Laser colour-marking system prints nanometric codes on products

Funded by FAPESP between 2001 and 2013, the startup mastered the technology for manufacturing lasers used in industrial applications but decided to advance their interests further. With support from FAPESP’s Innovative Research in Small Business Program (PIPE), BR Labs is creating a laser colour-marking system.

The project, which completed PIPE Phase 1 in February 2017, uses a pulsed titanium-sapphire (Ti:sapphire) laser to produce colour markings on the surface of different materials. Physicist Fatima Maria Mitsue Yasuoka, principal investigator for the project, explains that the laser emits ultrashort pulses that last only a few femtoseconds (1 fs = 10-15 s).

According to Yasuoka, the many applications of colour-marking lasers range from logos on consumer goods to barcodes for quality control in high-volume production lines. For example, this technology can be used to apply a two-dimensional barcode, such as a QR Code, that is nanometric and hence invisible to the naked eye but readable by a smartphone.

The system’s precision is impressive, she says. For example, one of several laboratory tests involved engraving Tarsila do Amaral’s painting Operários on a 10 mm x 6 mm stainless-steel plaque.

The high-intensity light beam modifies the surface of the material, creating nanometric structures (on the order of 10-9 m) called ripples. “These periodic ripples etched on the surface of the material by ultrafast radiation create specific colour patterns,” Yasuoka says.

This phenomenon occurs because the ripples behave like a diffraction grating, so that natural white light strikes the ripples and disperses into its constituent wavelengths, each of which appears as a different colour to the human eye. Because the laser alters the structure of the material, the marking is permanent. “The only way to remove it would be by grinding the surface,” Yasuoka notes.

Initially the project’s aim was to offer this service to the Brazilian market at a price competitive with existing services offered abroad. “Once the firm is able to offer colour marking, customers who want to buy the system itself will show up,” Yasuoka predicts.

The prospect of cost savings has already led a number of firms to partner with BR Labs, which is currently based in São Carlos, in the interior of São Paulo State. “The cost of a titanium-sapphire laser today is about US$200,000, excluding all the other components of the system, such as software, scanner and galvanometer, for example,” she says.

Yasuoka expects that the price at which the service can be offered to the market cannot be known until completion of the second project, approved by PIPE, which began in August 2017 and is scheduled to end in April 2018.

However, she is sure that the partnerships she has established will be crucial to lowering production costs in the future. “Group purchasing of raw material makes the price more affordable,” she says. “I acquired experience over several years working in business, so I know mastering the technology and bringing it to Brazil is a feasible project.”

Besides completing postdoctoral studies at the University of São Paulo’s São Carlos Physics Institute (IFSC-USP) and teaching at several universities, Yasuoka was a researcher and project manager at Opto Eletrônica for 13 years before being invited to work at BR Labs.

“BR Labs was based in Campinas and stood out as a pioneer of technological innovation in photonics,” she recalls. “But they needed an administrator who could spend longer on the premises. I don’t teach full time, so I was able to undertake this administrative role as well.”

Entrepreneur-researcher Yasuoka now wants to bring her professional experience to the project by fostering a rare interaction between academia and industry. “We’re bringing in university students and pushing out into a frontier area,” she says.

BR Labs is currently incubating at ParqTec in São Carlos, but also benefits from cooperation with the Federal University of São Carlos, IFSC-USP and USP’s Engineering School there, all of which have tools that are indispensable for research in the field of nanotechnology, such as scanning electron and atomic force microscopes, which the vast majority of companies cannot afford.

Collaborations are fundamental to the success of the project, and Yasuoka can also find these in the academic community. “I’m building a strong team to achieve the goals of PIPE Phase 2,” she explains.

“I need one engineer with the necessary knowledge to take care of the electronic controls for the system, another who can write software, and a materials engineer, as well as a physicist capable of understanding everything and putting it all together.”

Tasks that appear daunting to most new entrepreneurs fresh out of academia, such as establishing partnerships, calculating costs, and even preparing projects for PIPE – “Opto was one of the first to submit projects and had several approved” – were already part of Yasuoka’s routine when she decided to take on this new research project.

Her main challenge was in the lab: “Proving we had the capacity to take a range of materials and mark them with predefined colours using a femtosecond laser”. Although she had worked with lasers before, this was her first experience in surface marking, and she led a team composed of an electronic engineer, physicists and an undergraduate student who was part of a scientific initiation program.

Yasuoka recalls that throughout Phase 1 of the project she worked with steel, gold, platinum, aluminum, bronze, copper, brass, and even acrylic, among other materials. Very precise control of structural alterations is crucial to obtaining the right colour, she explains, and different controls are required for each kind of surface: “Laser power is different and microscope scanning speed changes, as do the number of repeated scans and the polishing technique.”

For this reason, the next step entails creating a protocol for each type of material. “The goals set to date have been achieved. In Phase 1 we showed we could engrave materials in different colours".

"We hadn’t yet managed to master the shades of each colour, but in Phase 2 we plan to upgrade the software in order to assure better control. The final objective is to reach a standard that can be replicated serially,” she concludes.