A robot arm that can pick up and carry objects without touching them using ultrasonic levitation is being developed by scientists. Researchers at ETH Zurich used an array of tiny speakers that emit sound at tightly controlled frequencies and volumes in order to'grip' an object. The sound waves from the speakers create a pressure field that holds an object up - a kind of'acoustic levitation', according to researcher Marcel Shuck. Dr Shuck says the acoustic gripper will be ideal for delicate tasks such as assembling watches or microchips, where any damage from touch marks would cost money. The sound waves used to levitate an object can also move it around by having audio coming from multiple directions, the team says.