Photobleaching as a tool to measure the local strain field in fibrous membranes of connective tissues
Résumé
Connective tissues are complex structures which contain collagen and elastin fibers. These fiber based structures have a great influence on material mechanical properties and need to be studied at the microscopic scale. Several microscopy techniques have been developed in order to image such microstructures; among them are two-photon excited fluorescence microscopy and second harmonic generation. These observations have been coupled with mechanical characterization to link microstructure kinematic to macroscopic material parameter evolution. In this study, we present a new approach to measure lo cal strain in soft biological tissues using a side effect of fluorescence microscopy: photobleaching. Controlling the loss of fluorescence induced by photobleaching, we create a pattern on our sample that we can monitor during mechanical loading. The image analysis allows computing 3D displacements of the patterns at various loading levels. Then, local strain distribution is derived using the finite element discretization on a four nodes element mesh created from our photobleached pattern. Photobleaching tests on human liver's capsule have revealed that this technique is non-destructive and has not any impact on mechanical properties. This method is likely to have other applications in biological material studies, considering that all collagen-elastin fibers based biological tissues possess autofluorescence properties, and thus can be photobleached.
Origine : Fichiers produits par l'(les) auteur(s)
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