Carbon nanotube flow sensor device and method

• US 6,718,834 B1
• Filed: 11/29/2002
• Issued: 04/13/2004
• Est. Priority Date: 11/29/2002
• Status: Expired due to Fees

• Current Assignee: Indian Institute of Science
• Original Assignee: Indian Institute of Science
• Inventors: Sood, Ajay Kumar, Ghosh, Shankar
• Primary Examiner(s): Lefkowitz, Edward
• Assistant Examiner(s): THOMPSON, JEWEL VERGIE
• Application Number:
  US10/306,838
• Time in Patent Office: 501 Days
• Field of Search: 738/610.8, 73/190.5, 166/336, 166/113, 423/445, 429/34, 429/37, 429/219, 428/408, 310/300, 385/22, 29/253.5
• US Class Current: 73/861.08
• CPC Class Codes: G01F 1/56 by using electric or magnetic effects G01F1/66 takes precedence
• CPC Class Codes: G01F 1/64 by measuring electrical currents passing through the fluid flow; measuring electrical potential generated by the fluid flow, e.g. by electrochemical, contact or friction effects G01F1/58 takes precedence
• CPC Class Codes: G01P 5/08 by measuring variation of an electric variable directly affected by the flow, e.g. by using dynamo-electric effect
• CPC Class Codes: Y10S 977/742 Carbon nanotubes, CNTs
• CPC Class Codes: Y10S 977/953 Detector using nanostructure

Abstract

A method and device for measuring the flow of a liquid utilizes at least one carbon nanotube. More particularly, the velocity of a liquid along the direction of the flow is measured as a function of the current/voltage generated in at least one carbon nanotube due to the flow of the liquid along its surface.

Claims

1. A flow sensing device useful for measurement of liquid flow velocities along the direction of the liquid flow and irrespective of a nature of the liquid, said device comprising at least one carbon nanotube, said at least one carbon nanotube being arranged between at least two conducting elements, the two conducting elements connecting the at least one carbon nanotube to an electricity measurement device for measuring electricity generated as a function of a rate of flow of the liquid.

2. A device as claimed in claim 1 wherein the carbon nanotube is a single wall type carbon nanotube.

3. A device as claimed in claim 1 wherein the carbon nanotube is of a multiwall type carbon nanotube.

4. A device as claimed in claim 1 wherein the electricity measurement device comprises an ammeter to measure a current generated across opposite ends of said at least one carbon nanotube or a voltmeter to measure a potential difference across the opposite ends of the at least one carbon nanotube.

5. A device as claimed in claim 1 wherein the flow sensing device further comprises of a plurality of carbon nanotubes all connected in series or parallel with a single one of the two conducting elements each being provided at the respective extreme ends of the plurality of carbon nanotubes.

6. A device as claimed in claim 5 wherein the plurality of carbon nanotubes are connected in series so as to measure a potential difference generated across the ends of the plurality of carbon nanotubes.

7. A device as claimed in claim 5 wherein the plurality of nanotubes are connected in parallel to each other so as to enable determination of a current generated across two ohmic contacts formed by the respective conducting elements at the ends thereof.

8. A device as claimed in claim 1 wherein the flow sensing device further comprises a protective insulating coating to prevent electrical contact with the liquid.

9. A device as claimed in claim 1 wherein the flow sensing device is provided on a insulated base.

10. A device as claimed in claim 1 wherein the conducting elements each comprises of a wire.

11. A device as claimed in claim 1 wherein the conducting elements each comprises of an electrode.

12. A device as claimed in claim 1 wherein the conducting elements each comprises of a combination of wire connected to an electrode.

13. A device as claimed in claim 1 wherein the liquid whose flow velocity is determined is flowing water.

14. A device as claimed in claim 1 wherein the liquid is a biological fluid.

15. A device as claimed in claim 1 wherein the biological fluid is blood.

16. A device as in claim 1 wherein the at least one carbon nanotube is immersed in the liquid at rest and generates a rest voltage in the nanotube, a velocity of the liquid being calculated as a function of a voltage generated in the carbon nanotube during flow after deduction of the rest voltage.

