US 11,719,660 B1
Solid state carbon dioxide sensor
Jing Li, San Jose, CA (US); and Ami Milan Hannon, Scotts Valley, CA (US)
Assigned to United States of America as Represented by the Administrator of NASA, Washington, DC (US)
Filed by United States of America as Represented by the Administrator of NASA, Washington, DC (US)
Filed on Jul. 9, 2020, as Appl. No. 16/924,998.
Claims priority of provisional application 62/936,379, filed on Nov. 15, 2019.
Int. Cl. G01N 27/12 (2006.01); G01N 33/00 (2006.01)
CPC G01N 27/127 (2013.01) [G01N 33/004 (2013.01)] 5 Claims
OG exemplary drawing
 
1. A method of fabricating a sensor for sensing carbon dioxide (CO2), comprising: providing a substrate; disposing a pair of electrodes on the substrate; providing a predetermined amount of multi-walled carbon nanotubes (MWCNTs); oxidizing the MWCNTs with a mixture of acids at a first predetermined temperature and for a first predetermined amount of time; diluting, decanting and centrifuging the oxidized multi-walled carbon nanotubes (O-MWCNTs); rinsing the O-MWCNTs in water to produce purified O-MWCNTs; drying the purified O-MWCNTs at a second predetermined temperature for a second predetermined amount of time to produce purified O-MWCNTs in dry powder form; forming a solution consisting of water, the purified O-MWCNTs in dry powder form and iron oxide (Fe2O3) nanoparticles so as to produce a uniform suspension; depositing the uniform suspension onto the electrodes; and thereafter, baking the substrate so as to transform the uniform suspension into a dry (CO2) sensing material.