Use of Sheet Material for Rapid Prototyping of Cardiovascular Stents

Manufacturing of cardiovascular stents most commonly involve the use of tubular precursors and laser microcutting of the stent mesh, followed by chemical and electrochemical surface treatments. For mass manufacturing purposes, this production route is well-established, while for small batch or prototype production it proves to be cumbersome. Especially concerning newly developed alloys based, the production of microtubes is time consuming and highly costly. On the other hand, production of these new alloys in sheet metal form is a simpler approach, since the process uses non-dedicated tools and is easier as opposed to extrusion and tube drawing. Accordingly, in this work, the use of sheet material as precursor for rapid prototyping of cardiovascular stents is proposed. In particular, a ns-pulsed fiber laser is used for cutting permanent AISI 316L. Laser microcutting conditions are investigated in terms of generated spatter and kerf geometry. Chemical etching is employed to clean the dross generated around the cut kerf. A novel stent geometry allowing for transforming the sheet material to a tubular form is employed to produce prototype stents

Lasers in the manufacturing of cardiovascular metallic stents: Subtractive and additive processes with a digital tool

Laser beams can be manipulated to achieve different types of interaction mechanisms with metals allowing them to heat, melt, vaporize, or ablate them. Today's laser sources are robust, fast-addressable optoelectronic devices, easily integrated into automation systems along with sophisticated CAD/CAM solutions. Being a photonic digital tool, the laser beam is a fundamental tool for Industry 4.0 and is already widely exploited in the manufacturing of metallic stents. The conventional manufacturing method of laser cutting employs a subtractive method to cut the stent mesh on tubular feedstock. On the other hand, laser beams can be exploited to melt metallic powders to produce stent geometries in a layer-by-layer fashion. The present work provides a short state of the art review concerning the works focusing on the two laser-based manufacturing processes underlining the evolution of the laser source types and used materials. The work provides insights into the future opportunities and challenges that should be faced by the manufacturing research communities in the light of improving the biomedical device performance by exploiting the possibilities provided by the digital tool

Laser microcutting of sheet metal for prototyping expandable stent-like structures in permanent and biodegradable alloys

For biomedical devices, cardiovascular stents in particular, the employed material plays a crucial role in controlling the mechanical and biological behavior. However, the material properties are directly influenced by the production route and the stent geometry. Conventional stent manufacturing route consists of laser microcutting of microtubes. Microtube extrusion and drawing are both costly and time consuming at a prototyping level. Instead, sheet material can be obtained relatively easier using non-dedicated tooling. This work, proposes the use of laser microcutting of thin sheets for producing mesh structures that can be expanded in a tubular form with the aim of assessing processability and expandability. AISI 316L stainless steel and AZ31 Mg alloy are studied representing the well-established permanent stent material and a candidate biodegradable alloy. Surface finishing is carried out with chemical etching. A conventional balloon catheter is used for comparative expandability tests