Experiment and finite element analysis on amorphous carbon coatings delaminating from vascular stents / 医用生物力学

ABSTRACT

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.