Catheters are increasingly complex in their designs—for example, combined materials, multiple lumens with different shapes, characteristics, and functions, and inner and outer diameters that continue to get smaller, but with added functionality. These needs make laser processing of medical catheters a high-precision procedure with incredibly tight, single-micron tolerances.
Laser processing procedures that medical device manufacturers (MDMs) commonly request are the reduction the outer diameter (OD) of the catheter and laser drilling or cutting precise micro features into the body of the catheter:
- Outer diameter reduction—laser ablation removes material from the exterior of the catheter in sub-micron-thick layers, one at a time, with extraordinary precision. This technique works well on metals and polymers at both the macro and micro scales for a wide variety of medical products, including neurovascular, cardiovascular, and catheterization products.
- Laser-cut features—laser beams remove material to create access ports to components within the catheter, or to expose functional parts. Lasers drill through one layer of the catheter structure at a time to create 1-2 micron-wide holes or other shapes to the desired depth within the catheter, or completely through the material. Laser cutting is preferred for tiny features in infusion catheters, balloon catheters, and embolic protection filters.
High Precision Is a Must
The type of laser selected and the process (laser cut, drill, ablation) depends largely on the features being created and the catheter material selected.
Laser ablation is a popular approach because of the many ways it can be utilized. Excimer and diode-pumped lasers ablate, or vaporize, the material before it can start to melt, which greatly reduces or eliminates any physical or chemical changes to the catheter material. For example, laser ablation is frequently used to reduce the OD of the catheter tube. This creates clearance so electrode rings can be slid onto the tube and, if applicable, expose satellite lumens inside the catheter so wire leads can be inserted into the lumens and attached to the electrodes. Ultrashort picosecond or femtosecond lasers are often used for catheters that are made from sensitive materials to further reduce risk of damage or heat-affected zones that might alter performance or durability.
Multiple Material Challenges
A technical challenge with processing catheters manufactured from polymer laminates, such as PEEK, polyimide, Pellethane®, Pebax®, or PTFE, is penetrating to exactly the correct depth within the catheter body. Even the slightest variances can affect performance. Steerable catheters, for example, have a stainless-steel braid that cannot be damaged when ports are being laser-drilled through the exterior surface. For laser processing multi-lumen catheter designs, another challenge is properly aligning and holding the catheter body in place so there is no material damage during processing. Clients often request the drilling of tiny arrays of blind holes in the outer wall of certain lumens, without penetrating the inner wall, to create electrical connections with conductive sub-layers or to open up access to a satellite lumen. Such high-precision drilling may require optical inspections to assure quality and performance.
As catheters continue to become smaller and more complex, laser systems must also advance to attain the performance and functionality that MDMs expect from these devices. This often involves working directly with the MDM engineering teams to create one-of-a-kind, proprietary laser processes and systems, making extraordinary designs a reality.