Nitinol Micro Machining Utilizing Ultra-Short Pulse Lasers

Since the advent of micro machined implants made of Nitinol, like stents or heart valve frames, laser micro cutting is the technology of choice to fabricate these implants. Starting with flash-lamp pumped Nd:YAG lasers, nowadays fiber lasers are the work horses in the fabrication of Nitinol micro implants. Just recently another laser technology - ultra-short pulse (USP) lasers - became available at a power level and reliability being well suited for serial production of Nitinol implants.

Ultra-short pulse lasers allow micro cutting of Nitinol with a lateral resolution, i.e. kerf widths, well below 10 µm and minimal impact on the properties of the surrounding material. In this work we report how these superior properties of USP lasers affect the engineering work space for designing medical implants with respect to kerf and strut widths, wall thickness and tubing diameter. Furthermore, we quantify the impact on material properties.

Ultra-short pulse lasers allow not only for micro cutting but also for micro machining, meaning removing only parts of the entire wall thickness instead of cutting through. We show how this technology can be used to realize geometries in Nitinol which are not achievable with other technologies at the micrometer scale like chamfers, traumatic and atraumatic tips, spheres, and grooves.