MIT Scale Can Weigh Individual Nanoparticles With Single Attogram Precision

Posted on January 26, 2014

MIT engineers have developed a suspended nanochannel resonator (SNR) that can measure nanoparticles with single attogram precision. An attogram is one millionth of a trillionth of a gram. The new system builds on technology previously developed by Scott Manalis, an MIT professor of biological and mechanical engineering. It measures the mass of a particle as its flows through a narrow channel. Engineers have boosted resolution of the SNR system to 0.85 attograms. A research paper on the technology was published here in the Proceedings of the National Academy of Sciences.

Selim Olcum, a postdoc in Manalis' lab and one of the lead authors of the paper, says in the announcement, "Now we can weigh small viruses, extracellular vesicles, and most of the engineered nanoparticles that are being used for nanomedicine."

The system is a fluid-filled microchannel etched in a tiny silicon cantilever that vibrates inside a vacuum cavity. Cells and particles flow through the channel one at a time. As they pass through their mass slightly alters the cantilever's vibration frequency. Scientists can this use this change in frequency to determine the mass of the particle. The MIT scientists say the cantilever behaves like a diving board. To improve the system the scientists made the cantilever even smaller. It is now just 22.5 microns long. The scientists also the source for the cantilever's vibration from an electrostatic to a piezoelectric excitation.

Olcum says, "If you're measuring nanoparticles with a large cantilever, it's like having a huge diving board with a tiny fly on it. When the fly jumps off, you don't notice any difference. That's why we had to make very tiny diving boards."

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