Just how small can a QR code be? Small enough that it can only be recognised with an electron microscope. A research team at TU Wien, working together with the data storage technology company Cerabyte, has now demonstrated exactly that. The QR code covers an area of just 1.98 square micrometers — smaller than most bacteria. The record has now been verified and officially entered into the Guinness Book of Records.

The technology has enormous potential for long-term data storage: Conventional magnetic or electronic data storage systems often have lifespans of only a few years. But if information is written bit by bit into ceramic materials, it can endure for centuries or even millennia.

As small as possible — and as stable as possible

“The structure we have created here is so fine that it cannot be seen with optical microscopes at all,” says Prof. Paul Mayrhofer from the Institute of Materials Science and Technology at TU Wien. “But that is not even the truly remarkable part. Structures on the micrometer scale are nothing unusual today — it is even possible to fabricate patterns made of individual atoms. However, that alone does not result in a stable, readable code.”

Individual atoms can diffuse, move to other positions, fill gaps — and the stored information is lost. “What we have done is something fundamentally different,” Mayrhofer explains. “We have created a tiny, but stable and repeatedly readable QR code.”

Thin ceramic films

A crucial factor is the choice of the right material. “We conduct research on thin ceramic films, such as those used for coating high-performance cutting tools,” explain Erwin Peck and Balint Hajas, who played key roles in achieving the world record. “For high-performance tools, it is essential that materials remain stable and durable even under extreme conditions. And that is exactly what makes these materials ideal for data storage as well.”

Using focused ion beams, the team milled the QR code into a thin ceramic layer. The individual pixels are only 49 nanometers in size — roughly ten times smaller than the wavelength of visible light. The code is therefore completely invisible; its details cannot be resolved using visible light at all — much like it is fundamentally impossible to feel Braille letters with the thick sole of an elephant’s foot. But when examined with an electron microscope, the QR code could indeed be read reliably.

The storage density of this method is remarkable: On the area of a single A4 sheet of paper, more than 2 terabytes of data could be stored in this way — and unlike conventional storage media, such ceramic data carriers are virtually durable indefinitely and require no energy to preserve the stored information.

Long-term storage for the information age

“We live in the information age, yet we store our knowledge in media that are astonishingly short-lived,” says Alexander Kirnbauer. Magnetic and electronic data carriers often lose information after just a few years; without constant energy input, cooling, and regular data migration, the traces of our time fade away. Earlier civilisations carved their knowledge into stone — and those messages have survived for thousands of years.

“With ceramic storage media, we are pursuing a similar approach to that of ancient cultures, whose inscriptions we can still read today,” says Alexander Kirnbauer. “We write information into stable, inert materials that can withstand the passage of time and remain fully accessible to future generations.”

It is also crucial that these data remain intact without any energy input and without cooling — in contrast to today’s data centers, which require enormous amounts of electrical energy and thus contribute significantly to global CO₂ emissions.

Entering the Guinness Book of Records

The world record — including the readout process using an electron microscope — was carried out jointly by TU Wien and Cerabyte in the presence of witnesses and confirmed by the University of Vienna as an independent verifier. TU Wien not only provides state-of-the-art materials science laboratories, but also the high-tech electron microscopes of USTEM, the university’s electron microscopy centre. The record has now been reviewed and officially recognized by Guinness. The newly measured QR code is only 37% the size of the previous world record holder.

“The now confirmed world record marks just the beginning of a very promising development,” says Alexander Kirnbauer. “We now aim to use other materials, increase writing speeds, and develop scalable manufacturing processes so that ceramic data storage can be used not only in laboratories but also in industrial applications. At the same time, we are investigating how more complex data structures — far beyond simple QR codes — can be written robustly, quickly, and energy-efficiently into ceramic thin films and read out reliably.”

This research thus opens up a realistic path toward a more climate-friendly data future — one in which information can be stored permanently, securely, and with minimal energy consumption.

Contact:

Prof. Paul Mayrhofer
Institute of Materials Science
TU Wien
+43 1 58801 30811
paul.mayrhofer@tuwien.ac.at