Carbon nanotube-enhanced capillary condensation for capacitive humidity sensor

• graphics and graphs for several types of humidity sensors
• companies
  • list of companies that make/distribute/service humidity sensors
  • another list
  • another list
  • great spreadsheet
  • http://content.honeywell.com/sensing/prodinfo/humiditymoisture/
  • http://www.humirel.com/accueil.php
  • http://www.preconusa.com/humidity_moisture_dew_sensors.htm
  • http://www.sensirion.com/en/02_sensors/03_humidity/00_humidity_temperature_sensor/00_humidity_sensors.htm
  • http://www.smartec.nl/humidity_sensor.htm
  • http://www.gefran.com/en/categories/category_81.aspx
  • http://www.ist-ag.com/english/products/humid/humidity.html
  • http://www.temperatures.com/dewvendors.html
  • http://www.parallax.com/detail.asp?product_id=28018
  • http://www.rotronic-usa.com/v2/hyclip/hygromer.htm
  • http://www.meas-spec.com/myMSI/sensors/humidity.asp
  • bigcos appear to be sensirion, humirel, honeywell?
  • more for earth sci?
    • http://www.novalynx.com/products-temperature-humidity.html
    • http://www.thermalogic.com/pages/humisense.html?referrer=google&gclid=COC1p7DKzogCFRFdQAod520j8w

moisture sensing used in (now and/or future):

• portable biomedical, pharmaceutical diagnosis microsystems {1}
• respiration
• wireless sensor networks {2}
• both of above need sensors of small size and high sensing resolution
• hydrogen fuel cells
• "Typical applications for humidity sensors include automotive, appliances, HVAC and medical." src
• "automotive, industrial and medical marketplaces" src

competition: top of pg2

CNTs can offer the possibility of excellent sensitivity and rapid response times,

since their high surface area to volume ratio 16,17 is well-suited for physical adsorption or chemical interaction

with targeted measurands to transduce higher and faster electrical sensing signals.

multiwalled nanotubes are either cyclindars in cylindars or, or a long sheet rolled wikipedia

randomly aligned MWCNTs can naturally form networks of porous-like nano-structures p2

how it works: The increased transduction is caused by the change in the effective dielectric that is governed by the

varying percentages of air and water within the CNT-enhanced sensor. The change in the effective dielectric

value,

’, will cause a measured change in capacitance that is proportional to the change in relative humidity

The amplified capacitance responses or high sensing resolutions

can be extended to the low RH range by controlling the onset point of induced capillary condensation through

various nano-materials, pore sizes and their distribution. p15

work supported by nserc

-tested at RH 50-85% - what about other values?

-patent info: dates of filing, costs (who paid), who owns it

-also dates of how long research took, etc

-state of funding, who paid for research, etc

-can get data to make own graphs?

-can it be used to measure concentrations of things other than water?

-future work/direction; could regular arrangement be better than random tubes (more $?)

-how much to manufacture?

-why bought nanotubes from X? vs other options?

-can get photos from pg4 (raw photos, without the "a" and "b" on them)

-hmn, will the licensed companies buy them or make them... ?

advantages

-size (how ?) - why good?

-larger range of detection

-more sensitive

-speed? "

"Current commercial humidity sensors need at least five seconds to detect humidity changes. We've been able to see changes in less than half a second, which makes our device one of the fastest in the world," Steele added." src

drawbacks

-any?

http://hyperphysics.phy-astr.gsu.edu/hbase/electric/pplate.html