Optimization of laser micromachining process for biomedical device fabrication

Laser machining is commonly used for fabrication of medical devices with microscale features, including vascular stents, drug delivery devices, and scaffolds for tissue engineering with controlled pore size and porosity. The process can also be used to produce structured scaffolds for controlling cell growth, orientation, and location. Moreover, lasers may be used to fabricate complex channel nets in which cells are subsequently seeded or to pattern channels for microfluidic devices. Traditionally, these micro devices were fabricated using silicon substrates, but recently the use of titanium allowed to produce more robust devices at a reasonable cost. In particular, the high quality surfaces that can be obtained with laser machining reduce the liquid flow turbulence and avoid micro cavities formation, critical for bacteria proliferation. The present research reports the results of an investigation on the process capability of laser ablation to produce micro pockets fabricated on titanium sheet (0.5 mm thick). A first experimental campaign was designed for identifying a set of laser ablation cycles able to realize the micro pockets by changing the process parameters as scanning speed, laser power, q-switch frequency, loop number, and duty cycle. Moreover, a process optimization was executed in order to produce the pockets with a highly flat surface. The results were acquired by a confocal laser scanning microscope (CLSM) to obtain high-resolution images with depth selectivity and were analyzed with statistic methods for the identification of the best parameter configuration.