Gao Xin, Gu Weiyong
Department of Mechanical and Aerospace Engineering, Tissue Biomechanics Laboratory, University of Miami, Coral Gables, FL, United States.
Department of Mechanical and Aerospace Engineering, Tissue Biomechanics Laboratory, University of Miami, Coral Gables, FL, United States; Department of Biomedical Engineering, University of Miami, Coral Gables, FL 33124-0624, United States.
J Biomech. 2014 Sep 22;47(12):3196-200. doi: 10.1016/j.jbiomech.2014.06.012. Epub 2014 Jun 21.
It is challenging to noninvasively determine the mechanical properties of biological soft tissues in vivo. In this study, based on the biphasic theory and the transport models, a new constitutive model for hydration-dependent mechanical properties in hydrated soft materials was derived: HA = An(1-fϕ)(fϕ)2-n/2(2-fϕ), where HA(=λ+2 μ) is the aggregate modulus, ϕ(f) is the volume fraction of fluid (i.e., hydration), A and n (>2) are two parameters related to the transport properties of the biphasic materials. A linear model for hydration-dependent shear modulus in the literature was verified for hydrogels. The effects of tissue hydration on mechanical properties (aggregate modulus and Poisson's ratio) were investigated. It was found that the value of Poisson's ratio was very sensitive to the tissue hydration in soft materials with high water content. The predictions of the aggregate modulus and shear modulus for hydrogels by the model compared well with those from experimental results. This study is important for developing new techniques for noninvasively assessing the mechanical properties of biological soft tissues using quantitative MRI methods as well as for designing scaffolds with proper mechanical properties for tissue engineering applications.
在体内非侵入性地确定生物软组织的力学性能具有挑战性。在本研究中，基于双相理论和传输模型，推导了一种用于水合软材料中水合依赖性力学性能的新本构模型：HA = An(1 - fϕ)(fϕ)2 - n/2(2 - fϕ)，其中HA(=λ + 2μ)是总模量，ϕ(f)是流体的体积分数（即水合作用），A和n(>2)是与双相材料传输特性相关的两个参数。文献中关于水合依赖性剪切模量的线性模型在水凝胶中得到了验证。研究了组织水合对力学性能（总模量和泊松比）的影响。结果发现，在高含水量的软材料中，泊松比值对组织水合非常敏感。该模型对水凝胶总模量和剪切模量的预测与实验结果吻合良好。本研究对于开发使用定量MRI方法非侵入性评估生物软组织力学性能的新技术以及为组织工程应用设计具有适当力学性能的支架具有重要意义。
