Fabric that listens through its fibers

Could the fabric of a shirt itself become a microphone? Researchers at MIT and the Rhode Island School of Design explored a textile that senses sound, rather than a separate microphone clipped to clothing. Their 2022 study used a woven piezoelectric fiber to convert sound vibrations into electrical signals.

Sound causes fabric to move, though the displacement may be only nanometers. The team took inspiration from the ear, where a vibrating membrane passes motion onward to structures that produce signals. In the fabric, the weave receives the vibration and a specialized fiber converts it into electricity.

To make that fiber, the researchers assembled materials into a larger layered preform, then heated and drew it into a thin strand. The resulting fiber could be woven together with ordinary yarn. A RISD textile researcher wove it on a conventional loom; the finished fabric remained drapable and could be washed.

Different fibers had different jobs. Relatively stiff fibers helped turn the pressure of sound waves into vibration, while the flexible piezoelectric fiber produced an electrical response. The microphone depended on the relationship between the weave and the sensing strand.

The researchers tested sounds ranging from a quiet library to traffic. In another experiment, two fabric panels sewn onto the back of a shirt helped identify the direction of a handclap. Comparing the signals reaching the two panels helped locate the sound without requiring the wearer to turn toward it.

They also tested heartbeat sounds and used the fabric to produce sound by reversing the process. These were research demonstrations, not a commercial diagnostic garment. Photographs of looms and fabric panels show the stage of development: work progressing from an individual fiber to woven fabric and then to panels attached to a garment.