US Patent 7731930 - Double walled CNT assembly

http://www.freepatentsonline.com/7731930.html

Double-walled carbon nanotubes are the simplest form of conductive multiwalled nanotubes having optimum characteristics for field emission used in displays and biological or chemical sensors. This patent from Nikon includes some basic claims to CVD grown nanotubes containing a high percentage of double walled nanotubes. Claim 1 reads:

1. A carbon nanotube assembly directly grown on a substrate, wherein a proportion of double-walled carbon nanotubes to carbon nanotubes contained in the assembly is 70% or more.