血管支架不定形碳膜脱层现象实验及有限元分析

目的 研究不定形碳涂层的血管支架在握压-扩张过程中发生涂层脱层的现象，从材料选择和尺寸设计方面避免脱层的发生。方法 通过化学气相沉积法在金属血管支架上沉积生成不定形碳膜，实验模拟该涂层血管支架的握压-扩张过程，并通过电子扫描显微镜观察涂层发生脱层的情况。采用有限元方法分析不定形碳膜在血管支架握压-扩张过程中发生脱层的受力机制及影响因素。结果 有限元结果能够较好吻合实验现象。不定形碳膜厚度决定了支架各处脱层的难易程度，以及脱层的发生形式。不定形碳膜弹性模量越大，支架越容易发生脱层。此外，支架的弹性模量也会对支架脱层产生影响，且在不同位置处影响规律不同。结论 在血管支架涂层时，需要仔细设计不定形碳膜厚度以及合理匹配不定形碳膜和支架的弹性模量以避免脱层的发生。
Objective To investigate the phenomenon of amorphous carbon coating delamination during crimping and expansion of the vascular stent, and study how to avoid such phenomenon from both material selection and dimension design of the stent. Methods Amorphous carbon coatings were deposited onto a bare metal stent by chemical vapor deposition method, and then to simulate the crimping and expansion process of the stent. Coating delamination at different regions of the stent was observed by scanning with electron microscope, and the force mechanism and influencing factors related with amorphous carbon coating delamination during stent crimping and expansion were analyzed by finite element method. Results The finite element results could perfectly agree with the experimental results. The thickness of amorphous carbon coatings determined the complexity, as well as the formation pattern of coating delamination at different regions of the stent. Larger elastic modulus of amorphous carbon coatings could cause the formation of coating delamination much easier to occur. Besides, the stent modulus would also have some impact with different influencing patterns at different regions on coating delamination. Conclusions In order to avoid coating delamination, the thickness of amorphous carbon coatings should be carefully designed, and the elastic modulus of both amorphous carbon coatings and stents should be rationally selected.