Mechanical resonators are widely used as inertial balances to detect small quantities of adsorbed mass through shifts in oscillation frequency. Advances in lithography and materials synthesis have enabled the fabrication of nanoscale mechanical resonators, which have been operated as precision force, position and mass sensors. Here we demonstrate a room-temperature, carbon-nanotube-based nanomechanical resonator with atomic mass resolution. This device is essentially a mass spectrometer with a mass sensitivity of 1.3 × 10-25 kg Hz-1/2 or, equivalently, 0.40 gold atoms Hz-1/2. Using this extreme mass sensitivity, we observe atomic mass shot noise, which is analogous to the electronic shot noise measured in many semiconductor experiments. Unlike traditional mass spectrometers, nanomechanical mass spectrometers do not require the potentially destructive ionization of the test sample, are more sensitive to large molecules, and could eventually be incorporated on a chip.
Bibliographical noteFunding Information:
We thank B. Aleman for technical assistance. This work was supported by the Director, Office of Energy Research, Office of Basic Energy Sciences, Materials Sciences and Engineering Division, of the US Department of Energy under contract DE-AC02-05CH11231, which provided nanotube synthesis, detailed TEM characterization and UHV testing of the nanomechanical mass spectrometer. It was also supported by the National Science Foundation within the Centre of Integrated Nanomechanical Systems, under grant EEC-0425914, which provided for design and assembly of the spectrometer. K.K acknowledges support from a Samsung Graduate Fellowship.
All Science Journal Classification (ASJC) codes
- Atomic and Molecular Physics, and Optics
- Biomedical Engineering
- Materials Science(all)
- Condensed Matter Physics
- Electrical and Electronic Engineering