Listening In by Nanoparticle

摘要

The degree of control with which particles can be trapped, rotated, pulled apart, and manipulated by focused light beams has made optical tweezers an extremely useful laboratory tool across many dis- ciplines-from probing the mechanical properties of cells and DNA to building three-dimensional structures and cooling gases to their quantum ground state. It might be expected that external perturbation or excitement would produce a wobble of a light-trapped particle. Ohlinger ef al. exploit this effect to show that a trapped qold nanoparticle can be used as an ultrasensitive detector of sound waves. A typical empty room has a sound level of 20 decibels. By comparison, the trapped gold nanoparticle can detect sounds down to -60 decibels-over six orders of magnitude more sensitive than the human ear.