Dimitriadis Emilios K, Horkay Ferenc, Maresca Julia, Kachar Bechara, Chadwick Richard S
Division of Bioengineering and Physical Science, Office of Research Services, Office of the Director, National Institute of Deafness and Other Communication Disorders, National Institutes of Health, Bethesda, MD 20892 USA.
Biophys J. 2002 May;82(5):2798-810. doi: 10.1016/S0006-3495(02)75620-8.
We address three problems that limit the use of the atomic force microscope when measuring elastic moduli of soft materials at microscopic scales. The first concerns the use of sharp cantilever tips, which typically induce local strains that far exceed the linear material regime. We show that this problem can be alleviated by using microspheres as probes, and we establish the criteria for their use. The second relates to the common use of the Hertz contact mechanics model, which leads to significant errors when applied to thin samples. We develop novel, simple to use corrections to apply for such cases. Samples that are either bonded or not bonded to a rigid substrate are considered. The third problem concerns the difficulty in establishing when contact occurs on a soft material. We obtain error estimates for the elastic modulus resulting from such uncertainty and discuss the sensitivity of the estimation methods to error in contact point. The theoretical and experimental results are compared to macroscopic measurements on poly(vinyl-alcohol) gels.
我们解决了在微观尺度下测量软材料弹性模量时限制原子力显微镜使用的三个问题。第一个问题涉及尖锐悬臂尖端的使用，这种尖端通常会引起远远超出材料线性范围的局部应变。我们表明，使用微球作为探针可以缓解这个问题，并确立了使用微球的标准。第二个问题与赫兹接触力学模型的普遍使用有关，该模型应用于薄样品时会导致显著误差。我们针对此类情况开发了新颖且易于使用的修正方法。考虑了与刚性基底 bonded 或未 bonded 的样品。第三个问题涉及确定何时与软材料发生接触的困难。我们获得了由这种不确定性导致的弹性模量误差估计，并讨论了估计方法对接触点误差的敏感性。将理论和实验结果与聚乙烯醇凝胶的宏观测量结果进行了比较。 （注：bonded 在这里不太明确准确中文意思，可能是“粘结”之类的意思，需结合更专业背景确定）
