US Patent 7814776 - CNT-Quartz resonator

http://www.freepatentsonline.com/7814776.html

This patent teaches a way to measure mass with a resolution of femtograms (1 femtogram = 1 millionth of a nanogram) using a nanotube coated micromachined quartz crystal. Claim 1 reads:

1. A method for increasing the quality factor of at least one sensor comprising:

adding a layer of nanotubes to the at least one sensor to thereby increase the quality factor of the at least one sensor and form a nanotube-coated device;

placing the nanotube-coated device in a vacuum chamber for a period of time sufficient to further increase the quality factor of the at least one sensor.