US Patent 7279337 - Nucleic acid sequencing using modulation signal

http://www.freepatentsonline.com/7279337.html

Rapid sequencing of nucleic acids has been achieved via the use of nanopores which provide a channel for a molecular strand to pass through and be detected. This patent from Agilent Technologies teaches a method and apparatus that employs a modulated bias voltage and a detection of tunneling current in such a sequencing operation. Claim 1 reads:

1. A method of sequencing molecules of a polymer, comprising the steps of: centering a fixed bias voltage across a pair of nano-electrodes separated by a channel therebetween, the bias voltage corresponding to an energy difference between any two internal energy levels of a molecule of interest; modulating the bias voltage with a modulation waveform; sequentially urging the molecules of a polymer comprised of linked molecules including at least one of the molecules of interest through the channel; deriving an electrical signal indicative of the molecule of interest from tunneling current through the molecule of interest measured while the molecule of interest is between the nano-electrodes as the polymer passes through the channel; and identifying the molecule of interest by comparing the derived electrical signal to known values of the signal for the molecule of interest.