Three-dimensional full-field measurements of large deformations in soft materials using confocal microscopy and digital volume correlation
Three-dimensional full-field measurements of large deformations in soft materials using confocal microscopy and digital volume correlation
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DOI：
10.1007/s11340-007-9037-9
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发表时间：
2007-06-01
影响因子：
2.4
通讯作者：
Ravichandran, G.
中科院分区：
文献类型：
--
作者：
Franck, C.;Hong, S.;Ravichandran, G.
发展了一种用于测量光学透明软材料大变形的三维全场测量技术。该技术利用数字体积相关（DVC）算法跟踪使用荧光共聚焦显微镜获得的3-D图像内的子体积的运动。为了将应变测量能力扩展到大变形区域（> 5%），开发了拉伸相关算法并将其实施到基于快速傅立叶变换（FFT）的DVC算法中。拉伸相关算法使用对数坐标变换将拉伸相关问题转化为平移相关问题，假设旋转和剪切较小。通过静态和平移测试提供测量精度的估计。建议的测量技术被用来测量大变形的透明琼脂糖凝胶样品嵌入荧光颗粒单轴压缩。该技术也被用来测量在远场单轴压缩下的硬球夹杂附近的非均匀变形场。拉伸相关算法的引入大大提高了应变测量的精度，尤其是在大变形的情况下。此外，共焦图像的解卷积提高了光轴方向上的测量精度。这些结果表明，所提出的技术是非常适合于调查细胞-基质的机械相互作用，以及获得局部的软生物材料，包括组织在3-D的本构特性。
A three-dimensional (3-D) full-field measurement technique was developed for measuring large deformations in optically transparent soft materials. The technique utilizes a digital volume correlation (DVC) algorithm to track motions of subvolumes within 3-D images obtained using fluorescence confocal microscopy. In order to extend the strain measurement capability to the large deformation regime (> 5%), a stretch-correlation algorithm was developed and implemented into the Fast Fourier Transform (FFT)-based DVC algorithm. The stretch-correlation algorithm uses a logarithmic coordinate transformation to convert the stretch-correlation problem into a translational correlation problem under the assumption of small rotation and shear. Estimates of the measurement precision are provided by stationary and translation tests. The proposed measurement technique was used to measure large deformations in a transparent agarose gel sample embedded with fluorescent particles under uniaxial compression. The technique was also employed to measure non-uniform deformation fields near a hard spherical inclusion under far-field uniaxial compression. Introduction of the stretch-correlation algorithm greatly improved the strain measurement accuracy by providing better precision especially under large deformation. Also, the deconvolution of confocal images improved the accuracy of the measurement in the direction of the optical axis. These results shows that the proposed technique is well-suited for investigating cell-matrix mechanical interactions as well as for obtaining local constitutive properties of soft biological materials including tissues in 3-D.