Sensor device and method for qualitative and quantitative analysis of gas phase substances

• US 20030039299A1
• Filed: 07/09/2002
• Published: 02/27/2003
• Est. Priority Date: 07/16/2001
• Status: Active Grant

• Current Assignee: Sensor Tech Inc.
• Original Assignee: Sensor Tech Inc.
• Inventors: Anderson, Karl F., Horovitz, Michael L.
• Granted Patent: US 7,329,389 B2
• Time in Patent Office: Days
• US Class Current: 374/141
• CPC Class Codes: G01N 27/123 for controlling the temperature temperature control per se G05D23/00
• CPC Class Codes: G01N 27/16 caused by burning or catalytic oxidation of surrounding material to be tested, e.g. of gas
• CPC Class Codes: G01N 27/3271 Amperometric enzyme electrodes for analytes in body fluids, e.g. glucose in blood amperometry per se G01N27/49; aspects concerning the enzyme reagent C12Q1/001
• CPC Class Codes: G01N 33/497 of gaseous biological material, e.g. breath
• CPC Class Codes: Y10T 29/49 Method of mechanical manufacture
• CPC Class Codes: Y10T 29/49002 Electrical device making
• CPC Class Codes: Y10T 436/11 Automated chemical analysis

Abstract

New sensors and methods for qualitative and quantitative analysis of multiple gaseous substances simultaneously with both high selectivity and high sensitivity are provided. The new sensors rely on a characteristic difference in energy between the interaction of a particular substance with a catalyst coated heat transfer device (HTD) and a non-catalyst coated (or one coated with a different catalyst) reference HTD. Molecular detection is achieved by an exothermic or endothermic chemical or physical reaction between the catalytic surface of the sensor and the molecule, tending to induce a temperature change of the sensor. Both high temperature and non-destructive low temperature detection are possible. The magnitude and rate of endothermic or exothermic heat transfer from a specific molecule-catalyst interaction is related to molecular concentration.

Claims

1. A sensor for detecting gas phase substances, comprising:

a) a sensing element, comprising

a first heater,

a first temperature detector in thermal contact with the first heater, and

a catalyst in thermal contact with the first temperature detector and the first heater;

b) a reference element, comprising

a second heater,

a second temperature detector in thermal contact with the second heater; and

c) a heat flow monitor for measuring the endothermic and exothermic heat flow to and from the sensing element relative to the reference element, resulting from thermal processes occurring at these elements.

2. The sensor of claim 1, wherein the sensing element further comprises a first heat conductor in thermal contact with the first variable resistance heater and wherein the reference element further comprises a second heat conductor in thermal contact with the second variable resistance heater.

3. The sensor of claim 1, wherein the first heater is a first variable resistance heater and wherein the second heater is a second variable resistance heater.

4. The sensor of claim 1, wherein the first temperature detector is a first resistance temperature detector and wherein the second temperature detector is a second resistance temperature detector.

5. The sensor of claim 4, wherein the heat flow monitor comprises an Anderson Loop measurement circuit topology for observing the difference in the electrical resistance between the first resistance temperature detector and the second resistance temperature detector.

6. The sensor of claim 4, wherein the heat flow monitor comprises a Wheatstone bridge measurement circuit topology for observing the difference in the electrical resistance between the first resistance temperature detector and the second resistance temperature detector.

7. The sensor of claim 1, further comprising a feedback control system to regulate the endothermic and exothermic heat flow to and from the sensing element to maintain the sensing element at the desired instantaneous temperature.

8. The sensor of claim 1, wherein the catalyst is selected from a metal oxide, boride, carbide, silicide, nitride, phosphide, arsenide, sulfide, selenide, telluride, fluoride, chloride, bromide, or iodide;

a non-metal oxide, boride, carbide, silicide, nitride, phosphide, arsenide, sulfide, selenide, telluride, fluoride, chloride, bromide, or iodide;

a metal;

an alloy;

a substance in which more than one metal or more than one non-metal are combined with an element;

a substance in which a metal or a non-metal are combined with more than one other element;

or a combination thereof.

