- 學位論文
應用張拉整體機構於細胞計算力學研究
Application of Tensegrity Mechanisms for Computational Investigation of Cell Mechanics
摘要
由於機械力學性質為生物細胞固有之物理特性，對於細胞形態方面之運動、遷徙、分裂與增殖過程等機械力傳導過程十分重要，於各細胞生理研究領域中，細胞力學性質常用以做為性質指標，應用於不同齡期階段細胞的發育變化、正常與病態細胞的區分與細胞於微組織環境特定條件設定等，而綜觀此研究領域，細胞內部生物與化學反應於整體機械性質對應機制之解析尚少。 有鑑於人體肌肉組織和骨骼系統之幾何與分佈特徵，肌肉組織的張力連結，可強化了相連於肌肉組織且多處於壓力狀態的骨骼系統功能，形成了一個相互支撐型態的力學機械系統；緣此，基於細胞結構型態，本論文研究以張拉整體機構建立細胞力學模型，以特殊之離散元件組成型式，用以評估微環境外力引致細胞變形過程，不同的力與變形響應曲線代表了不同的細胞機械特性，以表徵其力學特性，並與實驗影像與測試結果相映；且於張拉整體機構中，組成準則為：受力構件僅受到純拉或壓之軸力，主要分佈於輪廓之受拉構件構成了細胞外型，主要分佈於內部之受壓構件間無相互接觸，在系統應力逐漸增大下，各構件始終能保持原有受拉與受壓之變形狀態，因而具有優良的系統穩定性。計算方面，以有限元素法進行數值分析，當中使用非線性材料組成進行細胞骨架材料之非線性設定，並運用迭代法求解出機構模型對於外部載荷之響應，以模擬細胞骨架纖維之受拉與受壓力量傳遞。重要的是，為了驗證模型機械性質計算結果，本論文並蒐集了大量研究文獻，在不同細胞微環境與生理情況中，將細胞張拉整體機構模型與文獻實驗影像進行對照，並比較細胞機械性質之量測數據，且以張拉整體模型分析所得整體切線模量與應變之相關曲線，可用以說明細胞剛性因纖維結構改變而變化的趨勢。 論文內容方面：第二章為張拉整體研究動機與應用，並詳述細胞骨架主要構成元件；第三章介紹張拉整體機構設計對於整體剛性的影響，並包含相關有限元素法理論與實作；第四章詳細比對研究文獻之細胞骨架實驗影像，基於影像量測之纖維數量與分佈以及纖維束寬度來建立張拉整體機構模型，並可將模型所求出不同變形程度之切線模量與文獻相應實驗數據比較，進行一系列的模型驗證；第五章為結論及未來研究展望。
並列摘要
Since mechanistic properties are inherent physical characteristics of biological cells, they are important for the mechanical force transmission processes such as cell morphology, migration, division and proliferation, etc. In cell physiology research, cellular mechanical properties are often used as property indicators for cell developmental changes at different age stages, differentiation of normal and diseased cells, and setting of specific conditions of cells in microenvironment. However, in this field of research, the mechanism of internal biological and chemical reactions of cells in response to the overall mechanical properties has not yet been analyzed. In view of the geometric and distributional characteristics of human muscle tissue and skeletal system, the tensional linkage of muscle tissue can strengthen the function of skeletal system which is connected to muscle tissue and is mostly under pressure, forming a mutually supportive mechanics system. Therefore, based on the type of cellular structures, this thesis investigates the cellular mechanics modeled by tensegrity mechanisms, with a special discrete component composition, to evaluate the cellular deformation process caused by microenvironmental loading. The tensioned members mainly distributed along the boundaries form the cell shape, and the compressed members mainly distributed in the bulk part have no mutual contact with each other. Under gradual increase of system stress, each member can always maintain its original deformation state of tension and compression, thus having excellent system stability. The computational analysis was performed by the finite element method, in which the nonlinear material composition was used for the cytoskeletal materials, and the response of the tensegrity model to external loading was solved by the iterative method. In order to verify the mechanical properties of the model, a large number of research papers were collected in this thesis, and the overall cellular tensegrity models were compared with the experimental images in different cell microenvironments and physiological conditions, and the measured data sets of the cell mechanical properties were also investigated. The thesis is organized as follows: Chapter 2 presents the research motivations. Chapter 3 introduces the theory and implementation of the finite element method. Chapter 4 investigates the experimental images of the cytoskeleton in detail, and compares the tangential modulus of different degrees of deformation obtained from the cellular tensegrity models with the corresponding experimental data sets for validation. Finally, Chapter 5 shows the conclusion and future research outlook.