Carbon nanotube sensor

• US 20070117213A1
• Filed: 05/16/2006
• Published: 05/24/2007
• Est. Priority Date: 03/18/2002
• Status: Active Grant

• Current Assignee: Alpine Electronics Incorporated (Alps Alpine Co., Ltd.)
• Original Assignee: Honeywell Incorporated (Honeywell International Inc.)
• Inventors: Cole, Barrett, Zook, J.
• Granted Patent: US 8,294,008 B2
• Time in Patent Office: Days
• US Class Current: 436/146
• CPC Class Codes: B82Y 15/00 Nanotechnology for interacting, sensing or actuating, e.g. quantum dots as markers in protein assays or molecular motors
• CPC Class Codes: B82Y 30/00 Nanotechnology for materials or surface science, e.g. nanocomposites
• CPC Class Codes: G01J 5/02 Constructional details
• CPC Class Codes: G01J 5/023 Particular leg structure or construction or shape; Nanotubes
• CPC Class Codes: G01J 5/024 Special manufacturing steps or sacrificial layers or layer structures
• CPC Class Codes: G01J 5/08 Optical arrangements
• CPC Class Codes: G01J 5/0853 having infrared absorbers other than the usual absorber layers deposited on infrared detectors like bolometers, wherein the heat propagation between the absorber and the detecting element occurs within a solid
• CPC Class Codes: G01N 33/0027 concerning the detector
• CPC Class Codes: Y10S 977/955 Of thermal property
• CPC Class Codes: Y10T 436/235 In an aqueous solution [e.g., TOC, etc.]

Abstract

Carbon nanotubes are formed on projections on a substrate. A metal, such as nickel is deposited on the substrate with optional platforms, and heated to form the projections. Carbon nanotubes are formed from the projections by heating in an ethylene, methane or CO atmosphere. A heat sensor is also formed proximate the carbon nanotubes. When exposed to IR radiation, the heat sensor detects changes in temperature representative of the IR radiation. In a gas sensor, a thermally isolated area, such as a pixel is formed on a substrate with an integrated heater. A pair of conductors each have a portion adjacent a portion of the other conductor with projections formed on the adjacent portions of the conductors. Multiple carbon nanotubes are formed between the conductors from one projection to another. IV characteristics of the nanotubes are measured between the conductors in the presence of a gas to be detected.

Claims

1. A method of sensing gas, the method comprising:

measuring electrical characteristics of carbon nanotubes formed between conductors on a thermally isolated surface in the presence of the gas; and

heating the thermally isolated surface using a heater integrated with the thermally isolated surface.

2. The method of claim 1 wherein the heater extends onto the thermally isolated surface.

3. The method of claim 2 wherein the heater comprises a platinum contact.

4. The method of claim 1 wherein the thermally isolated surface is heated to a temperature sufficient to drive off gas adsorbed by the carbon nanotubes.

5. The method of claim 4 wherein the temperature below the point at which carbon nanotubes are formed.

6. The method of claim 1 wherein the thermally isolated surface is heated to between approximately 300°

C. to 400°

C. to drive gas out of the carbon nanotubes.

7. The method of claim 1 wherein the electrical characteristics comprise IV characteristics of the carbon nanotubes.

8. The method of claim 7 wherein the IV characteristics differ between difference gases adsorbed by the carbon nanotubes.

9. The method of claim 1 wherein heating the thermally isolated surface is performed in the presence of the gas to be sensed.

10. A method of sensing gas, the method comprising:

absorbing gas in carbon nanotubes formed between conductors on a thermally isolated surface in the presence of the gas;

measuring electrical characteristics of the carbon nanotubes; and

heating the thermally isolated surface using a heater integrated with the thermally isolated surface to drive gas out of the carbon nanotubes.

11. The method of claim 10 wherein heating is done prior to absorbing the gas to drive off old gas from the carbon nanotubes.

12. The method of claim 11 wherein measuring is performed after gas has been absorbed by the carbon nanotubes.

13. The method of claim 10 wherein the thermally isolated surface is heated to a temperature sufficient to drive off gas adsorbed by the carbon nanotubes.

14. The method of claim 13 wherein the temperature below the point at which carbon nanotubes are formed.

15. The method of claim 10 wherein the thermally isolated surface is heated to between approximately 300°

C. to 400°

C. to drive gas out of the carbon nanotubes.

16. The method of claim 10 wherein the electrical characteristics comprise IV characteristics of the carbon nanotubes.

17. The method of claim 16 wherein the IV characteristics differ between difference gases adsorbed by the carbon nanotubes.

18. The method of claim 10 wherein heating the thermally isolated surface is performed in the presence of the gas to be sensed.

19. A method of sensing gas, the method comprising:

exposing the carbon nanotubes to a gas to be sensed;

heating the thermally isolated surface using a heater integrated with the thermally isolated surface to drive residual gas out of the carbon nanotubes;

after heating, absorbing gas in carbon nanotubes formed between conductors on a thermally isolated surface in the presence of the gas;

measuring IV characteristics of the carbon nanotubes to identify the absorbed gas; and

repeating heating, absorbing and measuring.

20. The method of claim 19 wherein the carbon nanotubes are exposed to the gas to be sensed after they are heated.