根據美國華爾街預估，支架市場將在未來幾年將呈現倍數成長，達到上百億美金的規模。而人體可降解支架更宣告下一個新醫療器材世代的來臨。本研究首先探討可降解生醫材料聚乳酸PLA(Poly lactide)於熱轉印時材料性質變化與製程參數的關聯性，以找出適合可降解薄膜支架製作的加工參數，並開發環形轉印設備及製造方法製作PLA可降解薄膜支架。
　　從熱轉印參數性質研究結果發現，PLA材料會隨熱壓溫度升高與熱壓時間增長造成硬度與楊氏係數增加，但也導致斷裂伸長率變低。分析結果指出此材料性質變化，與熱壓後造成PLA結晶度提高有關。實驗結果所得到的較佳熱轉印製程條件為轉印時間60 s及轉印溫度110 oC，此條件下材料之機械性質約為硬度值17.8 Hv、楊氏係數138.87 MPa、斷裂伸長率6.96 %。此製程條件有效降低材料結晶度及脆化，並將應用於後續以環形熱轉印技術製作可降解薄膜支架。
於可降解薄膜支架開發中，首先利用商用Computational fluid dynamics (CFD)，在有限體積法(Finite volume method, FVM)基礎下，模擬PLA材料於環形模具中模穴的填充行為特徵，了解各製程參數的影響，進而探討PLA管材厚度對於支架成品薄膜厚度的關係，找出較佳的薄膜支架製程參數。
本研究以自行開發之環形轉印系統成功製作出直徑10 mm、厚度0.7 mm及薄膜厚度為0.1 mm之可降解薄膜支架，由結果得知在轉印時間60 s、轉印溫度110 oC及轉印壓力0.45 MPa時具有最佳的成形性。由徑向壓力試驗結果顯示，本研究所製作的薄膜支架其機械特性與設計值相符合，並且比無薄膜支架具有更良好之抗壓強度。在疲勞分析中，經由測試指出本研究所製作支架可承受半年期以上之血管收縮擴張，初步驗證了置放於血管內之可行性。本研究開發之環形轉印製程，相較於傳統雷射切割支架，可有效地降低製程時間及費用，對於未來在血管和非血管的可降解支架製程及量產上，具有一定的貢獻及突破。

According to Wallstreet’s prediction, stent market will continue to grow rapidly and would reach billions of USD in the future. In addition, the biodegradable stent could be the main player of the next generation. In this research, Poly lactide (PLA) was firstly analyzed with the properties for varying parameter in the thermal imprint process. Suitable parameters were discussed for biodegradable stent manufacturing. Then, a circular imprint system was developed to fabricate the PLA biodegradable graft stent.
The thermal imprint results show if the imprint temperature or imprint time increases more, the mechanical properties may change significantly. The results show that this phenomenon mainly occurs due to the crystallization. However, the results show that if we control the imprint temperature 110 oC, imprint time 60 s, a good elongation at break 6.96 %, hardness 17.8 Hv and Young’s modulus 138.87 MPa will be obtained.
In addition, commercial computational fluid dynamics (CFD) software based on the finite volume method (FVM) was used for simulating the PLA filling behavior, graft thickness relations and optimizing the imprint process. Finally, PLA graft stents were fabricated using the circular imprint process, and the experimental results were compared with the simulation.
The developed circular imprint system has successfully been used to fabricate PLA graft stents with dimensions of outer diameter 10 mm and thickness 0.7 mm and the graft thickness 0.1 mm. The results show the stent structures can be full filled with the process parameters of imprint time 60 s, imprint temperature 110 oC and imprint pressure 0.45 MPa. The results also show that this graft stent has a great compressive strength compared to non-graft stent, and it can be endure the contraction of artery vessels for longer than half year. This circular imprint process can efficaciously reduce the processing time and cost comparing to laser cutting process which is used to fabricate biodegradable stents currently. This study contributes to the fabrication and mass production of vascular and non-vascular biodegradable stents.

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