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

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. Normal paper or foils are printed with two layers of a conductive organic polymer as electrodes. In between there is a piezoelectric layer as an active element, which causes the paper or film to vibrate. Loud and clear, the sound is generated by the displacement of air. Both 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 is why the researchers at the Institute for Print and Media Technology have been looking for a new way since May 2017 - towards cost-effective mass production.

The aim of their most recent project, “Roll-printed loudspeaker paper” (T-Paper for short) was therefore to transfer sheet production to roll production. “Researchers from the fields of print media technology, chemistry, physics, acoustics, electrical engineering and economics, who come from six nations, have developed a continuous, highly productive and safe roll production of loudspeaker tracks”, reports project manager Georg C. Schmidt. The roll-to-roll (R2R) printing process was not only used for this, but inline technologies were also developed for further process steps, such as the lamination of functional layers. “This is how electronics can be embedded in the paper - invisible and protected,” says Hübler. In addition, an inline polarization of the piezoelectric polymer layers was successful for the first time and complete inline process monitoring of the printed functional layers was possible. The final project results were published in January 2021 in the renowned specialist journal “Advanced Materials”.

Long and light paper speaker tracks for museums, advertising and Industry 4.0

The potential of speaker paper was expanded to include other areas of application in the T-Paper project. This means that meter-long loudspeaker installations can now be produced in the form of a track or a circle (“T-RING”). “In our T-RING prototype, a four-meter-long track with 56 individual speakers was connected to seven segments and shaped into a circle, which makes a 360 ° surround sound installation possible,” says Schmidt. The loudspeaker track including the printed wiring only weighs 150 grams and consists of 90 percent conventional paper that can be printed in color on both sides. “In this way, inexpensive infotainment solutions are now possible in museums, at trade fairs and in the advertising industry. In public buildings, for example, a very homogeneous sound system for long stretches such as corridors is possible. But the process technology itself could also be of interest for other areas, for example for the production of inline measuring 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 +”.

Multimedia

A classification of the research results on the subject of “printed loudspeakers” in the “T-Paper” project by Dr. Georg C. Schmidt is available in the series “Statements from Research”. The video can be found on the Chemnitz University of Technology YouTube channel: https://www.youtube.com/watch?v=SojLNZB1-8g.

Original publication

Georg C. Schmidt, Pramul M. Panicker, Xunlin Qiu, Aravindan J. Benjamin, Ricardo A. Quintana Soler, Issac Wils, Arved C. Hübler: Paper-Embedded Roll-to-Roll Mass Printed Piezoelectric Transducers, Advanced Materials - Wiley Online Library, 2021, DOI: https://onlinelibrary.wiley.com/doi/10.1002/adma.202006437.

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