MIT creates a thin speaker

Researchers at MIT (Massachusetts Institute of Technology), one of the world’s most prestigious science and technology laboratories, have announced an invention that can turn any surface into a loudspeaker: a paper-thick speaker.

The device is not only thin: its weight is comparable to a coin, the sound quality (according to the inventors) is high and the level of power consumption is low. This ultra-thin speaker can be used for car interior upholstery or as a backdrop in the home.

says Vladimir Polovich, director of the Nanotechnology Laboratory at MIT and author of the scientific paper describing the invention, which was published this week in the journal IEEE Transactions of Industrial Electronics.

In the video below, you see a demonstration of the technology: an ultra-thin speaker playing “We Are The Champions” by British band Queen.

To understand how an ultra-thin speaker works, we first need to understand how the models we use today in headphones, computers, cell phones, televisions, and speakers — a design that has worked well for over 150 years but needed a lot of power and space to work.

An ordinary speaker is made of a coil of wire that, when it receives an electric current, generates a magnetic field. This magnetic field moves a membrane which in turn moves air over it at a rate and speed that our ears perceive as sound.

MIT’s new loudspeaker hits the road: Instead of using a coil of wire to conduct electrical current to the membrane, the invention uses a piezoelectric material called PVDF (a type of plastic) that vibrates when it receives an electric charge, itself generating the sound we hear.

So far, nothing new: Scientists have used this technology before to create ultra-thin speakers. The problem is that prototypes made in the past were very sensitive – any touch or pressure could stop the vibration and silence them.

MIT Disclosure / MIT Disclosure / MIT

Microscopic bubbles vibrate and make the paper make a sound

Photo: Disclosure / MIT

What’s new is that MIT has found a way to make it more stable: Instead of making the entire material vibrate, the researchers used a sheet of lightweight PET plastic with small laser-cut holes. A layer of PVDF was then laminated to the underside of the plate and then both layers were vacuum sealed and exposed to a temperature of 80 °C.

The heat caused the PVDF layer to protrude through the holes, creating tiny bubbles smaller than the thickness of a human hair. Thousands of these microscopic bubbles vibrate and move air when they receive an electric current, producing sound regardless of contact or pressure.

Because the vibrations are so small (each bubble rises and falls in an area of ​​less than 1 micrometer), only 100 milliwatts of electricity is enough to power one square meter of the speaker. For comparison, today’s average amplifier needs at least 1 watt to produce similar sound.

“It’s amazing to be able to take what appears to be a thin piece of paper, attach two paper clips to it, plug it into your computer’s headphone port, and start hearing the sounds from it,” Polovich says in the ad. MIT website.

Says Jinshi Han, a postdoctoral fellow at MIT who collaborated on the research, pointing to the process for mass manufacturing of flexible electronics.

“This means that [este alto-falante] They can be manufactured in large quantities as wallpaper to cover walls, cars or the interior of aircraft,” adds the researcher.

In addition to listening to music, MIT’s ultra-thin loudspeaker can also be used as a noise-cancelling system, emitting an audio frequency that mirrors the sound outside of an airplane, for example, making flights less annoying.

The researchers don’t know when the technology will come to market, but part of the study was funded by the automaker Ford, which may be interested in covering its cars with the ultra-thin subwoofer in the future. “The options for how to use this technology are endless,” Polovich says.

Leave a Comment