Electrical response using nanotubes on a fibrous substrate

Patent metadata

Field	Value
Publication number	US-10031097-B1
Application number	US-201414195129-A
Country	US
Kind code	B1
Filing date	Mar 3, 2014
Priority date	Mar 5, 2013
Publication date	Jul 24, 2018
Grant date	Jul 24, 2018

Abstract

A device produces an electrical signal in response to a stimulus. The device is formed of a flexible substrate including a layer of fibers, for example, paper, and a solution of dispersed carbon nanotubes coated onto and within the fibers, the solution evaporated to leave carbon nanotubes intertwined within the layer of fibers. The carbon nanotubes are functionalized to be optimized for producing an electrical signal for a particular stimulus, where the stimulus includes exposure of the device to a particular gas or vapor. A number of such devices, some or all of which can be different, are housed together, for producing a complex electronic signal, or for sensing any of a wide variety of stimulus.

First claim

What is claimed is:

1. A system for estimating humidity present in a gas or vapor in a specified volume, the system comprising:
a fibrous substrate that is functionalized with at least one selected functionalizing substance, said substrate having a layer of fibers;
a plurality of carbon nanostructures that are intertwined with the layer of fibers in the substrate;
an electrical parameter value (EPV) measurement mechanism (EPVMM) that is electrically connected to the substrate at two or more spaced apart locations and that provides a measured EPV value that characterizes an electrical path between the two or more spaced apart locations;
a gas admission mechanism that exposes the substrate to a known gas or vapor that has an associated relative humidity value (RH) that is not yet known; and
a processor that receives a measured EPV for the known gas or vapor and that provides an estimate of relative humidity value of the known gas or vapor that corresponds to the measured EPV.

2. The system of claim 1 , wherein said nanostructures comprise single wall nanotubes and multi-wall nanotubes.

3. The system of claim 1 , wherein said fibrous substrate comprises at least one of cellulose paper, filter paper, porous paper, and biodegradable paper.

4. The system of claim 1 , wherein said substrate is doped with at least one selected dopant substance.

5. The system of claim 1 , wherein said functionalizing substance comprises at least one of carboxylic acid and an organic acid.

6. The system of claim 1 , wherein said EPV is chosen to be at least one of electrical current, electrical voltage difference, conductance, resistance, impedance, capacitance and inductance.

7. The system of claim 1 , wherein said known gas or vapor comprises at least one of NH 3 and NO 2 .

8. The system of claim 1 , wherein said carbon nanostructures are intertwined with the layer of fibers of said substrate by dispersing said nanostructures in a volatile solution, coating said substrate with the volatile solution, and allowing said volatile solution to evaporate from said substrate.

9. The system of claim 8 , wherein said volatile solution comprises at least one of dimethylformamide, dodecylbenezenesulfonate, and water.

10. A method for estimating humidity present in a gas or vapor in a specified volume, the method comprising:
functionalizing a fibrous substrate with at least one selected functionalizing substance, said substrate having a layer of fibers;
drop casting a plurality of carbon nanostructures with the layer of fibers of the substrate thereby intertwining the plurality of carbon nanostructures with the layer of fibers in the substrate;
providing electrical parameter value (EPV) measurement mechanism (EPVMM) that is electrically connected to the substrate at two or more spaced apart locations and that provides a measured EPV that characterizes an electrical path between the two or more spaced apart locations;
exposing the substrate to a known gas or vapor that has an associated relative humidity value (RH) that is not yet known; and
providing a processor that receives a measured EPV for the known gas or vapor and that provides an estimate of relative humidity value of the known gas or vapor that corresponds to the measured EPV.

11. The method of claim 10 , further comprising choosing said nanostructures to comprise single wall nanotubes and multi-wall nanotubes.

12. The method of claim 10 , further comprising choosing said fibrous substrate to comprise at least one of cellulose paper, filter paper, porous paper, and biodegradable paper.

13. The method of claim 10 , further comprising doping said substrate with at least one selected dopant substance.

14. The method of claim 10 , further comprising choosing said functionalizing substance to comprise at least one of carboxylic acid and an organic acid.

15. The method of claim 10 , further comprising choosing said EPV to be at least one of electrical current, electrical voltage difference, conductance, resistance, impedance, capacitance and inductance.

16. The method of claim 10 , further comprising choosing said known gas or vapor to comprise NH 3 and NO 2 .

17. The method of claim 10 , further comprising intertwining said carbon nanostructures with the layer of fibers of said substrate by dispersing said nanostructures in a volatile solution, coating said substrate with the volatile solution, and allowing said volatile solution to evaporate from said substrate.

18. The method of claim 17 , further comprising choosing said volatile solution to comprise at least one of dimethylformamide, dodecylbenezenesulfonate, and water.

19. A method for estimating a concentration of NH 3 present in a gas or vapor in a specified volume, the method comprising:
functionalizing a fibrous substrate with at least one selected functionalizing substance, said substrate having a layer of fibers;
drop casting a plurality of carbon nanostructures with the layer of fibers of the substrate thereby intertwining the plurality of carbon nanostructures with the layer of fibers in the substrate;
providing an electrical parameter value (EPV) measurement mechanism that is electrically connected to the substrate at two or more spaced apart locations and that provides a measured EPV that characterizes an electrical path between the two or more spaced apart locations;
exposing the substrate to a known gas or vapor that has an associated NH 3 concentration whose [NH 3 ] concentration value is not yet known; and
providing a processor that receives a measured EPV for the known gas or vapor and that provides an estimate of the [NH 3 ] concentration value of the known gas or vapor that corresponds to the measured EPV value.

20. The method of claim 19 , further comprising:
determining relative humidity RH of said known gas or vapor; and
increasing or decreasing said measured EPV by a compensation increment that varies approximately linearly with variation of the RH relative to a reference value of RH.

Assignees

• The Us Administrator Of The National Aeronautics & Space Administration Nasa
• Nasa

Inventors

• Han Jin-Woo
• Meyyappan Meyya

Classifications

• G01N27/223

  for determining moisture content, e.g. humidity (rain detectors on vehicle windows B60S1/0825) · CPC title

• Y10S977/953

  Detector using nanostructure · CPC title

• B82Y30/00

  Nanotechnology for materials or surface science, e.g. nanocomposites · CPC title

• B82Y15/00

  Nanotechnology for interacting, sensing or actuating, e.g. quantum dots as markers in protein assays or molecular motors · CPC title

• G01N27/121 Primary

  for determining moisture content, e.g. humidity, of the fluid (moisture content of the tested material G01N27/048) · CPC title