The EU will begin requiring all medical devices beginning in May to carry a unique identifier that can be tracked throughout the supply chain. Image courtesy of TRUMPF Inc.

Even on medical devices made from highly reflective materials, the TruMicro 2000 can produce corrosion-resistant marks that are permanently high contrast. Source: TRUMPF Inc.

Laser marking and UDI systems

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The Medical Device Regulation (MDR) is set to take effect in May. (The law was supposed to take effect last May, but it was delayed due to the COVID-19 pandemic).

UDIs must be used by medical device manufacturers under the MDR, similar to those required by the US Food and Drug Administration in 2013. MDR mandates that all medical devices be labelled with a unique lasitlaser.de, globally recognized identifier for tracking from the point of manufacture through distribution to final use. In addition to facilitating medical device recalls, the system makes adverse event reporting easier, improves supply chain security, and prevents medical errors.

In addition to marking the device, the identifier must appear on all levels of packaging (boxes, cartons, and sterile packages). The identifier must appear in either a human-readable number or an automatic identification code, depending on the environment. Barcodes and Data Matrix codes can be used.

In addition to sharing product information in a standardised way, medical device manufacturers will be required to submit product UDIs to a centralised repository, the European Database for Medical Devices (Eudamed).

Labelling directly on medical devices presents more of a challenge than marking packaging. These devices are small, manufactured in large quantities, sterile, and made of tough materials, such as titanium and stainless steel.

It is ideal to use lasers for marking. Stainless steel, aluminium, plastics, and organic materials can all be marked with lasers.

TRUMPF Inc.’s TruMicro Mark 2000 laser, for example, produces extremely short pulses (0.40 to 20 picoseconds) of high energy. Despite repeated cleaning and sterilisation, it still maintains a highly contrasted appearance.

In order to process cold materials, the TruMicro Mark 2000 emits pulses that are short enough. The laser energy absorbs faster than the surrounding material can heat up, which means that the material can be machined before thermal processes take place. The high-power laser pulses used to mark the medical device first form a nanostructure on its surface. Thus, this rough surface creates a kind of light trap, reducing diffuse scattering to the point where the mark becomes dark black in hue, a process known as black marking.

This method has the advantage of preventing corrosion by re-forming the protective chromium oxide layer of steel after processing. Markings in black are ideal for rust-free stainless steels, aluminium, titanium, copper, brass, and chrome-plated plastics.

In order to ensure that black markings remain legible and durable in the presence of cleaning agents and high temperatures, medical device assemblers may want to use targeted passivation. In a nitric or citric acid bath, highly reactive components (such as free iron ions) are removed from the surface and an even better corrosion resistance layer is formed by forming a new and clean layer of chromium oxide. This process involves simultaneous cleaning of the surface and dissolving of sulfurs. If laser marking parameters are selected precisely, passivation may not be necessary.

Through TRUMPF’s TruTops marking software, manufacturers can create UDIs that comply with industry standards. To present their data in UDI format, engineers may use any of the three accredited labelling standards (GS1, HIBC, and ISBT 128). For quality control purposes, manufacturers can also use the software to scan and read UDIs on finished devices.