This new fabric can “hear” sounds or broadcast them

Someday our clothes can eavesdrop on the soundtrack of our lives.

The new fiber acts as a microphone. He can catch speech, rustle leaves – even chirp birds. Then it turns out those acoustic signals in electric. These fibers are woven into the fabric hear clapping and faint sounds. They may even catch its owner’s heartbeat, researchers said on March 16 Nature.

Fabrics containing these fibers can be an easy, comfortable, and perhaps fashionable way to listen to our organs or improve hearing.

The fabric that interacts with sounds has existed for perhaps hundreds of years, Wei Yang says. He worked on fabric at the Massachusetts Institute of Technology, or Massachusetts Institute of Technology, in Cambridge. As a materials scientist, he uses physics and chemistry to research and design materials.

Fabrics were commonly used to muffle sound, says Yang, who now works at Nanyang Technological University in Singapore. Using fabric as a microphone, he says, is “a completely different concept”.

Taking a punch from the eardrum

The new study was inspired by the human eardrum, says Ian. Sound waves cause the eardrum to vibrate. The auricle (KOAK-lee-uh) converts these vibrations into electrical signals. “It turns out that this eardrum is made of fibers,” says materialist Joel Fink. He was part of the MIT team that developed the new fabric.

The fibers in the inner layers of the eardrum intersect. Some come from the center of the eardrum. Others form circles. Made of protein collagen, these fibers help people hear. Their location, Fink says, is reminiscent of fabrics woven by humans.

Just like it does with the eardrum, the sound vibrates the fabric. The new fabric contains cotton fibers and others made from a tough material called Twaron. This combination of threads helps convert the energy of sounds into vibrations. But the fabric also includes a special fiber. It contains a mixture of piezoelectric materials. Such materials are produced by Fr. tension when pressed or bent. The tiny buckles and bends of the piezoelectric fiber create electrical signals. These signals can be sent to a device that reads and writes voltage.

The fabric microphone works at different sound levels. He feels the difference between a quiet library and heavy traffic, the team said. Researchers are still working on using computer software to help distinguish the sounds they want to hear from noise. When woven into clothing, the sound-sensitive fabric feels like normal, Ian says. In tests, it continued to work as a microphone even after 10 washes.

Piezoelectric materials have “enormous potential” for application, says Vijay Thakur. A materialist, he works at the Rural College of Scotland in Edinburgh and was not involved in the development of the new fabric.

People researched piezoelectric materials to produce energy from vibrations. But these materials were limited by the very small stresses they produce. The method of producing new special fibers overcomes this problem, he says. Their outer layer is very elastic and flexible. It doesn’t take much energy to bend them. It concentrates the vibration energy in the piezoelectric layer. This makes the microphone more sensitive, says Thakur, who was not involved in the study.

High-tech threads

As proof of concept, the team wove a fabric mic into his shirt. Like a stethoscope, he could hear his owner’s heartbeat. “It’s really inspiring,” says Yogendra Mishra, who was also not involved in the new work. A materials engineer, he works at the University of Southern Denmark in Sonderborg. With the fiber installed near the heart, this shirt could reliably measure someone’s heart rate.

The authors report that he may also hear audible signals of closing some heart valves. In this way, the tissue microphone can listen for noise. These are unusual sounds that may indicate that something is wrong with the heart.

Thakur says someday tissue can provide information like an echocardiogram (Ek-oh-kar-dee-oh-gram). Such sensors are used sound waves in the image heart. If they are shown to work to control the body and to diagnose diseases, listening fabrics can find application in young children’s clothing. Such clothing can make it easier to track heart condition in toddlers who can’t stay still, he says.

The team also believes that a tissue microphone can help people who have hearing problems. This can both amplify the sound and help people determine the direction of the sound. To test this, Ian and his colleagues made a shirt with two sound-sensitive fibers on the back. These fibers could determine the direction from which the splash came. Since the two fibers were spaced apart, there was little difference in whether each caught sound.

And when connected to a power source, the fabric of the new fibers can even transmit sound, acting as a speaker. Voltage signals sent to the fabric cause vibrations that emit audible sounds.

“For the past 20 years, we’ve been trying to introduce a new way of thinking about fabrics,” says Fink of the Massachusetts Institute of Technology. Fabrics have long provided beauty and warmth, but they can do more. They can help solve some acoustic problems. And maybe, Fink says, they can also embellish technology.

It is one in a series of news stories about technology and innovation that have been made possible with the generous support of the Lemelson Foundation.