Acoustic Holograms that Levitate Particles

Tractor beams are mysterious rays that can grab and lift objects. The concept has been used by science-fiction writers, and programmes like Star Trek, but has since come to fascinate scientists and engineers. Researchers have now built a working tractor beam that uses high-amplitude sound waves to generate an acoustic hologram which can pick up and move small objects. The technique, published in Nature Communications, could be developed for a wide range of applications, for example a sonic production line could transport delicate objects and assemble them, all without physical contact.  On the other hand, a miniature version could grip and transport drug capsules or microsurgical instruments through living tissue. http://www.nanotechnologyworld.org/#!...