Researchers at MIT have developed a new type of paper-thin speaker that is light and strong enough to be attached to any surface. And, as it turned out, it is not as expensive to produce as it may seem at first glance.
MIT says that a paper speaker can be created using a three-step process that is simpler than making traditional speakers.
Of course, thin speakers is not something brand-new – planar magnetic and electrostatic drivers are also based on thin and flat vibrating material, which gave us extremely thin speaker designs.
The material used by MIT experts is not unusual – it is a polyvinylidene fluoride film (PVDF), which has piezoelectric properties and has been used for speakers since at least the 1970s. Traditionally, PVDF speakers have faced a number of design problems that have hampered their commercial viability, including mediocre durability and limited frequency response. They also required a strong load-bearing structure and, in the end, did not offer much advantage over traditional drivers.
The main innovation from MIT, apparently, is to strengthen the material by changing its shape. The perforated layer of PET plastic is applied to a sheet of PVDF, which during heat treatment in vacuum causes PVDF to be forced through the perforation, creating many tiny domes. It’s like a very small bubble film that can produce more than just a clapping sound. Instead of just vibrating the entire sheet of PVDF material in unison, only the “domes” vibrate. Meanwhile, the PET layers surrounding the domes provide the necessary structural integrity so that the material can bend and attach to surfaces without interfering with sound reproduction.
Manufacturers can then adjust the acoustic properties of the material by resizing and rearranging the domes, leading to a variety of interesting applications. Domes can be designed to focus sound in certain places in the room, and be used in ultrasound imaging.
And as a result we have a very thin and flexible material that can act as wallpaper in the house. In addition to the immersion effect, theoretically with the help of this wallpaper you can turn your walls into noise-suppressing surfaces that will work just like noise-canceling headphones, i.e. prevent the penetration of external noises into your home.