Cornell NEMS device Weighs a Single DNA Molecule

karvind writes "Cornell researchers have refined their NEMS device to detect a single DNA molecule and can even count the number of DNA molecules attached to a single receptor by noting the difference in mass. The researchers used the Cornell Nanoscale Facility to create arrays of tiny cantilever oscillators 3 to 5 microns long and 90 nanometers thick on silicon chips. The principle underlying the mass-detection devices is that the frequency at which a solid object vibrates varies with its mass. In the reported experiments, the change in mass of 1 attogram was enough to shift the frequency of vibration by 50 Hz or more, depending on the size of the oscillator. This allowed the researchers not only to detect the binding of DNA molecules, but also to count the number of molecules attached to a single receptor by the total frequency shift. Results are reported in the latest issue of Nano Letters. " (Here's an earlier Slashdot story about weighing molecules by Caltech Researchers.)