Fabrics to interact with their environment

Research scientists at the Massachusetts Institute of Technology are singing a new tune with a new type of interactive fiber that has the ability to detect and create sound. For associate professor Yoel Fink and his team at MIT's Research Lab of Electronics, the threads used in textiles and even optical fibers are too passive to be truly useful. It may have taken a decade, but the researchers have finally developed a far more sophisticated version, one that enables fabrics to interact with their environment.
SOUND OFF

Featured in the August issue of Nature, the acoustic fibers have innumerable potential applications, from microphone-like clothes that capture speech or monitor bodily functions to microscopic filaments that can measure blood flow or brain pressure.
The fibers could be used to create microphone-like clothes that capture speech or monitor bodily functions.

Unlike regular optical fibers, which are made from a "preform" (a large cylinder, comprising a single material, that is heated up, stretched, then cooled), the fibers in Fink's lab are composed of several different materials, all of which must maintain their integrity through the heating and stretching process.

PIEZOELECTRIC BOOGALOO

At the core of the fibers is a plastic commonly found in microphones. Fink and company tinkered with the plastic's fluorine content to create an asymmetric distribution of fluorine molecules on one end and hydrogen molecules on the other. The imbalance is what makes the plastic "piezoelectric," which means that it changes shape when exposed to an electric field or conversely, generates electricity when under mechanical strain.
It can emit and detect sound, measure pressure and flow, and even generate electricity when stretched.

"You can actually hear them, these fibers," says Noémie Chocat, a graduate student in the materials science department. "If you connected them to a power supply and applied a sinusoidal current, then it would vibrate. And if you make it vibrate at audible frequencies and put it close to your ear, you could actually hear different notes or sounds coming out of it."

So far, the researchers have determined that the nanofiber can emit and detect sound, measure pressure and flow, and even generate electricity when stretched. Fink's team is perfecting the process to manufacture kilometers of the material at a time. Spanning large distances, the fibers can be used as loose nets that monitor the flow of water in the ocean or as sonar imaging systems with the equivalent of millions of tiny acoustic sensors.