9. The sensor of claim 1, wherein the catalyst comprises a metal, a metal oxide, or a combination thereof.

10. The sensor of claim 1, wherein the catalyst is selected from an oxide of scandium, titanium, zirconium, hafnium, niobium, tantalum, vanadium, nickel, manganese, iron, copper, chromium, cobalt, molybdenum, tungsten, osmium, rhenium, ruthenium, rhodium, palladium, silver, iridium, platinum, zinc, aluminum, tin, or a combination thereof.

11. The sensor of claim 1, wherein the heat flow monitor determines an amount of power required to hold the sensing element at a constant temperature as a result of an exothermic or endothermic interaction between the catalyst and the gas phase substance.

12. The sensor of claim 1, wherein the heat flow monitor determines an amount of power required to hold the sensing element at a constant temperature as a result of an exothermic or endothermic interaction between the catalyst and the gas phase substance, as compared to the amount of power required to hold the reference element at a constant temperature.

13. The sensor of claim 1, wherein the heat flow monitor determines a temperature change of the sensing element as a result of an exothermic or endothermic interaction between the catalyst and the gas phase substance.

14. The sensor of claim 1, wherein the heat flow monitor determines a temperature change of the sensing element as a result of an exothermic or endothermic interaction between the catalyst and the gas phase substance, as compared to the temperature of the reference element.

15. The sensor of claim 1, wherein the thermal processes are selected from an oxidation, a reduction, an acid-base reaction, an adsorption, a desorption, a hydrogen-bonding process, a van der Waals interaction, an electrostatic interaction, a bond-making reaction, a bond-breaking reaction, or a combination thereof.

16. A sensor for detecting gas phase substances, comprising:

a) a sensing element, comprising

a first resistance temperature detector which functions as a temperature detector and a variable resistance heater, and

a catalyst in thermal contact with the first resistance temperature detector;

b) a reference element, comprising

a second resistance temperature detector which functions as a temperature detector and a variable resistance heater; and

c) a heat flow monitor for measuring the endothermic and exothermic heat flow to and from the sensing element relative to the reference element, resulting from thermal processes occurring at these elements.

17. The sensor of claim 16, wherein the first and second resistance temperature detectors comprise a material selected from nickel, platinum, or tungsten.

18. A sensor for detecting gas phase substances, comprising:

a) a sensing element, comprising

a first resistance temperature detector which functions as a temperature detector and a variable resistance heater, and

a metal oxide catalyst in thermal contact with the first resistance temperature detector;

b) a reference element, comprising

a second resistance temperature detector which functions as a temperature detector and a variable resistance heater;

c) a heat flow monitor for measuring the endothermic and exothermic heat flow to and from the sensing element relative to the reference element resulting from thermal processes occurring at these elements, comprising an Anderson Loop measurement circuit topology for observing the difference in the electrical resistance between the first resistance temperature detector and the second resistance temperature detector; and

d) a feedback control system to regulate the heat flow to and from the sensing element, to maintain the sensing element at the desired instantaneous temperature.

19. A sensor for detecting gas phase substances, comprising:

a) a sensing element, comprising

a heater,

a temperature detector in thermal contact with the heater, and

a catalyst in thermal contact with the temperature detector and the heater;

b) a heat flow monitor for measuring the endothermic and exothermic heat flow to and from the sensing element relative to the environment, resulting from thermal processes occurring at the sensing element.

20. The sensor of claim 19, wherein the sensing element further comprises a heat conductor in thermal contact with the variable resistance heater.

21. The sensor of claim 19, wherein the heater is a variable resistance heater.

22. The sensor of claim 19, wherein the temperature detector is a resistance temperature detector.

23. The sensor of claim 19, further comprising a feedback control system to regulate the endothermic and exothermic heat flow to and from the sensing element to maintain the sensing element at the desired instantaneous temperature.

24. The sensor of claim 19, wherein the catalyst is selected from a metal oxide, boride, carbide, silicide, nitride, phosphide, arsenide, sulfide, selenide, telluride, fluoride, chloride, bromide, or iodide;

a non-metal oxide, boride, carbide, silicide, nitride, phosphide, arsenide, sulfide, selenide, telluride, fluoride, chloride, bromide, or iodide;

a metal;

an alloy;

a substance in which more than one metal or more than one non-metal are combined with an element;

a substance in which a metal or a non-metal are combined with more than one other element;

or a combination thereof.