17. A device as in claim 1 wherein a response time of the flow sensing device is less than 0.01 seconds.

18. A device as in claim 1 wherein the flow sensing device generates the electricity without an external power source.

19. A device as in claim 1 wherein the flow sensing device measures a flow velocity of the liquid having a velocity on the order of 10⁻

8 to 10<sup>−

5</sup> cm/sec.

20. A method for determination of liquid flow velocities irrespective of the nature of the liquid the method comprising:

immersing in said liquid a flow sensing device comprising of at least one carbon nanotube arranged between two conducting elements which connect the at least one carbon nanotube to an electricity measurement device, the liquid flow over the at least one carbon nanotube generating a flow of electricity along the direction of the liquid flow by forcing free charges present in the at least one nanotube, the electrical energy generated by movement of the free charges in the nanotube being transmitted by said the conducting elements to the electricity measurement device provided external to the liquid flow, to measure electricity generated as a function of a rate of flow of the liquid.

21. A method as claimed in claim 20 wherein the liquid comprises a polar liquid.

22. A method as claimed in claim 21 wherein the polar liquid is selected from water and a biological fluid.

23. A method as claimed in claim 22 wherein the biological fluid is blood.

24. A method as claimed in claim 20 wherein the liquid comprises a non-polar liquid selected from methanol, ethanol, and any other non-polar liquid.

25. A method as claimed in claim 20 wherein the carbon nanotube is a single wall type carbon nanotube.

26. A method as claimed in claim 20 wherein the carbon nanotube is of a multiwall type carbon nanotube.

27. A method as in claim 20 wherein the electricity is generated without an external power source.

28. A method as in claim 20 wherein the flow sensing device measures a flow velocity of the liquid having a velocity on the order of 10⁻

8 to 10<sup>−

5</sup> cm/sec.

29. A method for determination of liquid flow velocities irrespective of a nature of a liquid or the flow velocity thereof, which comprises measuring in said liquid a flow sensing device comprising of at least one carbon nanotube connected at each end through at least a conducting element to a electricity measurement means, the liquid flow over said at least one carbon nanotube generating a flow of electricity along the direction of the liquid flow by forcing free charges present in the at least one nanotube, said electrical energy being transmitted by said conducting element to said electricity measurement means provided external to the liquid flow, to measure the electricity generated as a function of a rate of flow of said liquid;

wherein the forcing of the free charges is along the direction of the liquid flow due to the Coulombic interaction between the Coulombic field of the liquid and the free charges, thereby ensuring that only velocity along the direction of the liquid flow is determined.

30. A method for determination of liquid flow velocities irrespective of a nature of the liquid or a flow velocity thereof, which comprises measuring in said liquid a flow sensing device comprising of at least one carbon nanotube connected at each end through at least a conducting element to a electricity measurement means, the liquid flow over said at least one carbon nanotube generating a flow of electricity along the direction of the liquid flow by forcing free charges present in the at least one nanotube, said electrical energy being transmitted by said conducting element to said electricity measurement means provided external to the liquid flow, to measure the electricity generated as a function of a rate of flow of said liquid

wherein the at least one carbon nanotube is immersed in the liquid at rest and generates a rest voltage in the nanotube, an exact velocity of the liquid flow being calculated as a function of a voltage generated in the carbon nanotube during flow after deduction of the rest voltage.

31. A method for determination of liquid flow velocities irrespective of a nature of the liquid or a flow velocity thereof, which comprises measuring in said liquid a flow sensing device comprising of at least one carbon nanotube connected at each end through at least a conducting element to a electricity measurement means, the liquid flow over said at least one carbon nanotube generating a flow of electricity along the direction of the liquid flow by forcing free charges present in the at least one nanotube, said electrical energy being transmitted by said conducting element to said electricity measurement means provided external to the liquid flow, to measure the electricity generated as a function of a rate of flow of said liquid

wherein a response time of the flow sensing device is less than 0.01 seconds.

