Tag Archives: loudspeakers

Printing paper loudspeakers

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When I was working on my undergraduate communications degree, we spent a fair chunk of time discussing the printed word; this introduction (below in the excerpt) brings back memories. I am going to start with an excerpt from the study (link and citation to follow at the end of this post) before moving on to the news item and press release. It’s a good introduction (Note Links have been removed),

For a long time, paper has been used as storing medium for written information only [emphasis mine]. In combination with the development of printing technologies, it became one of the most relevant materials as information could be reproduced multiple times and brought to millions of people in a simple, cheap, and fast way. However, with the digital revolution the end of paper has been forecasted.

However, paper still has its big advantages. The yearly production is still huge with over 400 million tons worldwide[1] for a wide application range going much beyond conventional books, newspapers, packages, or sanitary products. It is a natural light‐weight, flexible, recyclable, multi‐functional material making it an ideal candidate as part of novel electronic devices, especially based on printed electronics.[2] During the last decade, a wide variety of electronic functionalities have been demonstrated with paper as the common substrate platform. It has been used as basis for organic circuits,[3] microwave and digital electronics,[4] sensors,[5-7] actuators,[8, 9] and many more.

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My first posting about this work from Chemnitz University of Technology with paper, loudspeakers, and printed electronics was a May 4, 2012 posting.

Enough of that trip down memory lane, a January 26, 2021 news item on Nanowerk announces research into printing loudspeakers onto roll-to-roll printed paper,

If the Institute for Print and Media Technology at Chemnitz University of Technology [Germany] has its way, many loudspeakers of the future will not only be as thin as paper, but will also sound impressive. This is a reality in the laboratories of the Chemnitz researchers, who back in 2015 developed the multiple award-winning T-Book – a large-format illustrated book equipped with printed electronics. If you turn a page, it begins to sound through a speaker invisibly located inside the sheet of paper.

“The T-Book was and is a milestone in the development of printed electronics, but development is continuing all the time,” says Prof. Dr. Arved C. Hübler, under whose leadership this technology trend, which is becoming increasingly important worldwide, has been driven forward for more than 20 years.

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A January 26, 2021 Chemnitz University of Technology press release by Mario Steinebach/Translator: Chelsea Burris, which originated the news item, delves further into the topic,

From single-sheet production to roll-to-roll printing

Five years ago, the sonorous paper loudspeakers from Chemnitz were still manufactured in a semi-automatic single-sheet production process. In this process, ordinary paper or foils are printed with two layers of a conductive organic polymer as electrodes. A piezoelectric layer is sandwiched between them as the active element, which causes the paper or film to vibrate. Loud and clear sound is produced by air displacement. The two sides of the speaker paper can be printed in color. Since this was only possible in individual sheets in limited formats, the efficiency of this relatively slow manufacturing process is very low. That’s why researchers at the Institute of Print and Media Technology have been looking for a new way towards cost-effective mass production since May 2017.

The aim of their latest project, roll-to-roll printed speaker paper (T-Paper for short), was therefore to convert sheet production into roll production. “Researchers from the fields of print media technology, chemistry, physics, acoustics, electrical engineering, and economics from six nations developed a continuous, highly productive, and reliable roll production of loudspeaker webs,” reports project manager Georg C. Schmidt. Not only did they use the roll-to-roll (R2R) printing process for this, but they also developed inline technologies for other process steps, such as the lamination of functional layers. “This allows electronics to be embedded in the paper – invisibly and protected,” says Hübler. In addition, he says, inline polarization of piezoelectric polymer layers has been achieved for the first time and complete inline process monitoring of the printed functional layers is possible. The final project results were published in the renowned journal Advanced Materials in January 2021.

Long and lightweight paper loudspeaker webs for museums, the advertising industry, and Industry 4.0

The potential of loudspeaker paper was extended to other areas of application in the T-Paper project. For example, meter-long loudspeaker installations can now be manufactured in web form or as a circle (T-RING). “In our T-RING prototype, an almost four-meter-long track with 56 individual loudspeakers was connected to form seven segments and shaped into a circle, making a 360° surround sound installation possible,” says Schmidt. The speaker track, including printed circuitry, weighs just 150 grams and consists of 90 percent conventional paper that can be printed in color on both sides. “This means that low-cost infotainment solutions are now possible in museums, at trade shows and in the advertising industry, for example. In public buildings, for example, very homogeneous sound reinforcement of long stretches such as corridors is possible. But the process technology itself could also become interesting for other areas, such as the production of inline measurement systems for Industry 4.0,” says the project manager, looking to the future.

The T-Paper project was funded by the Federal Ministry of Education and Research from 2017 to 2020 with 1.37 million euros as part of the Validation of the technological and societal innovation potential of scientific research – VIP+ funding measure.

Here’s a link to and a citation for the paper,

Paper‐Embedded Roll‐to‐Roll Mass Printed Piezoelectric Transducers by Georg C. Schmidt, Pramul M. Panicker, Xunlin Qiu, Aravindan J. Benjamin, Ricardo A. Quintana Soler, Issac Wils, Arved C. Hübler. Advanced Materials DOI: https://doi.org/10.1002/adma.202006437 First published: 18 January 2021

This paper is open access.

For anyone curious about the T-Paper project, you can find it here.

“Ears like a bat” could come true for humans?

