Laser marking is a useful tool for implementing the mandatory unique device identification (UDI) as required by medical legislation to protect against counterfeiting. In accordance with this, ELIX Polymers has developed special medical pre-coloured acrylonitrile butadiene styrene (ABS) formulations based on existing biocompatible materials M203FC or M205FC, to maximise laser marking results on medical devices and to ensure full compliance with regulations.
EU’s new Medical Device Regulation (MDR) and US’ Code of Federal Regulations Title 21 on labelling of medical devices (21 CFR 801 Subpart B) enforce the use of a UDI system to be placed on medical devices and on their packaging to reduce the risk of counterfeiting, improve traceability and better manage incident reporting, device recalls and other adverse events.
Several medical devices must be directly marked with a unique device identifier (CFR 21 Sec. 801.45 or EU MDR Part C 4.10 about the UDI system in reusable devices); in general, if the devices are intended to be used more than once and be cleaned or disinfected before each use.
Laser marking makes it possible to attach a unique identifier to the medical device and offers a series of additional advantages compared with alternative technologies such as labelling, pad printing, or hot stamping.
Some materials can be more easily laser-marked than others, whereas others provide poor results. It is, therefore, critical to select the correct medical materials and subsequently adapt the laser equipment type and settings accordingly. In addition to the material, special attention should be given to its colour; in particular, the colour formulation and its compatibility with the base material to create certain laser marking effects or colours of contrast.
Compliant ABS polymers
ABS polymers are widely used to produce external enclosures, covers or shells for reusable devices. ABS is a laser-markable material where correct laser settings adapted to the ABS material produce acceptable laser marking results. But there may be some limitations as the text or information to be laser-marked could produce an undesired colour, level of contrast or an unexpected resolution. In addition, there is an important risk of no longer complying with regulations.
ELIX Polymers, therefore, has developed special medical ABS formulations based on M203FC and M205FC materials that optimise laser marking to achieve a specific colour change and a targeted level of contrast over a given colour background that is fully compliant with regulations.
These special ABS formulations are also particularly valuable when other relevant material properties must be maintained along with laser marking optimisation, such as, the biocompatibility requirement of ISO 10993.
Since ABS and its colour are both important factors for obtaining the required laser-marking effect, a critical aspect of this type of development is to create a database selection of available pigments with the highest performance under different laser systems. Several combinations of material-colour samples must be prepared and pass a laser processing qualification process.
Before this step, a core aspect is to obtain an optimal dispersion of the selected colour pigments of the colour formulation in the ABS material formulation. The mix of colour masterbatches with ABS material in natural colour during the injection moulding process cannot guarantee the same level of colour homogeneity as pre-coloured ABS. The reason for this resides in a better dispersion of pigment powders in the ABS matrix during the compounding extrusion process that is required for producing pre-coloured ABS.
For medical devices requiring biocompatibility, among the available pigments used for optimising laser marking contrast, only those with biocompatibility properties and fall within the legal admissible concentrations can be used to guarantee compliance with the required medical regulation. The ELIX Product Stewardship department provides essential support for this task, which also adds value by conducting a constant surveillance of admitted substances and concentrations and by guaranteeing that the complete formulation, including the colour formulation, stay within legal limits. Re-combined validated pigments provide new colour formulations for medical ABS, where laser marking contrast is enhanced while guaranteeing the same target colour material is maintained.