A team at the Massachusetts Institute of Technology’s Research Lab of Electronics has discovered a method of creating fibers that can detect and produce sound. Though I’m sure you’re thinking of possible applications already (a tie that records your conversations? Pajamas that sing you to sleep?), MIT suggests such things as “clothes that are themselves sensitive microphones, for capturing speech or monitoring bodily functions, and tiny filaments that could measure blood flow in capillaries or pressure in the brain.” OK, that’s more useful and serious.
Ordinary man-made optical fibers are made of one material that is heated and drawn out, but for these acoustic fibers, MIT’s team needed specific elements to remain intact in this process. Using a certain kind of plastic and adjusting its fluorine content, they kept the pertinent molecules lined up correctly, making them piezoelectric. They also used a conducting plastic with a high graphite content, which helps the fibers keep their shape and makes them of a regular thickness. Electricity is then applied to line up the molecules correctly, and voila! Fiber that can hear and make sounds.
Noémie Chocat, a graduate student in the materials science department, says: “If you connected them to a power supply and applied a sinusoidal current” (an alternating current whose period is very regular) “then it would vibrate. And if you make it vibrate at audible frequencies and put it close to your ear, you could actually hear different notes or sounds coming out of it.”
The team is announcing the achievement with much more detail in the August issue of Nature Materials.