia, alcohol, a solvent vapor, an ether, a ketone, an aldehyde, a carbonyl, and a microorganism.

61. A method according to claim 52 wherein the gas mixture comprises one or more members of the group consisting of oxygen, a nitrogen oxide, a hydrocarbon, and ammonia.

62. A method according to claim 52 wherein the gas mixture comprises one or more members of the group consisting of a nitrogen oxide and ammonia.

63. A method according to claim 52 wherein the gas mixture comprises one or more members of the group consisting of oxygen and a hydrocarbon.

64. A method according to claim 52 wherein the gas mixture is an emission from a combustion process.

65. A method according to claim 52 wherein the gas mixture is provided from a manufacturing process, a waste stream, environmental monitoring, or a medical, agricultural, food or beverage operation.

66. A method according to claim 52 wherein at least one chemo/electro-active material is a metal oxide.

67. A method according to claim 66 wherein the chemo/electro-active materials comprise one or more members of the group consisting of M¹O_x, M¹_aM²_bO_x, and M¹_aM²_bM³_cO_x wherein

M¹, M² and M³ are metals that form stable oxides when fired in the presence of oxygen above 500°

C.;

M¹ is selected from Periodic Groups 2-15 and the lanthanide group;

M² and M³ are independently selected from Periodic Groups 1-15 and the lanthanide group;

a, b, and c are each independently in the range of about 0.0005 to about 1, provided that a+b+c=1; and

x is a number sufficient so that the oxygen present balances the charges of the other elements in the compound.

68. A method according to claim 66 wherein the chemo/electro-active materials comprise one or more members of the group consisting of M¹O_x, M¹_aM²_bO_x, and M¹_aM²_bM³_cO_x wherein

M¹ is selected from the group consisting of Ce, Co, Cu, Fe, Ga, Nb, Ni, Pr, Ru, Sn, Ti, Tm, W, Yb, Zn, and Zr;

M² and M³ are each independently selected from the group consisting of Al, Ba, Bi, Ca, Cd, Ce, Co, Cr, Cu, Fe, Ga, Ge, In, K, La, Mg, Mn, Mo, Na, Nb, Ni, Pb, Pr, Rb, Ru, Sb, Sc, Si, Sn, Sr, Ta, Ti, Tm, V, W, Y, Yb, Zn, and Zr, but M² and M³ are not the same in M¹_aM²_bM³_cO_x;

a, b, and c are each independently in the range of about 0.0005 to about 1, provided that a+b+c=1; and

x is a number sufficient so that the oxygen present balances the charges of the other elements in the compound.

69. A method according to claim 66 erein the chemo/electro-active materials comprise one or more members of the group consisting of M¹O_x, M¹_aM²_bO_x, and M¹_aM²_bM³_cO_x wherein

M¹ O_x is selected from the group consisting of Ce_aO_x, CoO_x, CuO_x, FeO_x, GaO_x, NbO_x, NiO_x, PrO_x, RuO_x, SnO_x, Ta_aO_x, TiO_x, TmO_x, WO_x, YbO_x, ZnO_x, ZrO_x, SnO_x with Ag additive, ZnO_x with Ag additive, TiO_x with Pt additive, ZnO_x with frit additive, NiO_x with frit additive, SnO_x with frit additive, or WO_x with frit additive;

