Fabrication of biodegradable thin film stents of magnesium alloys by magnetron sputtering

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The proposal is planed as a follow-up of the project Fabrication of biodegradable thin film stents made of magnesium alloys by magnetron sputtering. It describes the fabrication and characterization of planar, freestanding, structured thin films of biodegradable magnesium based alloys fabricated by magnetron sputtering and by photolithographic methods, as well as the development of suitable joining technologies for the production of stents and the characterization of these components by fatigue tests. Biodegradable materials form a group with increasing importance in the field of implant materials, which are applied where a permanent implant is not required or even disadvantageous, e.g. for fixation of bone fractures or treatment of children with stents who cannot get permanent implants due to their non-terminated growth.When using magnesium based alloys as biodegradable implant material, one challenge is the local control of the dissolution behaviour (corrosion). Many conventional alloys which are prepared by casing techniques show on the one hand a very localized dissolution and on the other hand a dissolution that proceeds with a too high rate which leads to an impairment of the implant's functionality and also might lead to a damage of the surrounding tissue. In the previous project a well-directed dissolution of the material was intended to be achieved by multilayer systems and gradient layers. It was shown that this approach is not feasible. However, it could also be shown that the dissolution of the magnetron deposited alloys was much more homogeneous compared to cast alloys. Due to these reasons the focus of this proposal is the identification of a suitable alloy which on the one hand does not contain any alloying elements that are harmful to the human metabolism and on the other hand shows a suitable dissolution behaviour in the human body while having a sufficient ductility to be implanted without difficulties at the same time. Within the scope of this project the fatigue behaviour of suitable alloys shall be investigated additionally in order to be able to make a statement about the mechanical behaviour in a corroded state.