25. The sensor of claim 19, wherein the catalyst comprises a metal, a metal oxide, or a combination thereof.

26. The sensor of claim 19, wherein the catalyst is selected from an oxide of scandium, titanium, zirconium, hafnium, niobium, tantalum, vanadium, nickel, manganese, iron, copper, chromium, cobalt, molybdenum, tungsten, osmium, rhenium, ruthenium, rhodium, palladium, silver, iridium, platinum, zinc, aluminum, tin, or a combination thereof.

27. The sensor of claim 19, wherein the heat flow monitor determines an amount of power required to hold the sensing element at a constant temperature as a result of an exothermic or endothermic interaction between the catalyst and the gas phase substance.

28. The sensor of claim 19, wherein the heat flow monitor determines a temperature change of the sensing element as a result of an exothermic or endothermic interaction between the catalyst and the gas phase substance.

29. The sensor of claim 19, wherein the thermal processes are selected from an oxidation, a reduction, an acid-base reaction, an adsorption, a desorption, a hydrogen-bonding process, a van der Waals interaction, an electrostatic interaction, a bond-making reaction, a bond-breaking reaction, or a combination thereof.

30. A sensor for detecting gas phase substances, comprising:

a) a sensing element, comprising

a resistance temperature detector which functions as a temperature detector and a variable resistance heater, and

a catalyst in thermal contact with the resistance temperature detector; and

b) a heat flow monitor for measuring the endothermic and exothermic heat flow to and from the sensing element relative to the environment, resulting from thermal processes occurring at the sensing element.

31. The sensor of claim 30, wherein the resistance temperature detector comprises a material selected from nickel, platinum, or tungsten.

32. A sensor for detecting gas phase substances, comprising:

a) a first sensing element, comprising

a first variable resistance heater,

a first temperature detector in thermal contact with the first variable resistance heater, and

a first catalyst in thermal contact with the first temperature detector and the first variable resistance heater;

b) a second sensing element, comprising

a second variable resistance heater,

a second temperature detector in thermal contact with the second variable resistance heater, and

a second catalyst in thermal contact with the second temperature detector and the second variable resistance heater; and

c) a heat flow monitor for measuring the endothermic and exothermic heat flow to and from the first sensing element relative to the second sensing element, resulting from thermal processes occurring at these elements.

33. A method of detecting a gas phase substance at a predetermined temperature, comprising:

a) contacting the substance with a sensing element and a reference element, wherein the sensing element comprises

a first heater,

a first temperature detector in thermal contact with the first heater, and

a catalyst in thermal contact with the first temperature detector and the first heater;

and wherein the reference element comprises

a second heater,

a second temperature detector in thermal contact with the second heater, and

b) regulating the temperature of the sensing element and the reference element to substantially match the specific temperature at which reaction occurs between the catalyst and the substance; and

c) measuring the heat flow to and from the sensing element relative to the reference element, resulting from exothermic and endothermic processes occurring at these elements.

34. The method of claim 33, wherein the sensing element further comprises a first heat conductor in thermal contact with the first variable resistance heater and wherein the reference element further comprises a second heat conductor in thermal contact with the second variable resistance heater.

35. The method of claim 33, wherein the first heater is a first variable resistance heater and wherein the second heater is a second variable resistance heater.

36. The method of claim 33, wherein the first temperature detector is a first resistance temperature detector and wherein the second temperature detector is a second resistance temperature detector.

37. The method of claim 33, wherein the catalyst is selected from a metal oxide, boride, carbide, suicide, nitride, phosphide, arsenide, sulfide, selenide, telluride, fluoride, chloride, bromide, or iodide;

a non-metal oxide, boride, carbide, silicide, nitride, phosphide, arsenide, sulfide, selenide, telluride, fluoride, chloride, bromide, or iodide;

a metal;

an alloy;

a substance in which more than one metal or more than one non-metal are combined with an element;

a substance in which a metal or a non-metal are combined with more than one other element;

or a combination thereof.

38. The method of claim 33, wherein the exothermic and endothermic processes are selected from an oxidation, a reduction, an acid-base reaction, an adsorption, a desorption, a hydrogen-bonding process, a van der Waals interaction, an electrostatic interaction, a bond-making reaction, a bond-breaking reaction, or a combination thereof.

