Tuesday, May 16, 2006

US Patent 7045108 - Carbon Nanotube Yarn


Carbon nanotubes, entangled within a binding material, are known to be useful for a variety of purposes including forming electromagnetic shielding material or a bulletproof material (see US Patent 6265466 and US Patent 7041372). However, the length of individual nanotubes is usually limited to a few hundred microns which limits the potential of such applications. This patent proposes a method to produce longer nanotubes by end to end bonding of smaller nanotubes.

Claim 1 reads:

1. A method of fabricating a carbon nanotube yarn comprising: (1) forming a carbon nanotube array; and (2) drawing out a bundle of carbon nanotubes from said carbon nanotube array such that a carbon nanotube yarn is formed.

Claim 12 reads:

12. A carbon nanotube yarn comprising a plurality of carbon nanotube bundles which are joined end to end by van der Waals attractive force, wherein each of the carbon nanotube bundles comprises a plurality of carbon nanotubes substantially parallel to each other.

There are a few interesting things about this patent (besides the breadth of the claims). For one thing, the Examiner did not present any rejection during prosecution but rather issued an immediate allowance. This is fairly rare, especially in cases where broad claims are presented for examination. In the Reasons for Allowance the Examiner cited some prior art disclosing nanotube rope formed from entangled nanotubes or nanotubes joined by side to side van der Waals forces in contrast to the claimed "end-to-end" feature of claim 12. Another interesting thing about this patent is that the assignees (patent owners) are based in China. China has not commonly been thought of a large patent player when compared to the US, Europe, and Japan. However, this is one of a series of patents from China that is indicative of China's intention of becoming a serious player in the nanotech patent field.

While not specifically addressed in the patent one other application of this patent, besides EM shielding and bulletproof material, may be something that has come up in science fiction and by some futurists -space elevators.