You may be resigned to wearing a pair of headphones all day to block out sounds from noisy neighbors or other distractions, but MIT researchers have developed a loudspeaker as thin as paper that can be applied to almost any surface, such as wallpaper, and turn objects like walls into giant noise-canceling speakers.
Take apart the speakers in almost any consumer device that produces sound and you’ll find essentially the same hardware: a membrane combined with a coil of wire that produces a magnetic field (or other moving mechanism). When electricity is applied, this causes the membrane to move back and forth and push the air in specific patterns, creating sound waves that reach our ears. It’s a simple formula that has worked well for over 150 years, but requires a certain amount of power and a certain amount of space to run. Just look at the massive speaker tower on either side of the stage at a concert and you’ll understand why there’s room for some improvement when it comes to speaker technology.
Researchers at MIT’s Laboratory for Organic and Nanostructured Electronics have created a new type of thin-film speaker that is as thin and flexible as a sheet of paper, but can also generate clear, high-quality sound, even when adhered to a rigid surface such as a wall. This isn’t the first time researchers have created ultra-thin, lightweight speakers, but previous attempts have resulted in a film that needs to be self-contained and unfettered to produce sound. When mounted on a rigid surface, thinner speakers’ ability to vibrate and move air is greatly reduced, limiting where and how they can be used. But MIT researchers have now come up with a new manufacturing process that solves that problem.
Instead of designing a thin-film speaker that requires the entire panel to vibrate, the researchers started with a sheet of lightweight PET plastic that they drilled tiny holes with a laser. Next, a layer of thin piezoelectric material called PVDF was laminated to the bottom of the sheet, and the researchers then subjected both layers to a vacuum and 80-degree heat, causing the piezoelectric layer to bulge and push through. from the laser cut holes in the top layer. This created a series of tiny domes that can pulsate and vibrate when an electrical current is applied, regardless of whether or not the panel is attached to a rigid surface. The researchers also added a few extra layers of the durable PET plastic to create a spacer to ensure the domes can vibrate freely and to protect them from abrasion damage.
The domes are only “one-sixth the thickness of a human hair” in height and move just half a micron up and down when they vibrate. Thousands are needed to produce audible sounds, but the researchers also found that changing the size of the laser-cut holes, which also alters the size of the domes produced, allows the sound produced by the thin-film panel to be tuned to be stronger. Because the domes have such minute movement, it only took 100 milliwatts of electricity to power a single square meter of the material, compared to more than a full watt of electricity needed to power a standard loudspeaker to create a comparable level of pressure. Sound.
The applications for thin film loudspeaker material are endless. As well as being applied indoors like office walls or even inside an airplane to cancel out unwanted noise, an entire car might be wrapped in a speaker, making it easy to alert pedestrians that you are approaching. a silent electric vehicle. The researchers think the technology might even be used for ultrasonic imaging, tracking people’s movements in a given space, or even as a futuristic display technology by covering all those little domes with reflective surfaces, similar to how the technology works. Texas Instrument DLP. But the one thing the researchers can’t predict is when we might see this technology on the market.
