| 摘要: | 在組織工程(Tissue Engineering)中，生物支架(Scaffold)的孔隙率(Porosity)對於細胞附著(Adhesion)、增殖(Proliferation)、營養物質傳輸以及代謝廢物的排出具有決定性影響，進而左右組織再生的成效。為精準建構具特定孔隙結構之生物支架，近年來廣泛採用三維生物列印(3D Bioprinting)技術進行製作。然而，在支架列印過程中，各列印層之轉角區域常因材料於轉角處沉積不均而產生幾何缺陷，使得層層堆疊成形後，支架內部孔洞易發生封閉或變形現象，進而降低整體孔隙率，最終對細胞存活與組織再生能力造成不利影響。
為了改善上述轉角沉積缺陷，本研究針對擠出式生物列印(Extrusion-based Bioprint-ing, EBP) 中採用低溫沉積製造(Low-Temperature Deposition Manufacturing, LDM)，且以殼聚醣(Chitosan) 為列印材料之製程，提出材料沉積變速率控制策略。該策略根據15°、30°、45°、60°與75°等不同角度的銳角轉角，透過同步調整列印速度與材料擠出壓力等兩項關鍵參數，用以精確控制材料在轉角區域的沉積速率。接著，利用影像處理(Image Processing)技術對於轉角區域的面積進行量化分析，並建立轉角列印品質分數(Corner Printing Score)以評估列印結果的優劣。
為了驗證所提出的策略，本研究列印了含有22.5°、37.5°、52.5°、67.5°與82.5°的多邊形支架。結果顯示該策略對於轉角過度擠料(Overfill)或擠料不足(Underfill)的問題均有一定程度的改善。此外，針對生物列印常見的90°曲折(Zigzag)支架，也分別比較了加速等壓與等速降壓等僅對單一參數調整的策略。從實驗結果發現，前兩者改善效果有限，而本研究提出之沉積變速率控制策略則可獲得更佳的轉角列印品質。綜上所述，本研究所提出的沉積變速率控制策略，能有效改善轉角區域的材料沉積缺陷，對於轉角缺陷的解決提供了一套可行的控制策略。
;In the tissue engineering, scaffold porosity is a critical determinant of cell adhesion, proliferation, and the efficient exchange of nutrients and metabolic wastes, directly influencing tissue regen-eration outcomes. While 3D bioprinting enables the fabrication of precise pore architectures, material accumulation at layer corners often results in geometric defects. This uneven deposition can lead to pore occlusion or deformation during layer-by-layer stacking, significantly reducing overall porosity and subsequently compromising cell viability and the capacity for tissue regen-eration.
To address this issue, this study proposes a variable material deposition rate control strategy for extrusion-based bioprinting (EBP) using a low-temperature deposition manufacturing (LDM) process with chitosan as the printing material. The proposed method simultaneously adjusts the printing speed and extrusion pressure according to different corner angles (15°, 30°, 45°, 60°, and 75°) to precisely regulate material deposition in corner regions. Image processing tech-niques were employed to quantify the deposited area, and the corner printing score was estab-lished to evaluate printing performance.
Experimental results from polygonal scaffolds (22.5°–82.5°) demonstrate that the proposed strategy effectively reduces overfill and underfill defects. In addition, for the commonly used 90° zigzag scaffold, compared with single-parameter control methods such as acceleration with constant-pressure and constant-velocity with reduced-pressure, the proposed approach achieved superior corner printing quality.
Overall, the developed control strategy provides a feasible and practical method for im-proving corner deposition quality in 3D bioprinting scaffolds. |
