BIODEGRADABLE VASCULAR STENTS – A NOVEL PRODUCTION TECHNOLOGY

Pure iron is considered to be a suitable material for the production of the new generation of vascular stents, which are absorbed by the body within 6-8 months, unlike the present ones which are “for life”. This presentation discloses the results of a new production technology developed to manufacture them.

Standard stents production is a well established procedure of laser-cutting a metal tube with an expensive 5-axis machine, resulting in high production costs, even for long-running batches.

An electroforming deposition could be a preferred manufacturing way, appreciably reducing the expenses and lowering costs. Since a commercial iron electroforming process is unavailable, it had to be developed, to be capable of producing the mechanical properties necessary for proper use. This involved the need to define various working parameters, including heat treatment. The resulting material has the same elongation and tensile yield strength as the standard stents material, Stainless Steel 316.

As for the 3D shape forming, a novel technology has been conceived and demonstrated to give the fine and intricate geometry in a reproducible and inexpensive way. An unusual way of setting up the photoresist on the mandrel, yielding a 3D structure without resorting to expensive multi-axis devices was designed, opening an entirely new field of use. For this, a 200µm thick photoresist foil is exposed to an appropriate design, comprising many units of 2D patterns. Each individual unit is then applied to a cylindrical mandrel and developed, in order to reveal the metallic substrate for the desired geometry electroforming. After electroforming, appropriate processes enable the tubular device to be easily sled off the reusable mandrel. A chemical polishing finishing procedure renders the surface quality as smooth as needed.