Azeloglu Evren U, Kaushik Gaurav, Costa Kevin D
Department of Biomedical Engineering, Columbia University, USA.
Annu Int Conf IEEE Eng Med Biol Soc. 2009;2009:4273-6. doi: 10.1109/IEMBS.2009.5334043.
Standard analysis methods for atomic force microscope (AFM) indentation experiments use Hertzian contact mechanics to extract local elastic properties assuming a homogeneous sample material. In contrast, most biological materials have heterogeneous structure and composition. We previously introduced a non-Hertzian analysis method to detect depth-dependent elastic properties from indentation depth, force and geometry information. In this study we employ a modified Eshelby model to characterize the elastic properties of heterogeneous substrates with discrete embedded inclusions. In this hybrid computational model, we estimate the contribution of inclusions with known size and moduli to the overall indentation response of a heterogeneous substrate based on the effective volume fraction of constituents within the indentation field. For wide ranges of indenter size and inclusion geometry, simulations reveal a consistent ellipsoidal indentation field, suggesting the Eshelby model may be applicable for large discrete inclusions. This novel technique provides a potential means to calculate inclusion properties of heterogeneous materials, such as cells and tissues, using AFM indentation without physical deconstruction of the composite sample.
原子力显微镜（AFM）压痕实验的标准分析方法采用赫兹接触力学，在假设样品材料均匀的情况下提取局部弹性特性。相比之下，大多数生物材料具有异质的结构和组成。我们之前引入了一种非赫兹分析方法，可根据压痕深度、力和几何信息检测与深度相关的弹性特性。在本研究中，我们采用修正的埃舍尔比模型来表征具有离散嵌入内含物的异质基底的弹性特性。在这个混合计算模型中，我们基于压痕场内成分的有效体积分数，估算已知尺寸和模量的内含物对异质基底整体压痕响应的贡献。对于各种压头尺寸和内含物几何形状，模拟显示出一致的椭圆形压痕场，这表明埃舍尔比模型可能适用于大型离散内含物。这项新技术提供了一种潜在方法，可利用AFM压痕计算异质材料（如细胞和组织）的内含物特性，而无需对复合样品进行物理解构。
