Researchers at MIT have created an “acoustic tissue” capable of listening to its environment and converting the vibrations emitted 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 medical technology applications, including as a heart monitor, respiratory monitor and even as a as part of a technology designed to help the hearing impaired.
A growing body of research involves adding new and sometimes unexpected functionality to the everyday objects we use in our lives. This latest technology is no exception. Have you ever thought that your sweatshirt could listen to your heartbeat or that a blanket could monitor a newborn baby’s breathing? Well, it’s a brave new world, because these MIT researchers have created tissues that can “listen” and convert sounds into electrical signals that we can measure.
Cloth microphone technology is based on weaving piezoelectric fibers into common fabrics that vibrate when exposed to sound waves, producing an electrical signal. If present in tissue that touches the skin, the fibers can even detect subtle heart and breath sounds in the chest cavity.
“By wearing an acoustic garment, you could talk through to answer phone calls and communicate with others,” said Wei Yan, a researcher involved in the study. “Additionally, this fabric can interface imperceptibly with human skin, allowing wearers to comfortably monitor their cardiac and respiratory status in a 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, then heating and stretching it into long, thin fibers that could be up to 40 meters long. They tested the resulting fibers for responsiveness to sound and found them to be highly responsive, with performance comparable to commercial handheld microphones.
When woven into the fabric, the resulting garments can detect sound very sensitively and can even identify the direction a particular sound is coming from, which could be useful for wearers with hearing problems. .
Study in Nature: Single fiber enables acoustic fabrics via nanoscale vibrations