Weighing nanoparticles and viruses using suspended nanochannel resonators

We have batch fabricated suspended nanochannel resonators (SNRs) to improve the mass resolution of suspended microchannel resonators (SMRs). The SNR consists of a cantilever that is 50 µm long, 10 µm wide, and 1.3 µm thick, with an embedded nanochannel that is 2 µm wide and 700 nm tall. The SNR has a resonance frequency near 640 kHz and exhibits the maximum quality factor of approximately 16,000 when dry and when filled with water. Using the SNRs, we demonstrated mass measurements of various nanoparticles down to 20 nm in diameter and viruses in solution with a resolution of 27 ag in a 1 kHz bandwidth, which represents a 100-fold improvement over existing SMRs and, to our knowledge, is the most precise mass measurement in liquid today.