Thursday, May 25, 2006

US Patent 7048901 - Electrical Connection to DNA Using Nanotube

There is some interest in the use of biopolymers such as DNA, RNA, and proteins as electrical circuit elements. However, there is difficulty in forming electrical connections between metallic electrodes and biopolymers due to oxide formation on metal electrodes. This patent addresses this problem by using nanotubes instead of metallic electrodes as the connection element.

Claim 1 reads:

1. A production method of an electrical connection structure, the method comprising the steps of: operating at least one carbon nanotube as an electrode to an arbitrary portion of a biopolymer; and contacting the electrode with the biopolymer at the arbitrary portion; wherein the electrode and the biopolymer are fixed together in a stable electrically connected state by the contacting step.

Originally the applicant presented corresponding claims to the biopolymer/nanotube electrical connection structure in addition to the production method. The Examiner applied prior art in which a biopolymer was attached to a nanotube via an intermediate gold layer. Unfortunately for the applicant, the description of "nanotube" in the specification was specifically broad to include modified nanotubes and the attorney was unable to overcome the rejections to the structure claims resulting in these claims cancellation.

Often patent attorneys fear that writing patent specifications that are too narrow may unduly limit the applicant's invention. This case represents an example of how writing specifications that are too broad sometimes have the same effect.