CARBON NANOTUBE SENSING SYSTEM, CARBON NANOTUBE DEW POINT HYGROMETER, METHOD OF USE THEREOF AND METHOD OF FORMING A CARBON NANOTUBE DEW POINT HYGROMETER

• US 20150233856A1
• Filed: 02/26/2015
• Published: 08/20/2015
• Est. Priority Date: 09/05/2008
• Status: Active Grant

• Current Assignee: Cosa Xentaur, The Research Foundation for The State University of New York (State University of New York)
• Original Assignee: Cosa Xentaur, The Research Foundation for The State University of New York (State University of New York)
• Inventors: Samuilov, Vladimir, Ayres, John Lewis
• Granted Patent: US 10,101,219 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: G01K 13/00 Thermometers specially adapted for specific purposes
• CPC Class Codes: G01N 27/121 for determining moisture content, e.g. humidity, of the fluid moisture content of the tested material G01N27/048
• CPC Class Codes: G01N 27/127 comprising nanoparticles

Abstract

A system, a method of use, and a Carbon Nanotube (CNT) condensation sensor for determining a dew point and/or ice point is provided. For example, a sensing system may include a thermal device configured to generate heating or cooling to change a temperature of a surface, a temperature sensor for measuring the temperature of the surface, a controller configured to control the thermal device, a carbon nanotube (CNT) condensation sensor mounted on the surface having a moisture sensitive resistance and a processor configured to determine one or more parameters based on the moisture sensitive resistance of the CNT condensation sensor and the temperature measured by the temperature sensor. The one or more parameter can be used to determine the dew point and/or ice point. A method for forming a carbon nanotube (CNT) condensation sensor is also provided.

Claims

1. A system comprising:

a thermal device configured to generate heating or cooling to change a temperature of a surface;

a temperature sensor for measuring a temperature of the surface;

a controller configured to control the thermal device;

a carbon nanotube (CNT) condensation sensor mounted on the surface having a moisture sensitive resistance;

a processor configured to determine one or more parameters based on the moisture sensitive resistance of the CNT condensation sensor and the temperature measured by the temperature sensor.

2. The system of claim 1, wherein the controller is configure to control a temperature scan rate of the thermal device.

3. The system of claim 2, wherein the temperature scan rate is between about 0.001°

C./sec and about 10°

C./sec.

4. The system of claim 2, wherein the temperature scan rate includes a fast temperature scan rate of between about 0.1 and about 10°

C./sec.

5. The system of claim 4, wherein the temperature scan rate includes a slow temperature scan rate of between about 0.001 and about 0.1°

C./sec.

6. The system of claim 5, wherein the controller is configured to switch between the fast temperature scan rate and the temperature slow scan rate.

7. The system of claim 1, wherein the thermal device is a multi-stage thermoelectric device.

8. The system of claim 1, further comprising a current source coupled to the temperature sensor and to the CNT condensation sensor;

and voltage detector configured to detect voltage across the temperature sensor and the CNT condensation sensor, the detected voltages being proportional to a resistance of the temperature sensor and the moisture sensitive resistance of the CNT condensation sensor.

9. The system of claim 1, wherein the processor is configured to determine the one or more parameters based on analyzing the moisture sensitive resistance over time.

10. The system of claim 9, wherein the one or more parameters being selected from a group consisting of maximum resistance point with respect to temperature, a first derivative of resistance with respect to temperature and a second derivative of resistance with respect to temperature.

11. The system of claim 10, wherein the processor is configured to determine a dew point based on at least one of the one or more parameters.

12. The system of claim 11, wherein when the dew point is greater than 0(°

C.), a T_inflection (°

C.) is the dew point, where T_inflection is a temperature where;

     1) the first derivative is a minimum,

     2) the first derivative is less than 0 for both T>

T_inflection and T<

T_inflection,

     3) the second derivative equals 0 and

     4) the second derivative is greater than 0 for surface temperatures T_surface (°

C.) above T_inflection (°

C.) and the second derivative is less than 0 for surface temperatures T_surface (°

C.) below T_inflection (°

C.).

13. The system of claim 11, wherein when the dew point is less than 0(°

C.), the dew point is determined based on a frost point, T_frost, when no T_inflection is detected, where T_frost=T_ice, where T_ice a temperature where;

     1) the first derivative is less than 0 for T_surface (°

C.)>

T_ice (°

C.),

     2) the first derivative is greater than 0 for T (°

C.)<

T_ice (°

C.),

     3) the first derivative is equal to 0 at T_ice (°

C.) or T) or the first derivative is undefined at T_ice (°

C.),

     4) conditions 1-3 resulting in a maximum extremum or “

peak”

in the R_cnt (ohms) versus T_surface (°

C.) curve where T_surface (°

C.) equals T_ice (°

C.), and

     5) immediately following T_ice (°

C.), as the surface temperature is further decreased, a magnitude of the moisture sensitive resistance R_CNT drops off abruptly in magnitude providing a characteristic icing signature.

14. A method comprising:

controlling a temperature of a surface, where a carbon nanotube (CNT) condensation sensor is mounted to the surface, the temperature of the surface is controlled to start at a maximum temperature, controlling the temperature including decreasing the temperature of the surface at a controllable scan rate;

detecting, continuously a voltage across the CNT condensation sensor over time;

detecting, continuously a voltage across a temperature sensor over time, the temperature sensor being configured to sense a temperature of the surface;

calculating moisture sensitive resistance of the CNT condensation sensor from the continuously detected voltage across the CNT condensation sensor; and

determining one or more parameters based on the moisture sensitive resistance and the temperature.

15. The method of claim 14, wherein the one or more parameters being selected from a group consisting of maximum resistance point with respect to temperature, a first derivative of resistance with respect to temperature and a second derivative of resistance with respect to temperature.

