Whether you slap on whatever's handy or put together a well-coordinated ensemble, your outfit makes some sort of fashion statement. But imagine wearing clothes that could, literally, speak for themselves.

A lab at MIT has designed special fibers that can detect and emit sound. The team described exactly how they accomplished this in a paper in Nature Materials.


MIT scientists have designed smart fibers thin enough to be woven together.
Image Credit: Courtesy of Yoel Fink, MIT.

Besides having clothes that make noise, why might this be important?

Dr. Yoel Fink, a professor with MIT's department of materials science and engineering, says that highly functional fibers can be used to listen for the things your body is trying to tell you but that your ears can't seem to hear.

"Our body is about flow, the flow of blood, air and oxygen," Fink explained when I sat down with him in his office. "When flow is obstructed in any way it releases sound. It has a particular acoustic signature."

If you think about it, when doctors use a stethoscope to check your heartbeat and breathing patterns they are listening for these disruptions in flow.

However, Fink pointed out that many heart and respiratory conditions don't emerge overnight. If you were just beginning to develop a health problem, your doctor might not catch it unless it had progressed to an advanced stage.

This is where Fink's fibers come in.

If these special fibers were woven into your clothes, they could listen to your body on a daily basis and note any big changes in "flow" that occur.

When it comes to fibers, Fink certainly knows what he's talking about. His previous innovations include fibers that can take pictures and optical fibers that work as scalpels in laser surgery. This latest paper is just one step in his larger mission to make fibers that can hear, see, and sense.

These multifunctional fibers start out as foot-long rods with wires embedded inside. These rods are called preforms. To the untrained eye they look like pieces of art.

    Preforms are designed with specific geometries in mind.
    Image Credit: Courtesy of Yoel Fink, MIT.

Preforms are designed and made in the lab. Basically, metal wires are held in place and surrounded by special plastics.

The whole thing is heated up in an oven to fuse all the pieces together and remove any trapped gas.

Next, the preform is dropped into a furnace and heated to 230°C for a few hours. When it's soft enough, it's stretched out, or "drawn," into a very thin fiber. One preform rod can produce several meters of fiber, and the resulting strand is thin, around 2 mm in diameter.

At this point, the fiber can't sense or emit sound. A strong electric field needs to be applied in order to make the strand piezoelectric.

Piezoelectric materials produce mechanical force in response to an electric current and vice versa. We often use them in applications where we want to amplify sound.

For example, some acoustic guitar pickups contain piezoelectric crystals that detect mechanical vibrations produced from strumming. The crystals convert these vibrations to an electrical signal and send it along a cable to be amplified.

Fink's fibers work in a similar way.

"We can send a vibration and the fiber would detect it and generate an electric signal," said Noémie Chocat, a graduate student in Fink's lab. "[Or] we can apply an electric current to it and make it vibrate. We would hear sound generated from that vibration."

A thin piezoelectric fiber, like the one shown, emits a faint buzzing sound when a current is applied.

It's remarkable. When Chocat hooked a finished fiber up to a circuit and held it to my ear, I could hear a faint buzzing noise.

    Functional fibers could be woven into fabrics some day very soon.
    Image Credit: Courtesy of Yoel Fink, MIT.

Of course, we won't be able to run out today and buy shirts rigged up to monitor our heartbeats or broadcast messages. Still, it's amazing to think of what capabilities our clothes will have in the future.

Fink believes that the arrival of highly functional fabrics is long overdue.

"People have always been excited about fabrics and clothes that could do things for you, that could heat or cool or change their color," Fink said. "I think there's a lot here."

Intern Rebecca Cheung is a graduate student at the University of British Columbia's School of Journalism.

User Comments:

Any other application for this application, besides guitars?

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