Medical Design Engineers Can ‘Make Their Mark’ with Transfer Pad Imprinting

CI Medical Inc., Norton, MA

Eventually, many design engineers who create new medical devices are faced with choosing a method with which to mark or brand their products. At the end of the complex task of creating and vetting a new product, marking is often an afterthought, because, after all, “How hard can it be?” However, as many discover over time, marking is one of those details that bears some deliberation. Whether it’s a logo impression, color identification on an instrument, or graduation marks on catheters or guidewires, imprint precision, image crispness, and permanent adhesion are extremely important. There are several effective ways to mark a product, but there are limitations.

Marking techniques like laser etching, screen printing, or inkjet printing—while certainly acceptable in select instances—may have drawbacks or limitations with regard to irregular surfaces; highly-intricate, multi-color imprints; performance on heat-sensitive substrates; or adherence to non-stick substrates. Laser etching physically mars the product, actually removing something from the substrate’s surface, which may be undesirable for some devices or implantables. Also, due to heat generated in the laser etching process, this method generally cannot be used on polyurethanes, polyethylene terephthalate (PET), or polyethylenes (PE), which can melt. Screen printing, which requires a flat surface, cannot offer high quality or crispness of the printed image. Likewise, computer inkjet printing methods may lack image precision, although this process can be helpful when the situation requires serialization or printing a unique identification mark on each individual part for traceability.

Unlike these other marking techniques, transfer pad imprinting as a method of identification and/or labeling medical devices is growing in popularity with medical design engineers due to its versatility, precision, and multi-color markings. Able to conform to any surface, transfer pad imprinting can be performed on virtually ANY medical device—regardless of size, substrate, or surface irregularity. Tight tolerances, 360° rotational markings, and precise registration of multi-color images can all be easily achieved through pad printing. In addition, automatic pad cleaning between cycles can ensure the most precise, consistent markings possible on difficult medical device components such as catheters, medical grade heat shrink, and medical grade fabrics. The permanent markings imparted by pad imprinting are impervious to chemical, heat, gas, and other sterilization techniques. Biocompatible inks are used on medical devices including catheters, microcatheters, tubing, trocars, cannulas, heat shrinks, syringes, and other surgical instruments. These Class VI Medical grade inks comply with FDA standards for products that may come in physical contact with the human body.

With the plethora of slippery surfaces, pad imprinters have had to become increasingly creative with the use of new, specialized inks and highly precise device markings on unusual surfaces. Plasma gas pretreatment is an effective solution for medical ink adhesion challenges associated with plastic substrates that have chemically inert and non-porous surfaces with low surface tension. Through plasma gas pretreatment, specialty medical grade inks enable printing on such formerly “unprintable” substrates as fluorinated ethylene propylene (FEP), polytetrafluoroethylene (PTFE), expanded polytetrafluoroethylene (ePTFE), Radel, polyether ether ketone (PEEK), polypropylene (PP), and PE (both high- and low-density). In the plasma gas pretreatment process, a combination of gases treats the surface of the substrate and temporarily modifies the molecular surfaces of substrates to increase the surface tension and promote permanent medical ink adhesion.

Because of the many challenges of surface shape, substrate, corporate branding, measured precision required, and, oftentimes, the sheer science involved, design engineers soon discover that product marking is not quite as easy as it appears. And, due to the flexibility, versatility, precision, and repeatability imparted by transfer pad imprinting, more design engineers are choosing to “make their mark” with this method.

This article was written by Bruce Mahan, Engineering Manager, at CI Medical Inc., Norton, MA. For more information, Click Here .

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