A. Marzo, B. Drinkwater and S. Subramanian © 2015
A new (ultra)sound system keeps small objects suspended in midair and maneuvers them with unprecedented control.
Millimeter-sized plastic beads hover, spin, move around and get reeled in as if pulled by a tractor beam when placed in range of an ultrasound-blasting platform. The technique, described October 27 in Nature Communications, enables scientists to manipulate objects hands-free and perhaps eventually to poke and prod cells inside the body.
Scientists in Spain and England tiled a platform with dozens of speakers that emitted 40-kilohertz sound waves, beyond the range of human hearing. Interfering waves form three-dimensional acoustic fields, which the researchers harnessed to trap and manipulate the beads. Previous experiments achieved 3-D control by surrounding the target object with multiple speaker platforms, while the new setup requires just one.
Watch an acoustic tractor beam in action.
Video: A. Marzo, B. Drinkwater and S. Subramanian © 2015