Sensing water vapour

Patent metadata

Field	Value
Publication number	US-2017184530-A1
Application number	US-201715456567-A
Country	US
Kind code	A1
Filing date	Mar 12, 2017
Priority date	Sep 19, 2011
Publication date	Jun 29, 2017
Grant date	—

Abstract

A water vapour sensor comprises a substrate and a film of carbon nanotubes impregnated with surfactant on the substrate. The substrate is of material which is inert relative to the film. Two or mote electrical conductors are in contact with in spaced apart zones of the film, whereby the impedance of the film may be measured. The sensor is housed in housing which protects the sensor but also allows exposure of the film to water vapour.

First claim

1 - 12 . (canceled)

13 . A method of making a water vapour sensor comprising:
depositing a liquid containing carbon nanotubes impregnated with surfactant on an inert substrate; drying the liquid on the substrate to form a film of carbon nanotubes impregnated with surfactant on the substrate; and connecting spaced apart zones of the film to electrical conductors.

14 . A method according to claim 13 , comprising removing surfactant from the zones.

15 . A method according to claim 13 , wherein the surfactant is SDS (sodium dodecyl sulphate), SDBS (sodium dodecyl benzene sulfonate), CTAB (Hexadecyl Trimethyl Ammonium Bromide), or polyethylene glycol p-(1,1,3,3-tetramethylbutyl)-phenyl ether.

16 . A method according to claim 15 , comprising impregnating the carbon nanotubes with surfactant.

17 . A method according to claim 16 , wherein the impregnating includes:
mixing carbon nanotubes in a solution of surfactant and deionized water; and sonicating the mixture of carbon nanotubes and surfactant without removing the surfactant.

18 . A method according to claim 17 , wherein the mixing includes mixing single walled carbon nanotubes in a solution of surfactant and deionized water containing a concentration of surfactant above a critical micelle concentration.

19 . A method according to claim 18 , wherein the depositing includes spraying the mixture of carbon nanotubes and surfactant on to a heated polyethylene terephthalate substrate.

20 . A humidity sensor comprising:
carbon nanotubes impregnated with a surfactant; a measuring device operatively connected to the impregnated nanotubes to measure an electrical resistance of the impregnated nanotubes; and a processor operatively connected to the measuring device to determine a humidity based on the measured resistance.

21 . The humidity sensor of claim 20 , wherein the impregnated nanotubes comprise a mixture of metallic and semiconductive carbon nanotubes impregnated with the surfactant.

22 . The humidity sensor of claim 21 , wherein the impregnated nanotubes comprise single walled carbon nanotubes, multiwalled carbon nanotubes, or a mixture of single and multiwalled carbon nanotubes impregnated with the surfactant.

22 . The humidity sensor of claim 22 , comprising a substrate supporting the impregnated nanotubes, the substrate being inert to the impregnated nanotubes.

23 . The humidity sensor of claim 20 , comprising a temperature sensor operatively connected to the impregnated nanotubes to sense the temperature of the impregnated nanotubes, and wherein the processor is operatively connected to the temperature sensor to determine the humidity based on the measured resistance and the sensed temperature.

24 . A dew point sensor, comprising:
a cooler; a film of carbon nanotubes impregnated with a surfactant operatively connected to the cooler; a measuring device to measure an electrical resistance of the film of carbon nanotubes; a temperature sensor to sense a temperature of the film of carbon nanotubes; and a processor operatively connected to the measuring device and the temperature sensor to determine a dew point bases on the measured resistance and the sensed temperature.

25 . The dew point sensor of claim 24 , wherein the cooler includes a cooled face and the film of carbon nanotubes is disposed directly on the cooled face.

26 . The dew point sensor of claim 24 , wherein the film of carbon nanotubes includes a mixture of metallic and semiconductive nanotubes impregnated with the surfactant.

27 . The dew point sensor of claim 24 , wherein the film of carbon nanotubes includes single walled nanotubes, multiwalled nanotubes, or a mixture of single and multiwalled nanotubes impregnated with the surfactant.

Assignees

• Hewlett Packard Development Co Lp

Inventors

• Scott Graeme
• Coull Richard
• Scardaci Vittorio

Classifications

• G01N25/02

  by investigating changes of state or changes of phase; by investigating sintering {(investigating or analysing oils or hydrocarbon fluids by measuring cloud point or pour point G01N33/2811)} · CPC title

• G01N27/127 Primary

  comprising nanoparticles · CPC title

• G01N27/121

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

• B05D3/0254

  After-treatment · CPC title