M¹_aM²_bO_x is selected from the group consisting of Al_aCr_bO_x, Al_aFe_bO_x, Al_aMg_bO_x, Al_aNi_bO_x, Al_aTi_bO_x, Al_aV_bO_x, Ba_aCu_bO_x, Ba_aSn_bO_x, Ba_aZn_bO_x, Bi_aRu_bO_x, Bi_aSn_bO_x, Bi_aZn_bO_x, Ca_aSn_bO_x, Ca_aZn_bO_x, Cd_aSn_bO_x, Cd_aZn_bO_x, Ce_aFe_bO_x, Ce_aNb_bO_x, Ce_aTi_bO_x, Ce_aV_bO_x, Co_aCu_bO_x, Co_aGe_bO_x, Co_aLa_bO_x, Co_aMg_bO_x, Co_aNb_bO_x, Co_aPb_bO_x, Co_aSn_bO_x, Co_aV_bO_x, Co_aW_bO_x, Co_aZn_bO_x, Cr_aCu_bO_x, Cr_aLa_bO_x, Cr_aMn_bO_x, Cr_aNi_bO_x, Cr_aSi_bO_x, Cr_aTi_bO_x, Cr_aY_bO_x, Cr_aZn_bO_x, Cu_aFe_bO_x, Cu_aGa_bO_x, Cu_aLa_bO_x, Cu_aNa_bO_x, Cu_aNi_bO_x, Cu_aPb_bO_x, Cu_aSn_bO_x, Cu_aSr_bO_x, Cu_aTi_bO_x, Cu_aZn_bO_x, Cu_aZr_bO_x, Fe_aGa_bO_x, Fe_aLa_bO_x, Fe_aMo_bO_x, Fe_aNb_bO_x, Fe_aNi_bO_x, Fe_aSn_bO_x, Fe_aTi_bO_x, Fe_aW_bO_x, Fe_aZn_bO_x, Fe_aZr_bO_x, Ga_aLa_bO_x, Ga_aSn_bO_x, Ge_aNb_bO_x, Ge_aTi_bO_x, In_aSn_bO_x, K_aNb_bO_x, Mn_aNb_bO_x, Mn_aSn_bO_x, Mn_aTi_bO_x, Mn_aY_bO_x, Mn_aZn_bO_x, Mo_aPb_bO_x, Mo_aRb_bO_x, Mo_aSn_bO_x, Mo_aTi_bO_x, Mo_aZn_bO_x, Nb_aNi_bO_x, Nb_aNi_bO_x, Nb_aSr_bO_x, Nb_aTi_bO_x, Nb_aW_bO_x, Nb_aZr_bO_x, Ni_aSi_bO_x, Ni_aSn_bO_x, Ni_aY_bO_x, Ni_aZn_bO_x, Ni_aZr_bO_x, Pb_aSn_bO_x, Pb_aZn_bO_x, Rb_aW_bO_x, Ru_aSn_bO_x, Ru_aW_bO_x, Ru_aZn_bO_x, Sb_aSn_bO_x, Sb_aZn_bO_x, Sc_aZr_bO_x, Si_aSn_bO_x, Si_aTi_bO_x, Si_aW_bO_x, Si_aZn_bO_x, Sn_aTa_bO_x, Sn_aTi_bO_x, Sn_aW_bO_x, Sn_aZn_bO_x, Sn_aZr_bO_x, Sr_aTi_bO_x, Ta_aTi_bO_x, Ta_aZn_bO_x, Ta_aZr_bO_x, Ti_aV_bO_x, Ti_aW_bO_x, Ti_aZn_bO_x, Ti_aZr_bO_x, V_aZn_bO_x, V_aZr_bO_x, W_aZn_bO_x, W_aZr_bO_x, Y_aZr_bO_x, Zn_aZr_bO_x, Al_aNi_bO_x with frit additive, Cr_aTi_bO_x with frit additive, Fe_aNi_bO_x with frit additive, Fe_aTi_bO_x with frit additive, Nb_aTi_bO_x with frit additive, Nb_aW_bO_x with frit additive, Ni_aZn_bO_x with frit additive, Ni_aZr_bO_x with frit additive, or Ta_aTi_bO_x with frit additive; and

M¹_aM²_bM³_cO_x is selected from the group consisting of Al_aMg_bZn_cO_x, Al_aSi_bV_cO_x, Ba_aCu_bTi_cO_x, Ca_aCe_bZr_cO_x, Co_aNi_bTi_cO_x, Co_aNi_bZr_cO_x, Co_aPb_bSn_cO_x, Co_aPb_bZn_cO_x, Cr_aSr_bTi_cO_x, Cu_aFe_bMn_cO_x, Cu_aLa_bSr_cO_x, Fe_aNb_bTi_cO_x, Fe_aPb_bZn_cO_x, Fe_aSr_bTi_cO_x, Fe_aTa_bTi_cO_x, Fe_aW_bZr_cO_x, Ga_aTi_bZn_cO_x, La_aMn_bNa_cO_x, La_aMn_bSr_cO_x, Mn_aSr_bTi_cO_x, Mo_aPb_bZn_cO_x, Nb_aSr_bTi_cO_x, Nb_aSr_bW_cO_x, Nb_aTi_bZn_cO_x, Ni_aSr_bTi_cO_x, Sn_aW_bZn_cO_x, Sr_aTi_bV_cO_x, Sr_aTi_bZn_cO_x, or Ti_aW_bZr_cO_x;

a, b, arid c are each independently in the range of about 0.0005 to about 1, provided that a+b+c=1; and

x is a number sufficient so that the oxygen present balances the charges of the other elements in the compound.

