World's most sensitive scales detect a yoctogram

How do you weigh an atom down to the last proton? With scales accurate enough to measure the smallest unit of mass, aka the yoctogram, which is just one septillionth of a gram.

No ordinary scales will do ? the tiniest weights are measured using nanotubes, which vibrate at different frequencies depending on the mass of the particles or molecules on them. Until now, 100 yoctograms ? or a tenth of a zeptogram ? was the smallest mass the most sensitive sensor could detect.

To go even lower, Adrian Bachtold and his colleagues at the Catalan Institute of Nanotechnology in Barcelona, Spain, used short nanotubes. They give the best resolution and work at the low temperatures thought best for measuring frequency. Although the equipment was placed in a vacuum to minimise interference from other atoms, Bachtold removed any stray atoms by temporarily turning up the heat on the tubes to disrupt any bonds to atoms.

Then the sensor was able to weigh an atom of xenon to the nearest yoctogram, or 10^-24 grams. This makes it the first scale capable of detecting a single proton, which weighs in at 1.7 yoctograms.

"The yoctogram mass sensitivity achieved by the Catalan team is certainly spectacular ? the challenge ahead will be to routinely manufacture nanotube sensors at low cost," says Rachel McKendry, a nanoscientist at University College London.

Bachtold hopes the scales could be used to distinguish different elements in chemical samples, which might differ only by a few protons. They might also diagnose health conditions by identifying proton-scale differences in molecular mass that are markers of disease.

Journal reference: Nature Nanotechnology, DOI: 10.1038/NNANO.2012.42

If you would like to reuse any content from New Scientist, either in print or online, please contact the syndication department first for permission. New Scientist does not own rights to photos, but there are a variety of licensing options available for use of articles and graphics we own the copyright to.

Have your say

Only subscribers may leave comments on this article. Please log in.

Only personal subscribers may leave comments on this article

Subscribe now to comment.

All comments should respect the New Scientist House Rules. If you think a particular comment breaks these rules then please use the "Report" link in that comment to report it to us.

If you are having a technical problem posting a comment, please contact technical support.

cpac straw poll breaking dawn part 2 breaking dawn part 2 whitney cummings msnbc i will always love you maine caucus