"MOVE over microphones, nanophones have arrived. A gold sphere just 60 nanometres in diameter is the most sensitive listening device ever created, paving the way for soundtracks to formerly silent movies of bacteria and other single-celled organisms.
Alexander Ohlinger at Ludwig Maximilian University in Munich (LMU), Germany, and colleagues suspended gold nanoparticles in a drop of water. They trapped one sphere in a laser beam and then fired rapid pulses of light from a second laser at others a few micrometres away. The pulses heated the nanoparticles, which disturbed the water around them, generating pressure, or sound, waves."
Gold nano 'ears' set to listen in on cells - health - 13 January 2012 - New Scientist