70. A method according to claim 66 wherein the chemo/electro-active materials comprise first and second chemo/electro-active materials selected from the pairings in the group consisting of

(i) the first material is M¹O_x, and the second material is M¹_aM²_bO_x;

(ii) the first material is M¹O_x, and the second material is M¹_aM²_bM³_cO_x,

(iii) the first material is M¹_aM²_bO_x, and the second material is M¹_aM²_bM³_cO_x;

(iv) the first material is a first M¹O_x, and the second material is a second M¹O_x;

(v) the first material is a first M¹_aM²_bO_x, and the second material is a second M¹_aM²_bO_x; and

(vi) the first material is a first M¹_aM²_bM³_cO_x, and the second material is a second M¹_aM²_bM³_cO_x;

wherein

M¹ is selected from the group consisting of Ce, Co, Cu, Fe, Ga, Nb, Ni, Pr, Ru, Sn, Ti, Tm, W, Yb, Zn, and Zr;

M² and M³ are each independently selected from the group consisting of Al, Ba, Bi, Ca, Cd, Ce, Co, Cr, Cu, Fe, Ga, Ge, In, K, La, Mg, Mn, Mo, Na, Nb, Ni, Pb, Pr, Rb, Ru, Sb, Sc, Si, Sn, Sr, Ta, Ti, Tm, V, W, Y, Yb, Zn, and Zr, but M² and M³ are not the same in M¹_aM²_bM³_cO_x;

a, b and c are each independently about 0.0005 to about 1, provided that a+b+c=1; and

x is a number sufficient so that the oxygen present balances the charges of the other elements in the compound.

71. A method for calculating the concentration of at least two individual analyte gas components in a multi-component gas mixture having a temperature of about 400°

C. or more, comprising;

(a) providing within the gas mixture an array of at least three chemo/electro-active materials, each chemo/electro-active material having a different electrical response characteristic upon exposure to each of the individual analyte gas components than each of the other chemo/electro-active materials, wherein at least one chemo/electro-active material, when at a temperature of about 400°

C. or more,

(i) has an electrical resistivity in the range of about 1 ohm-cm to about 10⁵ ohm-cm, and

(ii) exhibits a change in electrical resistance of at least about 0.1 percent upon exposure of the material to an analyte gas component, as compared to the resistance before exposure;

(b) heating the array to a temperature above 500°

C.;

(c) determining an electrical response of each chemo/electro-active material upon exposure of the array to the unseparated components of the gas mixture;

(d) inputting only the electrical responses of the chemo/electro-active materials to a pattern recognition technique; and

(e) calculating the concentration of each of the individual analyte gas components from the inputs in step (d).

72. A method according to claim 71 wherein the electrical response characteristic of each material upon exposure to the gas mixture at a selected temperature is quantifiable as a value, and the response value of at least one material is constant or varies by no more than about twenty percent during exposure of the material to an analyte gas component at the selected temperature for a period of at least about one minute.

73. A method according to claim 71 wherein the electrical response is selected from the group consisting of resistance, impedance, capacitance, voltage or current.

74. A method according to claim 71 wherein the gas mixture comprises one or more members of the group consisting of oxygen, carbon monoxide, a nitrogen oxide, a hydrocarbon, CO₂, H₂S, sulfur dioxide, a halogen, hydrogen, water vapor, ammonia, alcohol, a solvent vapor, an ether, a ketone, an aldehyde, a carbonyl, and a microorganism.

75. A method according to claim 71 wherein the gas mixture comprises one or more members of the group consisting of oxygen, a nitrogen oxide, a hydrocarbon, and ammonia.

76. A method according to claim 71 wherein the gas mixture comprises one or more members of the group consisting of a nitrogen oxide and ammonia.

77. A method according to claim 71 wherein the gas mixture comprises one or more members of the group consisting of oxygen and a hydrocarbon.

78. A method according to claim 71 wherein the gas mixture is an emission from a combustion process.

79. A method according to claim 71 wherein the gas mixture is provided from a manufacturing process, a waste stream, environmental monitoring, or a medical, agricultural, food or beverage operation.