32. An energy conversion device comprising a energy generation device comprising one or more carbon nanotubes, each of the one or more nanotubes comprising of at least one carbon nanotube arranged between two conducting elements connecting the at least one carbon nanotube to an electricity storage or usage device to store or use electricity generated in the at least one carbon nanotubes due to the liquid flow along the surface thereof.

33. An energy conversion device as claimed in claim 32 wherein the carbon nanotube is a single wall type carbon nanotube.

34. An energy conversion device as claimed in claim 32 wherein the carbon nanotube is of a multiwall type carbon nanotube.

35. An energy conversion device as claimed in claim 32 wherein the energy generation device comprises a plurality of carbon nanotubes.

36. An energy conversion device as claimed in claim 35 wherein the plurality of carbon nanotubes are connected in series.

37. An energy conversion device as claimed in claim 35 wherein the plurality of nanotubes are connected in parallel.

38. An energy conversion device as claimed in claim 32 wherein the energy conversion device further comprises a protective insulating coating to prevent electrical contact with the liquid, thereby ensuring that accidental discharge of electricity generated due to liquid flow along the surface thereof to the liquid does not occur.

39. An energy conversion device as claimed in claim 32 wherein the energy conversion device is provided on an insulated base.

40. An energy conversion device as claimed in claim 33 wherein the energy storage device comprises of a battery or storage cell.

41. An energy conversion device as claimed in claim 32 wherein the conducting elements each comprises of a wire.

42. An energy conversion device as claimed in claim 32 wherein the conducting elements each comprises of an electrode.

43. An energy conversion device as claimed in claim 32 wherein the conducting elements each comprises of a combination of a wire connected to an electrode.

44. An energy conversion device as claimed in claim 32 wherein the liquid whose flow velocity is determined is flowing water.

45. An energy conversion device as claimed in claim 32 wherein the liquid is a biological fluid.

46. An energy conversion device as claimed in claim 45 wherein the biological fluid is blood.

47. A method for the generating electrical energy using an energy conversion device comprising an energy generation device comprising one or more carbon nanotubes, each of said one or more nanotube comprising of at least one carbon nanotube arranged between two conducting elements connecting the at least one carbon nanotube to an electricity storage or usage device, the flow of the liquid along the surface of the energy conversion device forcing the free charges in the one or more carbon nanotubes to flow along the direction of the liquid flow, thereby generating electrical energy, said electrical energy being transmitted to the energy storage or usage device through the two conducting elements.

48. A method as claimed in claim 47 wherein the carbon nanotube is a single wall type carbon nanotube.

49. A method as claimed in claim 47 wherein the carbon nanotube is of a multiwall type carbon nanotube.

50. A method as claimed in claim 47 wherein the energy generation device comprises a plurality of carbon nanotubes.

51. A method as claimed in claim 50 wherein the plurality of carbon nanotubes are connected in series.

52. A method as claimed in claim 50 wherein the plurality of nanotubes are connected in parallel.

53. A method as claimed in claim 47 wherein the energy conversion device further comprises a protective insulating coating to prevent electrical contact with the liquid, thereby ensuring that accidental discharge of electricity generated due to liquid flow along the surface thereof to the liquid does not occur.

54. A method as claimed in claim 47 wherein the energy conversion device is provided on an insulated base.

55. A method as claimed in claim 47 wherein the energy storage device comprises a battery or storage cell.

56. A method as claimed in claim 47 wherein the energy conversion device functions as a battery of a cardiac pacemaker device.

57. A flow sensing device for measuring liquid flow velocities, the device comprising:

two electrodes;

at least one carbon nanotube sandwiched between the two electrodes; and

an electricity measurement device for measuring electricity generated by the flow sensing device as a function of a rate of flow of the liquid, the electricity measurement device being connected to opposing ends of the carbon nanotube through the two electrodes.

58. A flow sensing device as in claim 57 wherein the flow sensing device generates electricity without an external power source.