In-situ high-strain-rate (HSR) characterization of brain tissues via laser-induced cavitation helps to understand cavity-related mechanical characteristics of brain tissues. However, high optical diffusion and large mechanical complexity of the actual brain tissues, originating from their hierarchical and heterogeneous microstructures, hinder the introduction of the conventional laser-induced cavitation. To overcome the challenges, we demonstrate a two-dimensional seeded laser induced cavitation (2D-SLIC) approach, in which a mouse brain is sectioned to reduce the optical path length to 200 µm or less, and the sliced tissue is confined, with ablation seeds, between two glass plates. During the rapid deformation of the tissue specimen (>200 m/s) induced by SLIC, the local microscopic features are captured without image distortion using a femtosecond light source. As a result, since the digital image correlation (DIC) technique can be applied to the in-situ 2D-SLIC image with a reference (or pre-SLIC) image, the in-situ mapping of displacement vectors of the rapidly deforming brain slice can be achieved. Orientation mapping is used to investigate the anisotropic characteristics of brain tissue in different regions. The demonstrated mapping capability will be applied to investigate HSR dynamics dependent on specific locations (gray/white matter, cortex, striatum, hippocampus, etc.) within the brain.
2021-04-07 08:00:00