80. A method according to claim 71 wherein at least one chemo/electro-active material is a metal oxide.

81. A method according to claim 80 wherein the chemo/electro-active materials comprise one or more members of the group consisting of M¹O_x, M¹_aM²_bO_x, and M¹_aM²_bM³_cO_x wherein M¹, M² and M³ are metals that form stable oxides when fired in the presence of oxygen above 500°

C.;

M¹ is selected from Periodic Groups 2-15 and the lantharude group;

M² and M³ are independently selected from Periodic Groups 1-15 and the lanthanide group;

a, b, and c are each independently in the range of about 0.0005 to about 1, provided that a+b+c=1; and

x is a number sufficient so that the oxygen present balances the charges of the other elements in the compound.

82. A method according to claim 80 wherein the chemo/electro-active materials comprise one or more members of the group consisting of M¹O_x, M¹_aM²_bO_x, and M¹_aM²_bM³_cO_x wherein

M¹ is selected from the group consisting of Ce, Co, Cu, Fe, Ga, Nb, Ni, Pr, Ru, Sn, Ti, Tm, W, Yb, Zn, and Zr;

M² and M³ are each independently selected from the group consisting of Al, Ba, Bi, Ca, Cd, Ce, Co, Cr, Cu, Fe, Ga, Ge, In, K, La, Mg, Mn, Mo, Na, Nb, Ni, Pb, Pr, Rb, Ru, Sb, Sc, Si, Sn, Sr, Ta, Ti, Tm, V, W, Y, Yb, Zn, and Zr, but M² and M³ are not the same in M¹_aM²_bM³_cO_x;

a, b, and c are each independently in the range of about 0.0005 to about 1, provided that a+b+c=1; and

x is a number sufficient so that the oxygen present balances the charges of the other elements in the compound.

83. A method according to claim 80 wherein the chemo/electro-active materials comprise one or more members of the group consisting of M¹O_x, M¹_aM²_bO_x, and M¹_aM²_bM³_cO_x wherein

M¹O_x is selected from the group consisting of Ce_aO_x, CoO_x, CuO_x, FeO_x, GaO_x, NbO_x, NiO_x, PrO_x, RuO_x, SnO_x, Ta_aO_x, TiO_x, TmO_x, WO_x, YbO_x, ZnO_x, ZrO_x, SnO_x with Ag additive, ZnO_x with Ag additive, TiO_x with Pt additive, ZnO_x with frit additive, NiO_x with frit additive, SnO_x with frit additive, or WO_x with frit additive;

M¹_aM²_bO_x is selected from the group consisting of Al_aCr_bO_x, Al_aFe_bO_x, Al_aMg_bO_x, Al_aNi_bO_x, Al_aTi_bO_x, Al_aV_bO_x, Ba_aCu_bO_x, Ba_aSn_bO_x, Ba_aZn_bO_x, Bi_aRu_bO_x, Bi_aSn_bO_x, Bi_aZn_bO_x, Ca_aSn_bO_x, Ca_aZn_bO_x, Cd_aSn_bO_x, Cd_aZn_bO_x, Ce_aFe_bO_x, Ce_aNb_bO_x, Ce_aTi_bO_x, Ce_aV_bO_x, Co_aCu_bO_x, Co_aGe_bO_x, Co_aLa_bO_x, Co_aMg_bO_x, Co_aNb_bO_x, Co_aPb_bO_x, Co_aSn_bO_x, Co_aV_bO_x, Co_aW_bO_x, Co_aZn_bO_x, Cr_aCu_bO_x, Cr_aLa_bO_x, Cr_aMn_bO_x, Cr_aNi_bO_x, Cr_aSi_bO_x, Cr_aTi_bO_x, Cr_aY_bO_x, Cr_aZn_bO_x, Cu_aFe_bO_x, Cu_aGa_bO_x, Cu_aLa_bO_x, Cu_aNa_bO_x, Cu_aNi_bO_x, Cu_aPb_bO_x, Cu_aSn_bO_x, Cu_aSr_bO_x, Cu_aTi_bO_x, Cu_aZn_bO_x, Cu_aZr_bO_x, Fe_aGa_bO_x, Fe_aLa_bO_x, Fe_aMo_bO_x, Fe_aNb_bO_x, Fe_aNi_bO_x, Fe_aSn_bO_x, Fe_aTi_bO_x, Fe_aW_bO_x, Fe_aZn_bO_x, Fe_aZr_bO_x, Ga_aLa_bO_x, Ga_aSn_bO_x, Ge_aNb_bO_x, Ge_aTi_bO_x, In_aSn_bO_x, K_aNb_bO_x, Mn_aNb_bO_x, Mn_aSn_bO_x, Mn_aTi_bO_x, Mn_aY_bO_x, Mn_aZn_bO_x, Mo_aPb_bO_x, Mo_aRb_bO_x, Mo_aSn_bO_x, Mo_aTi_bO_x, Mo_aZn_bO_x, Nb_aNi_bO_x, Nb_aNi_bO_x, Nb_aSr_bO_x, Nb_aTi_bO_x, Nb_aW_bO_x, Nb_aZr_bO_x, Ni_aSi_bO_x, Ni_aSn_bO_x, Ni_aY_bO_x, Ni_aZn_bO_x, Ni_aZr_bO_x, Pb_aSn_bO_x, Pb_aZn_bO_x, Rb_aW_bO_x, Ru_aSn_bO_x, Ru_aW_bO_x, Ru_aZn_bO_x, Sb_aSn_bO_x, Sb_aZn_bO_x, Sc_aZr_bO_x, Si_aSn_bO_x, Si_aTi_bO_x, Si_aW_bO_x, Si_aZn_bO_x, Sn_aTa_bO_x, Sn_aTi_bO_x, Sn_aW_bO_x, Sn_aZn_bO_x, Sn_aZr_bO_x, Sr_aTi_bO_x, Ta_aTi_bO_x, Ta_aZn_bO_x, Ta_aZr_bO_x, Ti_aV_bO_x, Ti_aW_bO_x, Ti_aZn_bO_x, Ti_aZr_bO_x, V_aZn_bO_x, V_aZr_bO_x, W_aZn_bO_x, W_aZr_bO_x, Y_aZn_aO_x, Zn_aZr_bO_x, Al_aNi_bO_x with frit additive, Cr_aTi_bO_x with frit additive, Fe_aNi_bO_x With frit additive, Fe_aTi_bO_x with frit additive, Nb_aTi_bO_x with frit additive, Nb_aW_bO_x With frit additive, Ni_aZn_bO_x x with frit additive, Ni_aZr_bO_x with frit additive, or Ta_aTi_bO_x with frit additive; and

