US Patent 8216542 - Nanotube separation using microwaves

http://www.freepatentsonline.com/8216542.html

This patent from the Korea Institute of Machinery and Materials teaches a way to remove metallic nanotubes from a mixture of carbon nanotubes to produce high purity semiconducting nanotubes. Claim 1 reads:

1. A method for separating semiconducting nanotubes from a nanotube mixture comprised of semiconducting nanotubes and metallic nanotubes, comprising:

dispersing the nanotube mixture into a liquid medium selected from water and ethanol and then applying the dispersion to a substrate made of a material selected from an insulating material or a nonpolar polymer;

selectively heating at least part of the metallic nanotubes in the nanotube mixture by applying microwave radiation to the nanotube mixture after a material comprising carbon black is arranged under the nanotube mixture; and

removing the metallic nanotubes.