Fiber material

This fiber can turn your clothes into listening devices

Imagine if you could wear one ear. It probably sounds like the plot of a gruesome 70s sci-fi script. But be patient, this is actually the future of fabric, and it could very well play a new role in some critical medical applications.

In a new study published Wednesday in the journal Nature, researchers across the United States have created a fiber that can bend at the slightest sound. When woven into a shirt, the fibers were able to pick up the direction a sound was coming from, even sounds as faint as the heartbeat of a living person.

“The project looks very exciting,” Swarun Kumar, an electrical engineer at Carnegie Mellon University who was not part of the study, told The Daily Beast in an email. “The health implications of this work, such as detecting beats and heart rhythms, seem very [promising].”

The fibers when woven into a fabric.

Yoel Fink

These “intelligent fabrics” capable of detecting and responding to external stimuli (such as sound, heat or light) have their origins in research in Japan in the late 1980s, when scientists designed a silk thread with shape memory. In recent years, we’ve seen the emergence of smart fabrics woven with near-field communication antennas, the technology used to pair devices and make contactless payments. Some are even able to boast that they can fold up on their own.

“A key aspect of smart fabrics is that the flexibility makes them easier to integrate into a human environment,” Julie Chen, a mechanical engineer at University of Massachusetts Lowell who was not part of the study, told The Daily. Beast in an email. “Not just because they’re ‘portable’, but because they can conform to complex 3D shapes, rather than being rigid slabs or boxes.”

Yoel Fink, an electrical engineer at MIT, and his colleagues were encouraged to take smart fabrics one step further and see if it was possible to make these fibers react to sound.

The researchers realized they could simply copy Mother Nature: in the human ear, the vibrational energy of sound oscillates hair fibers deep in the ear, generating electrical impulses which are then transmitted to the brain to allow us to treat these vibrations as ringing.

This led Fink and his team to create a new fiber that was strong enough yet flexible and generated an electrical signal when bent – the perfect cloth ear. By testing the sensitivity of a single fiber, they found that it could pick up the most imperceptible sounds in a quiet library as easily as the noises of heavy road traffic or a speaker playing nearby. The sensitivity was so precise that if someone wore a shirt woven with the fibers, they could tell which direction a sound was coming from.

The fibers start as a block of layered material, called a preform, which is then heated and hammered into a yarn.

Yoel Fink

“When you put multiple fibers into a fabric, they can actually tell you the direction, and you can tune them to listen for particular directions and with quite astonishing accuracy,” Fink, co-author of the new study, told The Daily. beast.

Researchers see endless possibilities for their smart fabric. The obvious application is in improving hearing aids, which Fink says have trouble discerning the direction of a sound, especially in noisy environments. But the fabric could also help engineers design wearable fabrics that can measure vital signs, monitor space dust in new types of spacecraft, and listen for signs of building deterioration such as cracks and warping. emerging.

“An OB/GYN [doctor] told me that we didn’t have effective ways to monitor the fetal heart outside of the hospital,” Fink said, adding that his team was able to accurately detect certain heart sounds when they sewed a fiber just above the heart in a healthy shirt. volunteer. “We will be working on using our fiber for fetal heart monitoring for sure.”

They also want their fibers to act as a boombox or sound cancellation system, which they did in the lab by reversing electrical signals into vibrations.

Although the fibers are very sensitive to vibrations, they cannot really tell what an incoming sound is, especially if there are several at the same time. For this, Fink and his team plan to do research using algorithms and machine learning to identify the electrical signal of a sound in order to make sense of it for the future user.

“Fibers are ubiquitous – there are very few materials as intimate as fibers and fabric,” Fink said. “They’ve been around us from the moment we were born, so wouldn’t it be great if they could not only keep us warm and comfortable, but really add value to things?”