M¹_aM²_bM³_cO_x is selected from the group consisting of Al_aMg_bZn_cO_x, Al_aSi_bV_cO_x, Ba_aCu_bTi_cO_x, Ca_aCe_bZr_cO_x, Co_aNi_bTi_cO_x, Co_aNi_bZr_cO_x, Co_aPb_bSn_cO_x, Co_aPb_bZn_cO_x, Cr_aSr_bTi_cO_x, Cu_aFe_bMn_cO_x, Cu_aLa_bSr_cO_x, Fe_aNb_bTi_cO_x, Fe_aPb_bZn_cO_x, Fe_aSr_bTi_cO_x, Fe_aTa_bTi_cO_x, Fe_aW_bZr_cO_x, Ga_aTi_bZn_cO_x, La_aMn_bNa_cO_x, La_aMn_bSr_cO_x, Mn_aSr_bTi_cO_x, Mo_aPb_bZn_cO_x, Nb_aSr_bTi_cO_x, Nb_aSr_bW_cO_x, Nb_aTi_bZn_cO_x, Ni_aSr_bTi_cO_x, Sn_aW_bZn_cO_x, Sr_aTi_bV_cO_x, Sr_aTi_bZn_cO_x, or Ti_aW_bZr_cO_x;

a, b, and c are each independently in the range of about 0.0005 to about 1, provided that a+b+c=1; and

x is a number sufficient so that the oxygen present balances the charges of the other elements in the compound.

84. A method according to claim 80 wherein the chemo/electro-active materials comprise first and second chemo/electro-active materials selected from the pairings in the group consisting of

(i) the first material is M¹O_x, and the second material is M¹_aM²_bO_x;

(ii) the first material is M¹O_x, and the second material is M¹_aM²_bM³_cO_x;

(iii) the first material is M¹_aM²_bO_x, and the second material is M¹_aM²_bM³_cO_x;

(iv) the first material is a first M¹O_x, and the second material is a second M¹O_x;

(v) the first material is a first M¹_aM²_bO_x, and the second material is a second M¹_aM²_bO_x; and

(vi) the first material is a first M_aM²_bM³_cO_x, and the second material is a second M¹_aM²_bM³_cO_x;

wherein

M¹ is selected from the group consisting of Ce, Co, Cu, Fe, Ga, Nb, Ni, Pr, Ru, Sn, Ti, Tm, W, Yb, Zn, and Zr;

