Study On 3D Printing Technology For Biodegradable Polymer Stent

Biodegradable polymer stents,as an important medical instrument in interventional therapy,have a good application prospect due to its biodegradability and good biocompatibility.At present,the main problems of biodegradable polymer stents are insufficient supporting performance,high manufacturing cost and long manufacturing cycle.In this paper,it's aimed to explore the feasibility of using fused deposition molding 3D printing technology to manufacture biodegradable polymer stents.Design and develop a four-axes 3D printing system,and investigate the influence of 3D printing operation conditions on dimensional accuracy,supportability and flexibility of the stent.The specific research contents are as follows:Firstly,to solve the problem of insufficient supporting performance of polymer stent,a polymer stent structure with dislocation distribution of struts was designed.Struts are composed of two closed curves at the apex,and the adjacent struts are distributed in dislocation to enhance the supporting performance.The supporting performance of the stent was verified by plate compression experiment,and the expanding process of the stent was analyzed by finite element method.The results show that the stent has good supporting performance and good expanding performance.Secondly,aiming at the typical hollow tubular structure of the stent,a four-axis 3D printing system was designed and developed.This printing system is based on the principle of fused deposition molding.On the basic of traditional Cartesian coordinate system FDM-based 3D printing system,a rotation axis with controllable motion is added as a new 3D printing platform for manufacturing stents.And as a support during the stent forming process,fused polymer material is deposited directly during printing a stent.The corresponding control system is designed to ensure that the printing system can manufacture the stent according to the stent model accurately.This four-axis 3D printing system has realized manufacturing stents efficiently and precisely.Finally,in order to obtain polymer stents with higher dimensional accuracy,better supporting performance and flexibility,the influence of printing process parameters on the above performance parameters of stents was studied.It had been investigated that the effects of operating conditions including printing temperature,printing speed,and step distance on the dimensions of strut and bridge,supporting performance and flexibility according to single factor experiment.And orthogonal experiments were designed to explore the significance of each processing parameters to related performance parameters of stent and the combination of processing parameters with better dimensional accuracy.The results show that the above processing parameters all affect the dimensional accuracy,supporting performance and flexibility of the stent.And stents can manufacture with good dimensional accuracy with the printing temperature of 220?,the printing speed of 12mm/s and the step distance of 0.15 mm.