摘要
本研究計劃之目的，主要在探討支架的全製程與其相關之體外驗證分析；同時利用新設計之支架結構，來了解其擴張及握合後行為的表現…等；再則利用有限元素法去了解支架軸向、徑向的回縮率及應力分佈狀況。吾人之研究設計，乃使用三維繪圖軟體建構支架之外觀尺寸圖，再以有限元素軟體ANSYS 模擬分析支架之力學行為，並補強原型支架的結構，使其達到最適化幾何設計。 在支架的幾何結構分析中，吾人發現了支架的結構對其握合與擴張行為之軸向回縮率的影響，且不同的幾何特性之改變，也影響了支架力的表現。在基本模型支架之最適化研究，是在其肋與肋之間，加上補強結構之設計；其補強結構之設計，對於縮小其徑向與軸向之變形量、增加整體的支持力表現與減少最大應力發生等，將可提供相當之貢獻。 支架的製造流程，包含了真空退火、車製與拋光、雷射切割、超音波酸洗、電解拋光處理…等關鍵程序。所以支架的材料選擇與結構設計，亦會影響其相關的製造參數，包含了後續的金屬覆蓋率、網孔大小、徑軸向回縮率和支撐效率…等。選擇最適化之雷射切割參數，將影響其切割後的表面品質；同時表面品質的好壞，又與電解拋光的前處理相關；所以超音波酸洗和真空熱處理控制，將影響其後續的電解拋光過程。超音波酸洗的優點，乃是提供潔淨和無毛刺的支架表面；而真空熱處理的優勢，在消除支架的內應力和還原材料之晶粒組織。在製造過程的說明，包含電解拋光的方法和程序控制；電解拋光和鈍化處理的過程，是在提升支架表面的鉻層含量與去除直角邊(產生圓角邊)，所以電解拋光效果的好壞，將影響其植入對人體的反應…等。最後，製作出符合體外測試要求的支架成品。 支架完成後的體外測試，包含握合與擴張測試、三點彎曲測試和體外血管追蹤測試等實驗；上述體外試驗之目的，主要在量測支架握合和擴張後的徑向回彈率、軸向縮短率、支架在握合狀態下之彎曲靭性及在血管內推送過程的力量值。 透過該研究工作，可幫助吾人了解一支新開發的支架，所須完成的相關工作，也可提升國內相關研究過程的完整性與整確性。其可作為進入臨床動物試驗與人體試驗之前導型研究方案，同時該研究結果與方法流程，也可保護被植入支架之病患與相關醫療人員之安全…等。 最後，敝人透過執行此支架研究計劃的過程，慢慢的建立起學術研究與廠商技術合作的平台，也讓國內醫療器材產業等級提升與製造技術向下紮根。
並列摘要
This study investigated the procedures involved in the manufacturing of stents, employed in-vitro reliability verification, and conducted mechanics simulations to derive the radial and axial retraction rates and stress distribution with stents following balloon expand and crimp behavior. We first employed 3D graphics software to design a prototype and analyzed the different structures of the prototype and the optimized design; we then imported into finite element software ANSYS to simulate the mechanical behavior of the stent. We analyzed the different structures of the prototype and the optimized design. It is hoped that the data obtained in this study will help to improve the mechanical performance of actual stents. Moreover, geometrical structures properties also have an impact on stent characteristics and strength. The collected data in this study verifies that the optimized design, which differs primarily in the reinforcement of the rib and structural design, facilitates a significant increase in the deformation in the radial and axial directions. In addition, the optimized design exhibits enhanced support and reduced maximum stress. The results of the optimized design provide a useful reference. Generally, the key procedures in the process of manufacturing stents include the design of the stent structure, the selection of materials, vacuum annealing, boring and polishing, laser cutting, ultrasonic acid pickling, and electrolytic polishing. A number of studies have investigated the interaction between various parameters such as surface area of the metal, mesh size, axial shortening rates, and support efficiency. Optimized design can ensure that thermal stress is not concentrated during the process of laser cutting and that optimal cutting parameters are employed. Research has also shown that in surface treatment, the selection of cleaning acid, temperature, and time control in the ultrasonic acid pickling process contribute to the removal of burrs and grease. After laser cutting, the elimination of internal stress and the restructuring of surface grains often require material adjustment and precise control of the heat treatment process to attain optimal results. In the stent machining processes of surface passivation and chromium enrichment, we analyzed the principle of electropolishing and investigated the influence of methods and procedures, the selection of polishing solution, electrode design, and the temperature, voltage, and time of polishing on the resulting effects. Finally, stent products that meet the requirements of in-vitro testing can be manufactured. Once the stent prototype was constructed, we performed in-vitro mechanical testing, including crimping and expansion tests, a three-point bending test, and an in-vitro vascular tracking test. The primary objective was to measure the radial recoil rate and longitudinal recoil rate of the stent as well as its bending of intravascular toughness and flexibility. This study outlines the processes involved in the development of a new type of stent. It is hoped that these results can contribute to the integrity and accuracy of associated studies in the future, including research preceding clinical animal testing and human trials, protection of patients during implantation procedures, and safe operation by medical personnel.