16. The method of claim 15, further comprising:

determining an ice point temperature T_ice based the one or more parameters.

17. The method of claim 15, wherein the decrease in the temperature of the surface is stopped at the T_ice.

18. The method of claim 16, wherein the T_ice is where:

1) the first derivative is less than 0 for T_surface (°

C.)>

T_ice (°

C.),

     2) the first derivative is greater than 0 for T (°

C.)<

T_ice (°

C.),

     3) the first derivative is equal to 0 at T_ice(°

C.) or the first derivative is undefined at T_ice(°

C.),

     4) conditions 1-3 resulting in a maximum extremum or “

peak”

in the R_cnt (ohms) versus T_surface (°

C.) curve where T_surface (°

C.) equals T_ice(°

C.), and

     5) immediately following T_ice(°

C.), as the surface temperature is further decreased, a magnitude of the moisture sensitive resistance R_CNT drops off abruptly in magnitude providing a characteristic icing signature.

19. The method of claim 16, further comprising:

detecting an inflection point temperature based the one or more parameters.

20. The method of claim 19, wherein T_inflection is a temperature where:

1) the first derivative is a minimum,

     2) the first derivative is less than 0 for both T>

T_inflection and T<

T_inflection,

     3) the second derivative equals 0 and

     4) the second derivative is greater than 0 for surface temperatures T_surface (°

C.) above T_inflection (°

C.) and the second derivative is less than 0 for surface temperatures T_surface (°

C.) below T_inflection (°

C.).

21. The method of claim 20, further comprising:

determining a dew point temperature T_dew.

22. The method of claim 21, wherein when T_inflection is greater than 0, T_dew=T_inflection.

23. The method of claim 21, wherein when T_inflection is less than 0, T_dew is determined based on a frost point T_frost.

24. The method of claim 20, wherein the method detects the T_dew of polar molecules in a gas mixture.

25. The method of claim 24, wherein the gas mixture includes components selected from a group consisting of oxygen (O₂), nitrogen (N₂), hydrogen (H₂), carbon dioxide (CO₂), and hydrocarbon molecules such as methane (CH₄), ethane (C₂H₆), propane (C₃H₈), and butane (C₄H₁₀).

26. The method of claim 24, wherein the polar molecules are selected from a group consisting of water and ammonia.

27. The method of claim 20, wherein the method detects the T_dew of a target polar molecule in a background gas stream consisting of nonpolar molecules and polar molecules in which the dew point of the background polar molecules is lower than the dew point of the target polar molecule.

28. The method of claim 17, wherein the controlling of the temperature of a surface, further including increasing the temperature of the surface to the maximum temperature when the T_ice is reached.

29. A method for making a carbon nanotube (CNT) condensation sensor comprising:

placing at least one carbon nanotube in an acid solution generating a dispersion;

applying mechanical energy to the dispersion with the at least one carbon nanotube for a first predetermined time;

heating the dispersion with the at least one carbon nanotube to a first predetermined temperature for a second predetermined time;

applying mechanical energy to the dispersion with the at least one carbon nanotube while heating;

cooling the dispersion with the at least one carbon nanotube to a second predetermined temperature, after heating, for a third predetermined time;

applying mechanical energy to the dispersion with the at least one carbon nanotube while cooling;

filtering the dispersion with the at least one carbon nanotube using deionized water;

heating the filtered dispersion with the at least one carbon nanotube to a third determined temperature for a fourth predetermined time to generate a carbon nanotube powder;

placing the carbon nanotube powder in deionized water;

depositing the carbon nanotube powder in deionized water on a surface as a carbon nanotube film; and

placing the carbon nanotube film on an insulating dielectric surface, the insulating dielectric surface having a pattern of conducted material deposited on a portion of the insulating dielectric surface as an electric contact, the pattern of conductive material making contact with the carbon nanotube film.

30. The method for making a carbon nanotube (CNT) condensation sensor according to claim 29, wherein the first predetermined time is about 1 hour to about 24 hours and the applied mechanical energy is sonication.

31. The method for making a carbon nanotube (CNT) condensation sensor according to claim 29, wherein the first predetermined temperature is about 45°

C. to about 70°

C.

32. The method for making a carbon nanotube (CNT) condensation sensor according to claim 31, wherein the second predetermined time is about 1 hour to about 24 hours.

33. The method for making a carbon nanotube (CNT) condensation sensor according to claim 31, wherein the applying mechanical energy while heating is stirring.

34. The method for making a carbon nanotube (CNT) condensation sensor according to claim 29, wherein the second predetermined temperature is about 20°

C. to about 40°

C.

35. The method for making a carbon nanotube (CNT) condensation sensor according to claim 34, wherein the third predetermined time is about 1 day to about 5 days.

36. The method for making a carbon nanotube (CNT) condensation sensor according to claim 35, wherein the applying mechanical energy while cooling is stirring.

37. The method for making a carbon nanotube (CNT) condensation sensor according to claim 29, wherein the third predetermined temperature is about 70°

C. to about 120°

C.

38. The method for making a carbon nanotube (CNT) condensation sensor according to claim 29, wherein the fourth predetermined time is about 1 hour to about 24 hours.

39. The method for making a carbon nanotube (CNT) condensation sensor according to claim 29, wherein the insulating dielectric surface is selected from a group consisting of aluminum oxide and silicon dioxide.

40. The method for making a carbon nanotube (CNT) condensation sensor according to claim 29, wherein the depositing is by filtration onto the surface, and wherein the surface is removable or dissolvable.

41. The method for making a carbon nanotube (CNT) condensation sensor according to claim 29, wherein the acid solution comprises concentrated sulfuric acid and concentrated nitric acid.