Ultra-Short Pulse Lasers And Their Application Potential Micromachining Nitinol Implants

The fabrication of medical implants like stents or heart valve frames is unconceivable without laser micromachining. In recent years the technology of ultra-short pulse (USP) lasers achieved a quality, power level and reliability, making this universal tool more and more suitable for use in serial production of Nitinol implants. The precision of this laser technology is unrivalled by other micromachining processes, offering a wide range of applications in micrometer scale, such as extremely small kerf widths (< 10 µm), high aspect ratios (> 20) and minimal effect on the properties of the surrounding material.

The versatility of ultra-short pulsed lasers allows much more than the conventional laser cutting of stents. The technology is being used for almost every kind of micromachining - like lathing, drilling, chamfering or surface texturing. In this work, we report on our recent development in this field and in which way the USP laser properties affect the designing and engineering of these medical implants. We show how this technology can be used to realize geometries and features in Nitinol, which are on the one hand not achievable with other micromachining technologies and on the other hand enable the precise adjustment of the mechanical behavior of the implants. To characterize the mechanical as well as the phase transformation behavior of the laser machined Nitinol implants, we performed bend and free recovery, differential scanning calorimetry and radial force testing. This allows to quantify the impact of the processing on material properties.