M² and M³ are each independently selected from the group consisting of Al, Ba, Bi, Ca, Cd, Ce, Co, Cr, Cu, Fe, Ga, Ge, In, K, La, Mg, Mn, Mo, Na, Nb, Ni, Pb, Pr, Rb, Ru, Sb, Sc, Si, Sn, Sr, Ta, Ti, Tm, V, W, Y, Yb, Zn, and Zr, but M² and M³ are not the same in M¹_aM²_bM³_cO_x;

a, b and c are each independently about 0.0005 to about 1, provided that a+b+c=1; and

x is a number sufficient so that the oxygen present balances the charges of the other elements in the compound.

85. A method for analyzing at least one individual gas component in a multi-component gas mixture, comprising:

(a) providing an array of at least two chemo/electro-active materials, each chemo/electro-active material having a different electrical response characteristic upon exposure at a selected temperature to the individual gas component than each of the other chemo/electro-active materials, the electrical response characteristic of each material being quantifiable as a value, wherein the response value of at least one material is constant or varies by no more than about twenty percent during exposure of the material to an individual gas component at the selected temperature for a period of at least about one minute;

(b) heating the array to a temperature above 500°

C.;

(c) determining the electrical response value of each chemo/electro-active material upon exposure of the array to the gas mixture;

(d) inputting only the electrical responses of the chemo/electro-active materials to a pattern recognition technique; and

(e) performing an analysis of the individual gas component from the inputs in step (d).

86. A method according to claim 85 wherein at least one chemo/electro-active material, when at a temperature of about 400°

C. or more, (i) has an electrical resistivity in the range of about 1 ohm-cm to about 10⁵ ohm-cm, and (ii) exhibits a change in electrical resistance of at least about 0.1 percent upon exposure of the material to an analyte gas component, as compared to the resistance before exposure.

87. A method according to claim 85 wherein the electrical response is selected from the group consisting of resistance, impedance, capacitance, voltage or current.

88. A method according to claim 85 wherein the array is situated within the gas mixture, which has a temperature of about 400°

C. or more.

89. A method according to claim 85 wherein the array is situated in the gas mixture, which has a temperature of less than about 400°

C., and the array has a substantially constant temperature above 500°

C.

90. A method according to claim 85 wherein the component gases in the mixture are not separated.

91. A method according to claim 85 wherein the analysis performed comprises calculating the concentration within the gas mixture of the individual gas component.

92. A method according to claim 85 wherein the gas mixture comprises one or more members of the group consisting of oxygen, carbon monoxide, a nitrogen oxide, a hydrocarbon, CO₂, H₂S, sulfur dioxide, a halogen, hydrogen, water vapor, ammonia, alcohol, a solvent vapor, an ether, a ketone, an aldehyde, a carbonyl, and a microorganism.

93. A method according to claim 85 wherein the gas mixture comprises one or more members of the group consisting of oxygen, a nitrogen oxide, a hydrocarbon, and ammonia.

94. A method according to claim 85 in the gas mixture comprises one or more members of the group consisting of a nitrogen oxide and ammonia.

95. A method according to claim 85 wherein the gas mixture comprises one or more members of the group consisting of oxygen and a hydrocarbon.

96. A method according to claim 85 wherein the gas mixture is an emission from a combustion process.

97. A method according to claim 85 wherein the gas mixture is provided from a manufacturing process, a waste stream, environmental monitoring, or a medical, agricultural, food or beverage operation.

98. A method according to claim 85 wherein at least one chemo/electro-active material is a metal oxide.

99. A method according to claim 98 wherein the chemo/electro-active materials comprise one or more members of the group consisting of M¹O_x, M¹_aM²_bO_x, and M¹_aM²_bM³_cO_x wherein

M¹, M² and M³ are metals that form stable oxides when fired in the presence of oxygen above 500°

C.;

M¹ is selected from Periodic Groups 2-15 and the lanthanide group;

M² and M³ are independently selected from Periodic Groups 1-15 and the lanthanide group;

a, b, and c are each independently in the range of about 0.0005 to about 1, provided that a+b+c=1; and

x is a number sufficient so that the oxygen present balances the charges of the other elements in the compound.

