Innovation: coils made of liquid metal for future hearing aids.


© Adam Ciesielski - Sxc

Scientists from Korea University in Seoul have developed a stretchable acoustic device by using a deformable, liquid metal coil. Until now, acoustic devices have basically relied on rigid metal coils that can both emit and detect sound. Scientists have however been looking for ways to develop flexible electronics, such as batteries, video displays, and solar panels. The challenge has been to ensure that audio components remain mechanically stable after they are stretched.

Korean researchers, specializing in chemistry and engineering, are following a new approach that aims at using coils made of liquid metal to either detect or emit sound. Their new coil is made of galinstan, a highly conductive liquid metal alloy composed of gallium, indium and tin. They used a syringe to inject galinstan into a spiral channel in a thin film of flexible silicone rubber. By attaching copper wires to the end of the coil and a neodymium magnet to the center of the coil and charging the device electrically, the scientists were able to record sounds such as the human voice and an alarm clock, and play the sounds back while the device was attached to the wrist or was being stretched by hand.

The novel device could be stretched up to 50% of its length and up to 2,000 times without any noticeable loss of acoustic performance. “Our stretchable loudspeaker can give off the sound level of typical earphones,” says study co-author Jeong Sook Ha. Potential uses for this device include “body-attachable and wearable acoustic applications such as sensing biological signals, hearing aids, and notification of information via sound,” he adds.

Source: Live Science