Moving Particles with Sound Waves

Sound waves can be powerful - powerful enough to move large groups of particles. Recently, scientists at the Chinese Academy of Sciences announced an acoustic sieve that can sift, move, trap, or align large groups of particles by size and density under water.They began by focusing an ultrasound beam on a flat plate. The brass plate has a grating on top made of materials (phononic crystals) specifically for manipulating acoustic waves. Below the plate is a container of glass spheres of various si...