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That old saying which describes people with exceptional hearing as having “ears like a bat” may come true if University of California at Berkeley (UC Berkeley) researchers have their way. From a July 7, 2015 news item on Nanowerk,

University of California, Berkeley, physicists have used graphene to build lightweight ultrasonic loudspeakers and microphones, enabling people to mimic bats or dolphins’ ability to use sound to communicate and gauge the distance and speed of objects around them.

A July 6, 2015 UC Berkeley news release by Robert Sanders (also on EurekAlert), which originated the news item, describes the problem addressed by the research and the new approach taken,

More practically, the wireless ultrasound devices complement standard radio transmission using electromagnetic waves in areas where radio is impractical, such as underwater, but with far more fidelity than current ultrasound or sonar devices. They can also be used to communicate through objects, such as steel, that electromagnetic waves can’t penetrate.

“Sea mammals and bats use high-frequency sound for echolocation and communication, but humans just haven’t fully exploited that before, in my opinion, because the technology has not been there,” said UC Berkeley physicist Alex Zettl. “Until now, we have not had good wideband ultrasound transmitters or receivers. These new devices are a technology opportunity.”

Speakers and microphones both use diaphragms, typically made of paper or plastic, that vibrate to produce or detect sound, respectively. The diaphragms in the new devices are graphene sheets a mere one atom thick that have the right combination of stiffness, strength and light weight to respond to frequencies ranging from subsonic (below 20 hertz) to ultrasonic (above 20 kilohertz). Humans can hear from 20 hertz up to 20,000 hertz, whereas bats hear only in the kilohertz range, from 9 to 200 kilohertz. The grapheme loudspeakers and microphones operate from well below 20 hertz to over 500 kilohertz.

Graphene consists of carbon atoms laid out in a hexagonal, chicken-wire arrangement, which creates a tough, lightweight sheet with unique electronic properties that have excited the physics world for the past 20 or more years.

“There’s a lot of talk about using graphene in electronics and small nanoscale devices, but they’re all a ways away,” said Zettl, who is a senior scientist at Lawrence Berkeley National Laboratory and a member of the Kavli Energy NanoSciences Institute, operated jointly by UC Berkeley and Berkeley Lab. “The microphone and loudspeaker are some of the closest devices to commercial viability, because we’ve worked out how to make the graphene and mount it, and it’s easy to scale up.”

Zettl, UC Berkeley postdoctoral fellow Qin Zhou and colleagues describe their graphene microphone and ultrasonic radio in a paper appearing online this week in the Proceedings of the National Academy of Sciences.

Radios and rangefinders

Two years ago, Zhou built loudspeakers using a sheet of graphene for the diaphragm, and since then has been developing the electronic circuitry to build a microphone with a similar graphene diaphragm.

One big advantage of graphene is that the atom-thick sheet is so lightweight that it responds well to the different frequencies of an electronic pulse, unlike today’s piezoelectric microphones and speakers. This comes in handy when using ultrasonic transmitters and receivers to transmit large amounts of information through many different frequency channels simultaneously, or to measure distance, as in sonar applications.

“Because our membrane is so light, it has an extremely wide frequency response and is able to generate sharp pulses and measure distance much more accurately than traditional methods,” Zhou said.

Graphene membranes are also more efficient, converting over 99 percent of the energy driving the device into sound, whereas today’s conventional loudspeakers and headphones convert only 8 percent into sound. Zettl anticipates that in the future, communications devices like cellphones will utilize not only electromagnetic waves – radio – but also acoustic or ultrasonic sound, which can be highly directional and long-range.

“Graphene is a magical material; it hits all the sweet spots for a communications device,” he said.

You never know who can give you a new idea for your research, from the news release,

When Zhou told his wife, Jinglin Zheng [also a physicist], about the ultrasound microphone, she suggested he try to capture the sound of bats chirping at frequencies too high for humans to hear. So they hauled the microphone to a park in Livermore and turned it on. When they slowed down the recording to one-tenth normal speed, converting the high frequencies to an audio range humans can hear, they were amazed at the quality and fidelity of the bat vocalizations.

“This is lightweight enough to mount on a bat and record what the bat can hear,” Zhou said.

Bat expert Michael Yartsev, a newly hired UC Berkeley assistant professor of bioengineering and member of the Helen Wills Neuroscience Institute, said, “These new microphones will be incredibly valuable for studying auditory signals at high frequencies, such as the ones used by bats. The use of graphene allows the authors to obtain very flat frequency responses in a wide range of frequencies, including ultrasound, and will permit a detailed study of the auditory pulses that are used by bats.”

Zettl noted that audiophiles would also appreciate the graphene loudspeakers and headphones, which have a flat response across the entire audible frequency range.

“A number of years ago, this device would have been darn near impossible to build because of the difficulty of making free-standing graphene sheets,” Zettl said. “But over the past decade the graphene community has come together to develop techniques to grow, transport and mount graphene, so building a device like this is now very straightforward; the design is simple.”

Here’s a link to and a citation for the paper,

Graphene electrostatic microphone and ultrasonic radio by Qin Zhou, Jinglin Zheng, Seita Onishi, M. F. Crommie, Alex K. Zettl. Proceedings of the National Academy of Sciences, 2015; 201505800 DOI: 10.1073/pnas.1505800112

This paper is behind a paywall.