Saturday, June 10, 2006

US Patent 7057203 - Metal Salt Treated Nanotube Electron Emitter

As mentioned in earlier postings, numerous patents have been granted based upon technologies exploiting electron emitting nanotubes. This patent teaches employing metal salts such as ionic alkali metals (Li, Na, K, Rb, Cs, Fr) to treat the electron nanotubes and enhance the emission.
Claim 1 reads:

1. A field emission apparatus comprising: a) a low pressure gaseous environment; and b) a cathode comprising: i. a substrate; and ii. a metal salt-treated carbon nanotube layer deposited on the substrate.

This is not the first patent employing metal treated nanotubes to enhance field based electron emission in a low pressure gaseous environment (see for example It is also not the first patent to treat nanotubes with metal salts (see The attorney argued against the use of the '697 patent in an obviousness rejection since the '697 patent included an embodiment directed toward battery structures. Even though the '697 patent clearly states that the alkali metal enhancement is useful for a number of diverse applications to provide the advantage of increasing the energy efficiency of nanotubes, the examiner was successfully convinced that the '697 nanotube patent was in a different field of endeavor then the '292 nanotube patent directed towards electron emission nanotubes. This is slightly problematic since one of ordinary skill in the nanotechnology art would likely consider the combined teachings of a variety of references concerned with nanotubes in determining what was obvious, regardless of whether particular embodiments were directed to a specific application. Unfortunately it seems that many patent examiners may not recognize the existence of a person of ordinary skill in the nanotechnology art and are thus unable to formulate proper obviousness rejections in terms of one of ordinary skill in nanotechnology. With the continued reluctance of the US patent office to create a centralized group of Examiners focusing on the growing volume of nanotech. patents these types of problems are likely to increase.