MIT engineers have devised a way to measure the mass of particles with a resolution better than an attogram（微微微克） -- one millionth of a trillionth of a gram. Weighing these tiny particles, including both synthetic nanoparticles and biological components of cells, could help researchers better understand their composition and function. The system builds on a technology previously developed by Scott Manalis, an MIT professor of biological and mechanical engineering, to weigh larger particles, such as cells. This system, known as a suspended microchannel resonator (SMR), measures the particles' mass as they flow through a narrow channel.

By shrinking the size of the entire system, the researchers were able to boost its resolution to 0.85 attograms -- more than a 30-fold improvement over the previous generation of the device.

"Now we can weigh small viruses, extracellular（细胞外的） vesicles（囊泡）, and most of the engineered nanoparticles that are being used for nanomedicine," says Selim Olcum, a postdoc in Manalis' lab and one of the lead authors of a paper describing the system in this week's issue of the Proceedings of the National Academy of Sciences.

Graduate student Nathan Cermak is also a lead author of the paper, and Manalis, a member of MIT's Koch Institute for Integrative Cancer Research, is the paper's senior author. Researchers from the labs of MIT professors and Koch Institute members Angela Belcher and Sangeeta Bhatia also contributed to the study.