Carbon nanotube temperature and pressure sensors

• US 9,476,785 B2
• Filed: 09/24/2013
• Issued: 10/25/2016
• Est. Priority Date: 08/26/2009
• Status: Active Grant

• Current Assignee: UT-Battelle LLC
• Original Assignee: UT-Battelle LLC
• Inventors: Ivanov, Ilia N., Geohegan, David B.
• Primary Examiner(s): KAPLAN VERBITSKY, GAIL
• Application Number:
  US14/035,097
• Publication Number:
  US 20140020471A1
• Time in Patent Office: 1,127 Days
• Field of Search: 374/143, 374/185, 374/184, 374/178, 977/700
• US Class Current: 1/1
• 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: G01K 2211/00 Thermometers based on nanotechnology
• CPC Class Codes: G01K 7/00 Measuring temperature based on the use of electric or magnetic elements directly sensitive to heat giving results other than momentary value of temperature G01K3/00 ; Power supply therefor, e.g. using thermoelectric elements
• CPC Class Codes: G01K 7/021 Particular circuit arrangements G01K7/026, G01K7/12, G01K7/14 take precedence
• CPC Class Codes: G01K 7/028 using microstructures, e.g. made of silicon
• CPC Class Codes: G01K 7/18 the element being a linear resistance, e.g. platinum resistance thermometer G01K7/26 takes precedence
• CPC Class Codes: G01L 1/20 by measuring variations in ohmic resistance of solid materials or of electrically-conductive fluids of piezo-resistive materials G01L1/18; by making use of electrokinetic cells, i.e. liquid-containing cells wherein an electrical potential is produced or varied upon the application of stress
• CPC Class Codes: G01L 19/00 Details of, or accessories for, apparatus for measuring steady or quasi-steady pressure of a fluent medium insofar as such details or accessories are not special to particular types of pressure gauges
• CPC Class Codes: G01L 9/00 Measuring steady of quasi-steady pressure of fluid or fluent solid material by electric or magnetic pressure-sensitive elements G01L11/004 takes precedence; Transmitting or indicating the displacement of mechanical pressure-sensitive elements, used to measure the steady or quasi-steady pressure of a fluid or fluent solid material, by electric or magnetic means measuring differences of two or more pressure values G01L13/00; measuring two or more pressure values simultaneously G01L15/00
• CPC Class Codes: G01L 9/0001 Transmitting or indicating the displacement of elastically deformable gauges by electric, electro-mechanical, magnetic or electro-magnetic means G01L9/0026, G01L9/0033, G01L9/0082, G01L9/0089, G01L9/0091 take precedence
• CPC Class Codes: G01L 9/0002 using variations in ohmic resistance G01L9/0051 takes precedence
• CPC Class Codes: G01L 9/0005 using variations in capacitance G01L9/0072 takes precedence
• CPC Class Codes: Y10S 977/742 Carbon nanotubes, CNTs
• CPC Class Codes: Y10S 977/955 Of thermal property
• CPC Class Codes: Y10S 977/956 Of mechanical property

Abstract

The present invention, in one embodiment, provides a method of measuring pressure or temperature using a sensor including a sensor element composed of a plurality of carbon nanotubes. In one example, the resistance of the plurality of carbon nanotubes is measured in response to the application of temperature or pressure. The changes in resistance are then recorded and correlated to temperature or pressure. In one embodiment, the present invention provides for independent measurement of pressure or temperature using the sensors disclosed herein.

Claims

1. A pressure sensor comprising:

a plurality of sets of flexible membranes, the plurality of sets of flexible membranes are layered in a first direction, each adjacent set being separated in the first direction by a distance prior to application of pressure, each set of flexible membranes includes at least two membranes, where each flexible membrane includes electrically interconnected nanostructures; and

a power source to the electrically interconnected nanostructures, wherein an external force applied to the pressure sensor deforms at least one of the plurality of set of flexible membranes where adjacent flexible members of the at least two members in the at least one of the plurality of sets contact, wherein changes in the electrical properties of the at least one of the plurality of sets of flexible membranes that results from the external force is correlated to a pressure value for the external force.

2. A method of measuring pressure comprising:

providing a sensor element including a plurality of nanostructures having electrical junctions;

applying a current through the plurality of nano structures;

measuring electrical properties of the plurality of nanostructures in response to an application of pressure that increases or decreases a number of electrical junctions in the plurality of nanostructures in the sensor element; and

correlating the electrical properties of the plurality of nanostructures to pressure, wherein the nanostructures are carbon nanotubes having a purity of greater than 90% and wherein an increase in temperature of the nanostructures from 24°

to 100°

C. produces an increase in resistance of 0.5% or less.

3. The pressure sensor of claim 1, wherein each set of flexible membranes is coupled to a respective detector.

4. The pressure sensor of claim 3, wherein the respective detector indicates pressure at a respective set of flexible membranes.

5. The pressure sensor of claim 1, wherein when the pressure in the first direction increases, the number of the plurality of sets of flexible membranes being deformed increases.

6. The pressure sensor of claim 1, wherein the plurality of sets of flexible membranes is encased in a flexible substrate.

7. The pressure sensor of claim 3, wherein each respective detector detects a different pressure value.

8. The pressure sensor of claim 1, wherein the distance between adjacent flexible membranes of the at least two flexible membranes is between 5 nm and 100 nm prior to an application of pressure.

9. The pressure sensor of claim 1, wherein the distance between adjacent sets of the plurality of sets of flexible membranes prior to an application of pressure is greater than the less the distance between adjacent flexible membranes in the same set of the plurality of sets of flexible membranes prior to an application of pressure.

10. A sensor comprising:

a substrate;

a first sensor element present on a first portion of the substrate comprised of a first plurality nanostructures having a fixed number of electrical junctions, wherein resistance or capacitance of the electrically interconnected carbon nanotubes is correlated to temperature independent of pressure; and

a second sensor element present on a second portion of the substrate composed of a second plurality of nanostructures in which the number of electrical junctions in the second plurality of nanostructures varies with changes in pressure that is applied to the second sensor element, wherein resistance or capacitance of the second plurality of carbon nanotubes is correlated to pressure, the first portion and the second portion being separate and non-overlapping regions of the substrate.