Fibers that can detect and produce sound have been developed by scientists at MIT’s Research Lab of Electronics.

How it works

The heart of the new acoustic fibers is a plastic commonly used in microphones. By playing with the plastic’s fluorine content, the researchers were able to ensure that its molecules remain lopsided — with fluorine atoms lined up on one side and hydrogen atoms on the other — even during heating and drawing. The asymmetry of the molecules is what makes the plastic “piezoelectric,” meaning that it changes shape when an electric field is applied to it.

In a conventional piezoelectric microphone, the electric field is generated by metal electrodes. But in a fiber microphone, the drawing process would cause metal electrodes to lose their shape. So the researchers instead used a conducting plastic that contains graphite, the material found in pencil lead. When heated, the conducting plastic maintains a higher viscosity — it yields a thicker fluid — than a metal would.

The same mechanism that allows piezoelectric devices to translate electricity into motion can work in reverse, generating electricity.

Applications

Wearable microphones

Biological sensors

Loose nets that monitor the flow of water in the ocean Large-area sonar imaging systems with much higher resolutions: A fabric woven from acoustic fibers would provide the equivalent of millions of tiny acoustic sensors.

More info: MIT news