You may be resigned to wearing a pair of headphones all day to block out sounds from loud 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 of 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, the membrane moves back and forth and pushes 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 some power and space to operate. Just look at the huge tower of speakers on either side of the stage at a concert and you’ll see why there’s room for improvement when it comes to speaker technology.
Researchers at MIT’s Organic and Nanostructured Electronics Laboratory have created a new kind of thin-film speaker that’s as thin and flexible as a sheet of paper, but can also deliver clear, high-quality sound, even when it is glued to a rigid surface such as a wall. This isn’t the first time researchers have created ultra-thin and lightweight speakers, but previous attempts have resulted in a film that must be self-contained and unfettered to produce sound. When mounted on a rigid surface, the ability of thinner speakers to vibrate and move air is greatly reduced, limiting where and how they can be used. But MIT researchers have now developed a new manufacturing process that solves this 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 punched 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 the two layers to a vacuum and 80-degree heat, causing the piezoelectric layer to swell and push to through the laser cut holes. in the top layer. This created a series of tiny domes that can pulsate and vibrate when an electric current is applied, whether or not the panel is attached to a rigid surface. The researchers also added a few extra layers of durable PET plastic to create a spacer to allow the domes to vibrate freely and protect them from abrasion damage.
The domes are only “one-sixth the thickness of a human hair” in height and move only half a micron up and down when vibrating. Se necesitan miles para producir sonidos audibles, pero los investigators también decubrieron que cambiar el tamaño de los agujeros cortados con laser, que también altera el tamaño de las cúpulas producidas, pero que el sonido producido por el panel delgado film se sintonice par que sea stronger. Debido a que las cúpulas tienen a movimiento tan diminuto, solo 100 milivatios de electricidad necesitaron para alimentar a solo metro cuadrado del material, en comparación con más de un vatio completo de electricidad necesario para alimentar une altavoz estándar para crear une nivel comparable de presión sound.
The applications for thin-film loudspeaker materials are endless. Besides being applied indoors like the walls of an office or even inside an airplane to cancel out unwanted noise, an entire car can be wrapped in a speaker, allowing easily alert pedestrians that you are approaching. a quiet electric vehicle. Researchers believe the technology could even be used for ultrasound 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 Texas Instrument DLP technology. But the one thing researchers can’t predict is when we’ll see this technology hit the market.