Adrian Bachtold at the Catalan Institute of Nanotechnology in Barcelona has created the world's most sensitive scale. The new subatomic weight scale can measure masses as tiny as one yoctogram
, less than the mass of a proton. From the article: "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."