MIT's thin plastic speakers fall flat. And that's by design

The walls are alive with the sound of music


Video Engineers at MIT have created paper-thin speakers using a plastic film and a piezoelectric layer embossed with tiny domes.

These sheet speakers could potentially be applied to any surface for sound output or input: think surround sound or noise cancellation in aircraft. The technology also has potential for ultrasound imaging and echolocation, among other possibilities.

The work is described in a paper published recently in the journal IEEE Transactions on Industrial Electronics, "An Ultra-Thin Flexible Loudspeaker Based on a Piezoelectric Micro-Dome Array."

"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," Vladimir Bulović, leader of the Organic and Nanostructured Electronics Laboratory (ONE Lab), director of MIT.nano, and senior author of the paper, told the MIT News Office.

The other two co-authors of the paper are Jinchi Han, a ONE Lab postdoc, and Jeffrey Lang, professor of electrical engineering at MIT.

The boffins have produced a short YouTube video that demonstrates the technology:

Youtube Video

Traditional speakers translate electrical signals into a magnetic field that moves a speaker membrane to create audible vibrations. The MIT academics got rid of the coiled wire that generates the membrane-moving magnetic field by using piezoelectric material – which converts electrical energy to mechanical energy (and vice versa) – to move a microarray of domes that generate sound.

Their design relies on a sheet of plastic known as PET (polyethylene terephthalate) that's perforated and layered with a thin film of piezoelectric material, called PVDF (polyvinylidene fluoride).

When these sheets are heat bonded to create a vacuum, the result is a flat array of tiny domes that move when voltage is applied. The design creates enough separation of materials to allow the domes to vibrate without interference when the plastic film has been mounted to a surface.

At a distance of 30cm (12 inches), it's claimed, these thin-film speakers can generate high-quality sound equivalent to the volume of a typical conversation (66 decibels) through the application of 25 volts of electricity at 1 kilohertz. At 10 kilohertz, sound output reached the level of city traffic (86 decibels).

The sheet-speakers supposedly require only 100 milliwatts of power per square meter of speaker area, significantly less than home speakers that use more than 1 watt of power for comparable sound pressure at the same distance.

Jinchi Han told The Register in an email that the speakers have been tested between 100 Hz to 100 kHz.

"They are able to produce sound at low frequencies, but sensitivities (acoustic pressure generated under unit voltage) are usually higher at high frequencies than those at low frequencies," said Han.

According to the MIT News Office, the technology is simple to fabricate and can be scaled up to cover the interior of a room or vehicle – the research was funded in part by Ford Motor Company. This would allow covered surfaces to emit sound for listening or for noise cancellation.

Ioannis (John) Kymissis, professor of electrical engineering and Chair of the department of electrical engineering at Columbia University, told the MIT News Office that the technology could also be used to record sound – the domes, acting as tiny microphones, would capture vibrations.

MIT professor Jeffrey Lang confirmed as much in an email to The Register.

"The same device can work as a microphone," said Lang. "It can be mounted on the surface of any object and used for sound recording. The device itself is passive and generates voltage signal under incident acoustic waves. But we apply a small transimpedance amplifier in order to obtain a large signal-to-noise ratio."

"We actually have an upcoming paper that reports the microphonic performance of the same device. The amplifier is the only part that consumes power. If a standalone design is needed, usually the signal storage/processing and wireless transmission consume much more power than the amplifier itself."

"But we can either use a battery or integrate energy harvesting components to make it standalone without wiring to external power. For instance, our group is also developing thin-film solar cells and it's possible to integrate that with the acoustic thin film to provide the energy."

Han said the technology has potential for ultrasound applications because it can generate the high resonance frequency necessary for ultrasound imaging. Echolocation is another possible application, according to Bulović, who also suggested the micro-speaker array combined with a reflective surface could be used as a display technology by creating patterns of light. ®

Similar topics


Other stories you might like

  • Quantum internet within grasp as scientists show off entanglement demo
    Teleportation of quantum information key to future secure data transfer

    Researchers in the Netherlands have shown they can transmit quantum information via an intermediary node, a feature necessary to make the so-called quantum internet possible.

    In recent years, scientists have argued that the quantum internet presents a more desirable network for transferring secure data, in addition to being necessary when connecting multiple quantum systems. All of this has been attracting investment from the US government, among others.

    Despite the promise, there are still vital elements missing for the creation of a functional quantum internet.

    Continue reading
  • Drone ship carrying yet more drones launches in China
    Zhuhai Cloud will carry 50 flying and diving machines it can control with minimal human assistance

    Chinese academics have christened an ocean research vessel that has a twist: it will sail the seas with a complement of aerial and ocean-going drones and no human crew.

    The Zhu Hai Yun, or Zhuhai Cloud, launched in Guangzhou after a year of construction. The 290-foot-long mothership can hit a top speed of 18 knots (about 20 miles per hour) and will carry 50 flying, surface, and submersible drones that launch and self-recover autonomously. 

    According to this blurb from the shipbuilder behind its construction, the Cloud will also be equipped with a variety of additional observational instruments "which can be deployed in batches in the target sea area, and carry out task-oriented adaptive networking to achieve three-dimensional view of specific targets." Most of the ship is an open deck where flying drones can land and be stored. The ship is also equipped with launch and recovery equipment for its aquatic craft. 

