Nanowires Get Plucked

On June 6, the 151st meeting of the Acoustic Society of America took place. While this may sound like a collection of folk singers, it's actually a serious scientific organization and at their meeting researchers will announce their success at causing vibrations in nanowires.

The team from Boston University developed the technique of coating silicon nanowires in a thin layer of chromium, making them light sensitive. They can then use a laser to pluck the string. Just like a tiny musical instrument, the nanowire vibrates at a frequency determined by mass, length, structure and tension.

As tiny particles, such as atoms, viruses, or various molecules, land on the wire, the change in the vibration can be used to weigh the particles. The team used a similar means to measure 30 xenon atoms earlier in 2006, although this required high power magnets. This process is much simpler and could be incorporated into sensitive equipment to monitor the concentration of particles in the air.

The full article is available at New Scientist and a recent paper in Applied Physics Letters.