Put your bulky boomboxes away for MIT researchers have produced ultra-thin and super light loudspeakers that can be pasted onto any rigid surface.
Most great quality loudspeakers are very heavy, and those that are lightweight and don’t take up too much space might not provide a transportive audio experience. But what if there was a way to create a powerful, high-quality sound system that is both lightweight and portable?
This is where MIT comes in. They have created paper-thin loudspeakers that can be placed on any surface and still provide excellent sound quality. The best part is that these loudspeakers are affordable, which means they can be used in various settings.
In April 2022, Massachusetts Institute of Technology (MIT) engineers released a research paper announcing that they have produced extremely thin loudspeakers, measuring only 0.12 mm in thickness. It is an ultra-thin flexible loudspeaker based on a piezoelectric micro-dome array. Unlike a regular conductor (e.g. metals), a piezoelectric material, such as quartz and ceramics, produces electricity when it is being applied mechanical pressure.
The Leader of the Organic and Nanostructured Electronics Laboratory (ONE Lab) and the senior author of the paper, Vladimir Bulović, comments, “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. It can be used anywhere. One just needs a smidgeon of electrical power to run it.”
The researchers have revealed numerous use-cases for these loudspeakers:
- Immersive entertainment: You can use these loudspeakers to cover an array of surfaces, from the inside of your car to your room. This characteristic is also what makes them fitting for immersive entertainment. Theme parks, like Disneyland, and theaters can employ them to enhance the audience’s experience.
- Future display technology: The dotted plastic sheet comprises multiple tiny domes that create patterns of light once a reflective surface is placed onto them. This could be a useful innovation for display technology, including augmented and virtual reality devices, in the future.
- Human detection: Like bats using echolocation (detecting distant objects using sound waves), the loudspeaker’s design allows users to employ ultrasound to detect the location of humans in a room. This could be useful in a variety of settings, from industrial workplaces to hospitals, as a way to detect intruders.
- Active noise cancelation: The loudspeakers generate sounds of the same amplitude as the noise source. However, they do so in such a way that the sounds cancel each other out. This is especially useful in industrial settings, like an airplane cockpit, where it is important to minimize noise.
So, how does it work?
The paper-thin loudspeakers created by MIT engineers are a new type of electrostatic loudspeaker. Compared to traditional loudspeakers, which require over one watt of power per square meter of speaker area, each of these paper-thin loudspeakers requires only 100 milliwatts of power to produce high-quality audio with minimal distortion.
What’s more, each paper-thin loudspeaker weighs only two grams—about the weight of a business card! It is made from a very thin layer of plastic with tiny holes cut into it with a laser, and this plastic layer is then laminated with a thin piezoelectric material. The piezoelectric layer will bulge through the tiny holes under the presence of electric signals, creating little domes that are only 15 microns tall each (i.e. one-sixth the thickness of human hair). The vibrations of thousands of these domes generate sounds that are audible to humans. Another layer of plastic is put on top to provide buffer space between the domes and the surface where the speakers are mounted.
Bulović notes that MIT engineers can “precisely generate mechanical motion of air by activating a physical surface that is scalable”. He exclaims, “The options of how to use this technology are limitless.” Their simple fabrication (or production) process, as defined in the research paper, makes it easy to scale this product and thus available for all.
How practical are these loudspeakers?
At a time when consumers are becoming more and more eco-conscious, seemingly random inventions like these really do give us something to think about. Anything can be environmentally sound.
These paper-thin loudspeakers might not look the most appealing, given that they are simply laminated, perforated sheets. However, they manage to produce sound using a mere fraction of the energy used by traditional loudspeakers. They also seem easy to carry, lightweight and, most importantly, do not distort audio. It is both a technical and a sustainable marvel.
While the technology is fascinating, whether it is going to take off depends on its accessibility, affordability and how it will be patented once it’s officially rolled out on the market.
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Header Image by MIT