超薄灵活的扬声器在广泛区域部署

The thin-film loudspeaker produces sound with minimal distortion while using a fraction of the energy required by a traditional loudspeaker, say the researchers. The hand-sized loudspeaker weighs about as much as a dime and is said to be able to generate high-quality sound no matter what surface the film is bonded to.

To achieve this, the researchers say they pioneered a deceptively simple fabrication technique, which requires only three basic steps and can be scaled up to produce ultrathin loudspeakers large enough to cover the inside of an automobile or to wallpaper a room. Used this way, the thin-film loudspeaker could provide active noise cancellation in clamorous environments, such as an airplane cockpit, by generating sound of the same amplitude but opposite phase.

The flexible device could also be used for immersive entertainment, perhaps by providing three-dimensional audio in a theater or theme park ride. And because it is lightweight and requires such a small amount of power to operate, the device is well-suited for applications on smart devices where battery life is limited.

“It feels remarkable to take what looks like a slender sheet of paper, attach two clips to it, plug it into the headphone port of your computer, and start hearing sounds emanating from it,” says Vladimir Bulovic, the Fariborz Maseeh Chair in Emerging Technology, leader of the Organic and Nanostructured Electronics Laboratory (ONE Lab), director of MIT.nano, and senior author of a paper on the research. “It can be used anywhere. One just needs a smidgeon of electrical power to run it.”

While a typical loudspeaker found in headphones or an audio system uses electric current inputs that pass through a coil of wire that generates a magnetic field, which moves a speaker membrane, the new loudspeaker simplifies the speaker design by using a thin film of a shaped piezoelectric material that moves when voltage is applied over it, which moves the air above it and generates sound. Most thin-film loudspeakers are designed to be freestanding because the film must bend freely to produce sound, so mounting these loudspeakers onto a surface would impede the vibration and hamper their ability to generate sound.

To overcome this problem, the researchers say they rethought the design of a thin-film loudspeaker: Rather than having the entire material vibrate, their design relies on tiny domes on a thin layer of piezoelectric material, which each vibrate individually. These domes, each only a few hair-widths across, are surrounded by spacer layers on the top and bottom of the film that protect them from the mounting surface while still enabling them to vibrate freely. The same spacer layers protect the domes from abrasion and impact during day-to-day handling, enhancing the loudspeaker’s durability.

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