Researchers at MIT have created an “acoustic fabric” that can listen to its surroundings and convert the vibrations made by sound into electrical signals, much like the human ear or a microphone. The technology consists of piezoelectric fibers that are woven into the fabric, and the resulting machine-washable material could prove useful for a variety of medtech applications, including functioning as a heart monitor, breathing monitor, and even as a component in technology designed to help the hearing impaired.
An increasing body of research involves adding new and sometimes unexpected functionalities to the everyday items we use in our lives. This latest technology is no exception – did you ever think your sweatshirt could listen to your heartbeat, or that a blanket could monitor a newborn’s breathing? Well, it’s a brave new world, because these MIT researchers have created fabrics that can “listen” and convert sounds to electrical signals that we can measure.
The fabric microphone technology is based on weaving piezoelectric fibers into common fabrics that vibrate when exposed to sound waves, resulting in an electrical signal. If present in fabric that touches the skin, the fibers can even detect the subtle noises of the heart and breathing within the chest cavity.
“Wearing an acoustic garment, you might talk through it to answer phone calls and communicate with others,” said Wei Yan, a researcher involved in the study. “In addition, this fabric can imperceptibly interface with the human skin, enabling wearers to monitor their heart and respiratory condition in a comfortable, continuous, real-time, and long-term manner.”
The MIT researchers created the fibers by starting with a “preform” that was about the size of a marker pen, and then they heated it and stretched it out into long thin fibers of up to 40 meters in length. They tested the responsivity of the resulting fibers to sound, and found that they are highly sensitive, with a performance that is comparable to that of commercial handheld microphones.
When woven into fabric, the resulting garments can detect sound highly sensitively, and can even pinpoint the direction that a particular sound is coming from, which could be useful for wearers with hearing problems.
Study in Nature: Single fibre enables acoustic fabrics via nanometre-scale vibrations