Nanomechanical oscillators — tiny strips of vibrating silicon only a few hundred atoms thick — are the subject of extensive study by nanotechnology researchers. They could someday replace bulky quartz crystals in electronic circuits or be used to detect and identify bacteria and viruses.
The catch is that measuring their vibrations isn’t easy. It is usually done by bouncing laser beams off them — which won’t work when the nanodevices become smaller than the wavelength of the light — or with piezoelectric devices — those bulky quartz crystals we’re trying to get rid of.
Now Cornell University [profile] researchers have come up with a very simple solution: reach out and touch them. The vibration of the tiny oscillators can be measured by “tapping” with an atomic force microscope (AFM).
An AFM uses a tiny probe that moves slowly just above a surface. Electrostatic attraction or repulsion between the atoms in the tip of the probe and those in the surface causes the probe to move up and down, creating an image of the surface so detailed that individual atoms show up as bumps. Alternatively, the AFM can be used in “tapping mode,” literally bouncing off the surface.
