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

这项建议是磁控溅射镁合金生物可降解薄膜支架项目的后续计划。它描述了磁控溅射和光刻方法制备的可生物降解的镁基合金平面独立结构薄膜的制备和表征，以及用于生产支架的合适连接技术的发展和通过疲劳试验对这些部件进行表征。在植入材料领域，可生物降解材料是一类越来越重要的材料，这些材料被应用于不需要或甚至不利于永久植入的领域，例如用于固定骨折或使用支架治疗因未终止生长而无法获得永久植入的儿童。当使用镁基合金作为可生物降解植入材料时，一个挑战是局部控制溶解行为(腐蚀)。通过套筒技术制备的许多传统合金一方面表现出非常局部性的溶解，另一方面表现为溶解速率太高，导致植入物的功能受损，还可能导致周围组织的损害。在以前的项目中，通过多层体系和梯度层来实现材料的良好定向溶解。结果表明，这种方法是不可行的。然而，也可以看出，与铸造合金相比，磁控沉积合金的溶解更均匀。由于这些原因，本建议的重点是确定一种合适的合金，这种合金一方面不含有任何对人体新陈代谢有害的合金元素，另一方面在人体内表现出适当的溶解行为，同时具有足够的延展性，可以毫无困难地植入体内。在本项目的范围内，应另外调查合适合金的疲劳性能，以便能够对腐蚀状态下的机械性能作出说明。

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.