100. A method according to claim 98 wherein the chemo/electro-active materials comprise one or more members of the group consisting of M¹O_x, M¹_aM²_bO_x, and M¹_aM²_bM³_cO_x wherein

M¹ is selected from the group consisting of Ce, Co, Cu, Fe, Ga, Nb, Ni, Pr, Ru, Sn, Ti, Tm, W, Yb, Zn, and Zr;

M² and M³ are each independently selected from the group consisting of Al, Ba, Bi, Ca, Cd, Ce, Co, Cr, Cu, Fe, Ga, Ge, In, K, La, Mg, Mn, Mo, Na, Nb, Ni, Pb, Pr, Rb, Ru, Sb, Sc, Si, Sn, Sr, Ta, Ti, Tm, V, W, Y, Yb, Zn, and Zr, but M² and M³ are not the same in M¹_aM²_bM³_cO_x;

a, b, and c are each independently in the range of about 0.0005 to about 1, provided that a+b+c=1; and

x is a number sufficient so that the oxygen present balances the charges of the other elements in the compound.

101. A method according to claim 98 wherein the chemo/electro-active materials comprise one or more members of the group consisting of M¹_Ox, M¹_aM²_bO_x, and M¹_aM²_bM³_cO_x wherein

M¹O_x is selected from the group consisting of Ce_aO_x, CoO_x, CuO_x, FeO_x, GaO_x, NbO_x, NiO_x, PrO_x, RuO_x, SnO_x, Ta_aO_x, TiO_x, TmO_x, WO_x, YbO_x, ZnO_x, ZrO_x, SnO_x with Ag additive, ZnO_x with Ag additive, TiO_x with Pt additive, ZnO_x with frit additive, NiO_x with frit additive, SnO_x with frit additive, or WO_x with frit additive;

M¹_aM²_bO_x is selected from the group consisting of Al_aCr_bO_x, Al_aFe_bO_x, Al_aMg_bO_x, Al_aNi_bO_x, Al_aTi_bO_x, Al_aV_bO_x, Ba_aCu_bO_x, Ba_aSn_bO_x, Ba_aZn_bO_x, Bi_aRu_bO_x, Bi_aSn_bO_x, Bi_aZn_bO_x, Ca_aSn_bO_x, Ca_aZn_bO_x, Cd_aSn_bO_x, Cd_aZn_bO_x, Ce_aFe_bO_x, Ce_aNb_bO_x, Ce_aTi_bO_x, Ce_aV_bO_x, Co_aCu_bO_x, Co_aGe_bO_x, Co_aLa_bO_x, Co_aMg_bO_x, Co_aNb_bO_x, Co_aPb_bO_x, Co_aSn_bO_x, Co_aV_bO_x, Co_aW_bO_x, Co_aZn_bO_x, Cr_aCu_bO_x, Cr_aLa_bO_x, Cr_aMn_bO_x, Cr_aNi_bO_x, Cr_aSi_bO_x, Cr_aTi_bO_x, Cr_aY_bO_x, Cr_aZn_bO_x, Cu_aFe_bO_x, Cu_aGa_bO_x, Cu_aLa_bO_x, Cu_aNa_bO_x, Cu_aNi_bO_x, Cu_aPb_bO_x, Cu_aSn_bO_x, Cu_aSr_bO_x, Cu_aTi_bO_x, Cu_aZn_bO_x, Cu_aZr_bO_x, Fe_aGa_bO_x, Fe_aLa_bO_x, Fe_aMo_bO_x, Fe_aNb_bO_x, Fe_aNi_bO_x, Fe_aSn_bO_x, Fe_aTi_bO_x, Fe_aW_bO_x, Fe_aZn_bO_x, Fe_aZr_bO_x, Ga_aLa_bO_x, Ga_aSn_bO_x, Ge_aNb_bO_x, Ge_aTi_bO_x, In_aSn_bO_x, K_aNb_bO_x, Mn_aNb_bO_x, Mn_aSn_bO_x, Mn_aTi_bO_x, Mn_aY_bO_x, Mn_aZn_bO_x, Mo_aPb_bO_x, Mo_aRb_bO_x, Mo_aSn_bO_x, Mo_aTi_bO_x, Mo_aZn_bO_x, Nb_aNi_bO_x, Nb_aNi_bO_x, Nb_aSr_bO_x, Nb_aTi_bO_x, Nb_aW_bO_x, Nb_aZr_bO_x, Ni_aSi_bO_x, Ni_aSn_bO_x, Ni_aY_bO_x, Ni_aZn_bO_x, Ni_aZr_bO_x, Pb_aSn_bO_x, Pb_aZn_bO_x, Rb_aW_bO_x, Ru_aSn_bO_x, Ru_aW_bO_x, Ru_aZn_bO_x, Sb_aSn_bO_x, Sb_aZn_bO_x, Sc_aZr_bO_x, Si_aSn_bO_x, Si_aTi_bO_x, Si_aW_bO_x, Si_aZn_bO_x, Sn_aTa_bO_x, Sn_aTi_bO_x, Sn_aW_bO_x, Sn_aZn_bO_x, Sn_aZr_bO_x, Sr_aTi_bO_x, Ta_aTi_bO_x, Ta_aZn_bO_x, Ta_aZr_bO_x, Ti_aV_bO_x, Ti_aW_bO_x, Ti_aZn_bO_x, Ti_aZr_bO_x, V_aZn_bO_x, V_aZn_bO_x, W_aZn_bO_x, W_aZr_bO_x, Y_aZr_bO_x, Zn_aZr_bO_x, Al_aNi_bO_x with frit additive, Cr_aTi_bO_x with frit additive, Fe_aNi_bO_x with frit additive, Fe_aTi_bO_x with frit additive, Nb_aTi_bO_x with frit additive, Nb_aW_bO_x with frit additive, Ni_aZn_bO_x with frit additive, Ni_aZr_bO_x with frit additive, or Ta_aTi_bO_x with frit additive; and

