Sound waves put levitation on the move

Levitating objects can spin, glide and collide together — no magnets or magic tricks required.

Using steady streams of sound waves, engineers maneuvered hovering toothpicks, coffee granules and water droplets through the air, a team from ETH Zurich reports July 15 in the Proceedings of the National Academy of Sciences. Scientists could use the touch-free technique to gently handle delicate or hazardous lab chemicals or to avoid contaminating cells in biological experiments.

“It’s a beautiful piece of work,” says Penn State bioengineer Tony Jun Huang, who has used sound to manipulate particles in liquid. In a single device, the study’s authors can move two airborne particles in different directions or make them converge. No one has done that before, Huang says.