    Continue reading
  • Experts: AI should be recognized as inventors in patent law
    Plus: Police release deepfake of murdered teen in cold case, and more

    In-brief Governments around the world should pass intellectual property laws that grant rights to AI systems, two academics at the University of New South Wales in Australia argued.

    Alexandra George, and Toby Walsh, professors of law and AI, respectively, believe failing to recognize machines as inventors could have long-lasting impacts on economies and societies. 

    "If courts and governments decide that AI-made inventions cannot be patented, the implications could be huge," they wrote in a comment article published in Nature. "Funders and businesses would be less incentivized to pursue useful research using AI inventors when a return on their investment could be limited. Society could miss out on the development of worthwhile and life-saving inventions."

    Continue reading
  • SEC probes Musk for not properly disclosing Twitter stake
    Meanwhile, social network's board rejects resignation of one its directors

    America's financial watchdog is investigating whether Elon Musk adequately disclosed his purchase of Twitter shares last month, just as his bid to take over the social media company hangs in the balance. 

    A letter [PDF] from the SEC addressed to the tech billionaire said he "[did] not appear" to have filed the proper form detailing his 9.2 percent stake in Twitter "required 10 days from the date of acquisition," and asked him to provide more information. Musk's shares made him one of Twitter's largest shareholders. The letter is dated April 4, and was shared this week by the regulator.

    Musk quickly moved to try and buy the whole company outright in a deal initially worth over $44 billion. Musk sold a chunk of his shares in Tesla worth $8.4 billion and bagged another $7.14 billion from investors to help finance the $21 billion he promised to put forward for the deal. The remaining $25.5 billion bill was secured via debt financing by Morgan Stanley, Bank of America, Barclays, and others. But the takeover is not going smoothly.

    Continue reading
  • Cloud security unicorn cuts 20% of staff after raising $1.3b
    Time to play blame bingo: Markets? Profits? Too much growth? Russia? Space aliens?

    Cloud security company Lacework has laid off 20 percent of its employees, just months after two record-breaking funding rounds pushed its valuation to $8.3 billion.

    A spokesperson wouldn't confirm the total number of employees affected, though told The Register that the "widely speculated number on Twitter is a significant overestimate."

    The company, as of March, counted more than 1,000 employees, which would push the jobs lost above 200. And the widely reported number on Twitter is about 300 employees. The biz, based in Silicon Valley, was founded in 2015.

    Continue reading
  • Talos names eight deadly sins in widely used industrial software
    Entire swaths of gear relies on vulnerability-laden Open Automation Software (OAS)

    A researcher at Cisco's Talos threat intelligence team found eight vulnerabilities in the Open Automation Software (OAS) platform that, if exploited, could enable a bad actor to access a device and run code on a targeted system.

    The OAS platform is widely used by a range of industrial enterprises, essentially facilitating the transfer of data within an IT environment between hardware and software and playing a central role in organizations' industrial Internet of Things (IIoT) efforts. It touches a range of devices, including PLCs and OPCs and IoT devices, as well as custom applications and APIs, databases and edge systems.

    Companies like Volvo, General Dynamics, JBT Aerotech and wind-turbine maker AES are among the users of the OAS platform.

    Continue reading
  • Despite global uncertainty, $500m hit doesn't rattle Nvidia execs
    CEO acknowledges impact of war, pandemic but says fundamentals ‘are really good’

    Nvidia is expecting a $500 million hit to its global datacenter and consumer business in the second quarter due to COVID lockdowns in China and Russia's invasion of Ukraine. Despite those and other macroeconomic concerns, executives are still optimistic about future prospects.

    "The full impact and duration of the war in Ukraine and COVID lockdowns in China is difficult to predict. However, the impact of our technology and our market opportunities remain unchanged," said Jensen Huang, Nvidia's CEO and co-founder, during the company's first-quarter earnings call.

    Those two statements might sound a little contradictory, including to some investors, particularly following the stock selloff yesterday after concerns over Russia and China prompted Nvidia to issue lower-than-expected guidance for second-quarter revenue.

    Continue reading
  • Another AI supercomputer from HPE: Champollion lands in France
    That's the second in a week following similar system in Munich also aimed at researchers

    HPE is lifting the lid on a new AI supercomputer – the second this week – aimed at building and training larger machine learning models to underpin research.

    Based at HPE's Center of Excellence in Grenoble, France, the new supercomputer is to be named Champollion after the French scholar who made advances in deciphering Egyptian hieroglyphs in the 19th century. It was built in partnership with Nvidia using AMD-based Apollo computer nodes fitted with Nvidia's A100 GPUs.

    Champollion brings together HPC and purpose-built AI technologies to train machine learning models at scale and unlock results faster, HPE said. HPE already provides HPC and AI resources from its Grenoble facilities for customers, and the broader research community to access, and said it plans to provide access to Champollion for scientists and engineers globally to accelerate testing of their AI models and research.

    Continue reading

Biting the hand that feeds IT © 1998–2022