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Characterization of the mechanical properties of soft materials: Acute rat brain tissue and hydrogel.

机译：柔软材料的机械性能表征：急性大鼠脑组织和水凝胶。

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摘要

The biomechanics of the brain in reaction to injury, surgery, or disease is dependent on bulk mechanical properties of central nervous system tissues. Accurately measured mechanical properties can be used to predict structural changes and determine internal stresses within brain tissues subjected to various environmental forces. Previous studies have characterized mechanical behavior of brain tissues over large brain regions or have classified tissue properties for either gray or white matter regions only. Therefore, they are limited in their ability to explain complex deformations due to interactions between different anatomical regions. Moreover, loss of cell viability and morphological change of tissue which could potentially affect the changes of mechanical properties were not critically considered. This study provides a fundamental methodology for characterizing local mechanical properties of ex vivo, thin brain tissue slices and soft, hydrated biomaterials.;Firstly, two different microindentation systems, Hysitron nanoindentation and optically-based indentation systems, were introduced to measure mechanical behaviors in local regions of thin brain tissue slices and soft hydrated biomaterials. The Hysitron nanoindentation system allowed measurement of local mechanical behavior with various testing modes and an optically-based micro indentation system was introduced for mechanical testing of even softer materials over long time periods. Secondly, FE models were developed to estimate accurate mechanical properties, while considering a finite thickness effect, large deformation and complex geometry. Biphasic FE models were introduced to estimate mechanical and transport properties, hyperviscoelastic FE models were used to estimate viscoelastic parameters and equilibrium modulus over long time periods. Finally, histology methods were developed to detect a loss of cell viability and changes of tissue integrity.;Overall, a methodology for indentation tests was developed to improve mechanical properties measurements of acute brain tissue slices and soft hydrated biomaterials. With the combination of developed methodologies, this study provides more accurately measured mechanical properties in brain tissue and takes into consideration 1) spatial changes in different anatomical regions, 2) temporal changes during the loading period and 3) biological changes due to tissue degradation. Additionally, this technique may be used to characterize the mechanical behavior of other thin tissue slices and biomaterials.
机译：对损伤，手术或疾病作出反应的大脑生物力学取决于中枢神经系统组织的整体机械特性。准确测量的机械性能可用于预测结构变化并确定承受各种环境力的脑组织内部的内应力。先前的研究已经表征了大脑组织在较大大脑区域上的机械行为，或者仅对灰色或白色物质区域进行了分类。因此，由于不同解剖区域之间的相互作用，它们解释复杂变形的能力受到限制。此外，没有严格考虑可能会影响机械性能变化的细胞活力丧失和组织形态变化。这项研究为表征离体，薄脑组织切片和柔软的水合生物材料的局部机械性能提供了基本的方法。首先，引入了两种不同的微压痕系统，即Hysitron纳米压痕和基于光学的压痕系统，用于测量局部的机械行为薄的脑组织切片和柔软的水合生物材料区域。 Hysitron纳米压痕系统允许使用各种测试模式测量局部机械行为，并且引入了基于光学的微压痕系统，可对更长的软材料进行长时间的机械测试。其次，开发了有限元模型来估计精确的机械性能，同时考虑了有限的厚度效应，大变形和复杂的几何形状。引入了双相有限元模型来估计机械性能和传输性能，使用高粘弹性有限元模型来估计长时间内的粘弹性参数和平衡模量。最后，开发了组织学方法以检测细胞活力的丧失和组织完整性的变化。总体而言，开发了压痕测试方法以改善急性脑组织切片和软化水合生物材料的力学性能测量。结合已开发的方法，这项研究可以更精确地测量脑组织的机械性能，并考虑到1）不同解剖区域的空间变化，2）加载期间的时间变化以及3）由于组织退化引起的生物学变化。另外，该技术可用于表征其他薄组织切片和生物材料的机械性能。

著录项

  • 作者

    Lee, Sung Jin.;

  • 作者单位

    University of Florida.;

  • 授予单位 University of Florida.;
  • 学科 Engineering Biomedical.;Biophysics Biomechanics.;Engineering Mechanical.
  • 学位 Ph.D.
  • 年度 2011
  • 页码 141 p.
  • 总页数 141
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

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