M¹_aM²_bM³_cO_x is selected from the group consisting of Al_aMg_bZn_cO_x, Al_aSi_bV_cO_x, Ba_aCu_bTi_cO_x, Ca_aCe_bZr_cO_x, Co_aNi_bTi_cO_x, Co_aNi_bZr_cO_x, Co_aPb_bSn_cO_x, Co_aPb_bZn_cO_x, Cr_aSr_bTi_cO_x, Cu_aFe_bMn_cO_x, Cu_aLa_bSr_cO_x, Fe_aNb_bTi_cO_x, Fe_aPb_bZn_cO_x, Fe_aSr_bTi_cO_x, Fe_aTa_bTi_cO_x, Fe_aW_bZr_cO_x, Ga_aTi_bZn_cO_x, La_aMn_bNa_cO_x, La_aMn_bSr_cO_x, Mn_aSr_aTi_cO_x, Mo_aPb_bZn_cO_x, Nb_aSr_bTi_cO_x, Nb_aSr_bW_cO_x, Nb_aTi_bZn_cO_x, Ni_aSr_bTi_cO_x, Sn_aW_bZn_cO_x, Sr_aTi_bV_cO_x, Sr_aTi_bZn_cO_x, or Ti_aW_bZr_cO_x;

a, b, and c are each independently in the range of about 0.0005 to about 1, provided that a+b+c=1; and

x is a number sufficient so that the oxygen present balances the charges of the other elements in the compound.

102. A method according to claim 98 wherein the chemo/electro-active materials comprise first and second chemo/electro-active materials selected from the pairings in the group consisting of

(i) the first material is M¹O_x, and the second material is M¹_aM²_bO_x;

(ii) the first material is M¹O_x, and the second material is M¹_aM²_bM³_cO_x;

(iii) the first material is M¹_aM²_bO_x, and the second material is M¹_aM²_bM³_cO_x;

(iv) the first material is a first M¹O_x, and the second material is a second M¹O_x,

(v) the first material is a first M¹_aM²_bO_x, and the second material is a second M¹_aM²_bO_x; and

(vi) the first material is a first M¹_aM²_bM³_cO_x, and the second material is a second M¹_aM²_bM³_cO_x;

wherein

M¹ is selected from the group consisting of Ce, Co, Cu, Fe, Ga, Nb, Ni, Pr, Ru, Sn, Ti, Tm, W, Yb, Zn, and Zr;

M² and M³ are each independently selected from the group consisting of Al, Ba, Bi, Ca, Cd, Ce, Co, Cr, Cu, Fe, Ga, Ge, In, K, La, Mg, Mn, Mo, Na, Nb, Ni, Pb, Pr, Rb, Ru, Sb, Sc, Si, Sn, Sr, Ta, Ti, Tm, V, W, Y, Yb, Zn, and Zr, but M² and M³ are not the same in M¹_aM²_bM³_cO_x,

a, b and c are each independently about 0.0005 to about 1, provided that a+b+c=1; and

x is a number sufficient so that the oxygen present balances the charges of the other elements in the compound.