US Patent 7601205 - CNT field emission air filter

http://www.freepatentsonline.com/7601205.html

Ionic air filters are common but see limited use on the small scale due to the high voltage necessary to charge air. This patent from IBM teaches a carbon nanotube ionization air filter which may improve the energy efficiency and lead to scalability of such devices. Claim 1 reads:

1. An electrostatic, airborne particulate precipitator comprising:

a housing unit;

a first conductive electrode located in said housing unit;

a second conductive electrode located in said housing unit at a distance from said first conductive electrode, said first and second conductive electrodes comprising poles of an electrostatic field; and

a carbon nanotube formed on said second conductive electrode, wherein said carbon nanotube comprises a shape sufficient to ionize gas in said housing unit.