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

该提案计划作为磁控溅射制造镁合金生物可降解薄膜支架项目的后续项目。它描述了用磁控溅射和光刻方法制备的可生物降解镁基合金的平面、独立、结构薄膜的制备和表征，以及用于支架生产的合适连接技术的发展和这些部件的疲劳试验表征。可生物降解材料是种植材料领域中越来越重要的一类材料，它应用于不需要永久性种植体甚至是不利的情况下，例如骨折的固定或由于支架生长不终止而无法获得永久性种植体的儿童的治疗。当使用镁基合金作为生物可降解植入材料时，一个挑战是局部控制溶解行为（腐蚀）。许多用套管技术制备的传统合金一方面表现出非常局部的溶解，另一方面表现出溶解速度过快，从而导致植入物功能的损害，也可能导致周围组织的损伤。在之前的项目中，通过多层系统和梯度层来实现材料的定向溶解。结果表明，这种方法是不可行的。然而，也可以表明，与铸造合金相比，磁控管沉积合金的溶解更加均匀。由于这些原因，本提案的重点是确定一种合适的合金，一方面不含任何对人体新陈代谢有害的合金元素，另一方面在人体中表现出合适的溶解行为，同时具有足够的延展性，可以毫无困难地植入。在本项目范围内，应对适当合金的疲劳行为进行额外的研究，以便能够对腐蚀状态下的机械行为做出陈述。

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.