39. The method of claim 33, further comprising employing a feedback control system to regulate the heat flow to and from the sensing element to maintain the desired instantaneous sensing element temperature.

40. The method of claim 33, wherein the temperature of the sensing element and the reference element are regulated between about −

196°

C. and about 260°

C.

41. The method of claim 33, wherein the temperature of the sensing element and the reference element are regulated between about −

78°

C. and about 232°

C.

42. The method of claim 33, wherein the temperature of the sensing element and the reference element are regulated between about 0°

C. and about 232°

C.

43. The method of claim 33, wherein the temperature of the sensing element and the reference element are regulated between about 25°

C. and about 200°

C.

44. The method of claim 33, wherein measuring the heat flow to and from the sensing element determines either the temperature of the sensing element or the non-catalytic power to the sensing element.

45. The method of claim 33, wherein measuring the heat flow to and from the sensing element determines either the temperature difference or the non-catalytic power difference between the sensing element and the reference element.

46. A method of detecting a gas phase substance at a predetermined temperature, comprising:

a) contacting the substance with a sensing element and a reference element, wherein the sensing element comprises

a first resistance temperature detector which functions as a temperature detector and a variable resistance heater, and

a catalyst in thermal contact with the first resistance temperature detector;

and wherein the reference element comprises

a second resistance temperature detector which functions as a temperature detector and a variable resistance heater;

b) regulating the temperature of the sensing element and the reference element to substantially match the specific temperature at which reaction occurs between the catalyst and the substance; and

c) measuring the heat flow to and from the sensing element relative to the reference element, resulting from exothermic and endothermic processes occurring at these elements.

47. The method of claim 46, wherein the first and second resistance temperature detectors comprise a material selected from nickel, platinum, or tungsten.

48. A method of detecting a gas phase substance at a predetermined temperature, comprising:

a) contacting the substance with a sensing element, wherein the sensing element comprises

a first variable resistance heater,

a first temperature detector in thermal contact with the first variable resistance heater, and

a catalyst in thermal contact with the first temperature detector and the first variable resistance heater;

b) regulating the temperature of the sensing element to substantially match the specific temperature at which reaction occurs between the catalyst and the substance;

c) measuring the heat flow to and from the sensing element resulting from exothermic and endothermic processes occurring at the sensing element;

d) contacting the substance with a reference element, wherein the reference element comprises

a second variable resistance heater, and

a second temperature detector in thermal contact with second the variable resistance heater;

e) regulating the temperature of the reference element to substantially match the temperature of the sensor element;

f) measuring the heat flow to and from the reference element resulting from exothermic and endothermic processes occurring at the reference element;

g) comparing the heat flow to and from the sensing element with the heat flow heat flow to and from the reference element to detect the substance.

49. A method of detecting multiple gas phase substances by calorimetric spectroscopy, comprising:

a) contacting the substance with at least one sensing element and at least one reference element, wherein the sensing element comprises

a first variable resistance heater,

a first temperature detector in thermal contact with the first variable resistance heater, and

a catalyst in thermal contact with the first temperature detector and the first variable resistance heater;

and wherein the reference element comprises

a second variable resistance heater,

a second temperature detector in thermal contact with the second variable resistance heater;

b) increasing or decreasing the temperature of the sensing element and the reference element concurrently over a temperature range, such that the discrete temperature at which reaction occurs between the catalyst and a substance is momentarily achieved;

c) measuring the heat flow to or from the sensing element relative to the reference element, resulting from exothermic and endothermic processes occurring at these elements, over the same temperature range.

50. The method of claim 49, further comprising employing a feedback control system to regulate the heat flow to and from the sensing element to maintain the desired instantaneous sensing element temperature.

51. The method of claim 49, wherein the temperature of the sensing element and the reference element are regulated over a range of between about −

196°

C. to about 260°

C.

52. The method of claim 49, wherein the exothermic and endothermic processes are selected from an oxidation, a reduction, an acid-base reaction, an adsorption, a desorption, a hydrogen-bonding process, a van der Waals interaction, an electrostatic interaction, a bond-making reaction, a bond-breaking reaction, or a combination thereof.