Collaborative Research: Micro- and Nano-Scale Characterization and Modeling of Bone Tissue

该项目的研究目的是表征骨组织的微观力学行为。骨是一种具有层次结构的材料，其组织级别从纳米到毫米不等。成分和微观结构随年龄和疾病而变化。迄今为止，关于骨骼力学特性的大部分工作都集中在宏观尺度上（例如毫米厘米尺度），而对构成骨骼构件的矿化组织的内在力学特性知之甚少。该研究项目通过应用微加工技术分离特定的微结构部件来表征这些特性，然后在简单的压缩中进行测试。利用飞秒激光烧蚀和聚焦离子束微加工技术制造出尺寸从数百纳米到数十微米不等的微柱，然后使用改进的纳米压头进行测试。力学测试的结果将用于开发骨折的微观力学模型。该研究项目的结果将为组织的微观和纳米级力学特性建立一种实验方法，其力学功能对肌肉骨骼健康至关重要。这些方法将通过提供一种方法来确定这些变化如何在与变化本身相同的长度尺度上影响骨力学性能，从而补充现有的研究年龄和疾病相关的骨成分和微观结构变化的技术。该研究项目还将重点关注青年科学家和工程师的专业准备。本科生和研究生将直接参与研究活动。研究活动还将纳入课程和推广活动，使大学预科学生和非技术学生接触材料科学和工程领域。

The research objective of this project is to characterize the microscale mechanical behavior of bone tissue. Bone is a hierarchically structured material with organization levels ranging in size from nanometers to millimeters. Composition and microstructure vary with age and disease. The majority of work to date on mechanical characterization of bone has focused on macroscale properties (e.g. millimeter-centimeter scale), and little is known about the intrinsic mechanical properties of the mineralized tissue that constitutes the building block of bones. This research project characterizes these properties by applying micromachining techniques to isolate specific microstructural components, which are then tested in simple compression. Micropillars ranging in size from hundreds of nanometers to tens of microns are produced by femtosecond laser ablation and focused ion beam micromachining techniques and then tested using a modified nanoindenter. The results of the mechanical tests will be used to develop micromechanical models of bone fracture. The results of this research project will establish an experimental approach for micro- and nanoscale mechanical characterization of a tissue whose mechanical function is critical for musculoskeletal health. These methods will complement existing techniques for studying age- and disease-related changes in bone composition and microstructure by providing a means of determining how these changes affect bone mechanical properties at the same length scale as the changes themselves. This research project will also focus on professional preparation of young scientists and engineers. Undergraduate and graduate students will participate directly in the research activities. The research activities will also be incorporated in courses and outreach events that expose pre-college and non-technical students to the field of materials science and engineering.