Direct measurement of nonuniform large deformations in soft tissues during uniaxial extension.
Direct measurement of nonuniform large deformations in soft tissues during uniaxial extension.
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DOI：
10.1115/1.3116155
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发表时间：
2009-06
期刊：
影响因子：
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通讯作者：
T. Doehring;Michael Kahelin;I. Vesely
中科院分区：
文献类型：
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作者：
T. Doehring;Michael Kahelin;I. Vesely
了解微观结构组织和宏观力学功能之间的复杂关系是我们了解正常，患病/受伤和愈合结缔组织之间差异的基础。功能性组织工程构建物或支架的长期成功可能在很大程度上取决于我们对原始组织的结构组织的理解。尽管已经使用了创新技术来表征和测量胶原纤维的微观结构特性，但是在我们对中间尺度（即，“中间结构”）的纤维束组。本研究的目的是开发一个系统，能够直接测量这些较小的细观结构的变形过程中施加的控制载荷。一种新的细观结构测试系统（MSTS）已被开发应用控制多轴载荷中等（中）规模的组织标本，同时直接测量局部不均匀变形，使用同步数字视频捕捉和“无标记”的图像相关。MSTS的一个新组件是使用椭圆偏振光来增强胶原纤维对比度，为局部纤维变形的精确无标记特征跟踪提供必要的纹理。在本报告中，我们描述了系统的组件、校准和确认以及两种不同组织的结果：猪主动脉瓣尖和牛心包。对制备样品的验证试验表明，直接应变测量的最大误差为0.3%。在拉伸试验期间，发现主动脉瓣样本的不均匀应变大于牛心包。瓣膜样本的夹紧效应更为明显。一个新的系统，直接内部应变测量在结缔组织中的应用过程中的控制负载已经开发和验证。两种不同组织的结果表明，即使在简单的拉伸试验中，也会发生显著的不均匀变形。
Understanding the complex relationships between microstructural organization and macromechanical function is fundamental to our knowledge of the differences between normal, diseased/injured, and healing connective tissues. The long-term success of functional tissue-engineered constructs or scaffolds may largely depend on our understanding of the structural organization of the original tissue. Although innovative techniques have been used to characterize and measure the microstructural properties of collagen fibers, a large gap remains in our knowledge of the behavior of intermediate scale (i.e., "mesostructural") groups of fiber bundles in larger tissue samples. The objective of this study was to develop a system capable of directly measuring deformations of these smaller mesostructures during application of controlled loads. A novel mesostructural testing system (MSTS) has been developed to apply controlled multiaxial loads to medium (meso-) scale tissue specimens, while directly measuring local nonuniform deformations using synchronized digital video capture and "markerless" image correlation. A novel component of the MSTS is the use of elliptically polarized light to enhance collagen fiber contrast, providing the necessary texture for accurate markerless feature tracking of local fiber deformations. In this report we describe the components of the system, its calibration and validation, and the results from two different tissues: the porcine aortic valve cusp and the bovine pericardium. Validation tests on prepared samples showed maximum error of direct strain measurement to be 0.3%. Aortic valve specimens were found to have larger inhomogeneous strains during tensile testing than bovine pericardium. Clamping effects were more pronounced for the valve specimens. A new system for direct internal strain measurement in connective tissues during application of controlled loads has been developed and validated. The results from the two different tissues show that significant inhomogeneous deformations can occur even in simple tensile testing experiments.