Journal
JOURNAL OF THE MECHANICAL BEHAVIOR OF BIOMEDICAL MATERIALS
Volume 29, Issue -, Pages 138-150Publisher
ELSEVIER SCIENCE BV
DOI: 10.1016/j.jmbbm.2013.08.027
Keywords
Brain tissue damage; Confined compression; Solid-fluid interaction; Extracellular fluid; Models of injury; Permeability; Rat brain
Funding
- University of Maryland SEED grant
- Center for Energetics Concepts Development of the University of Maryland-College Park
Ask authors/readers for more resources
The mechanical processes that underlie mild traumatic brain injury from physical insults are not well understood. One aspect in particular that has not been examined is the tissue fluid, which is known to be critical in the mechanical function of other organs. To investigate the contributions of solid-fluid interactions to brain tissue mechanics, we performed confined compression tests, that force the extracellular fluid (ECF) to flow in the direction of the deformation, on 6.35 mm diameter, 3 mm long cylindrical samples excised from various regions of rat brains. Two types of tests in deformation control, (1) quasi-static, slow and moderate constant strain rate tests at 0.64 x 10(-5)/s, 0.001/s and 1/s to large strains and (2) several applications of slow linear deformation to 5% strain each followed by stress relaxation are employed to explore the solid-fluid interaction. At slow and moderate compressive strain rates, we observed stress peaks in the applied strain range at about 11%, whose magnitudes exhibited statistically significant dependence on strain rate. These data suggest that the ECF carries load until the tissue is sufficiently damaged to permit pathological fluid flow. Under the slow ramp rate in the ramp-relaxation cycles protocol, commonly used to estimate permeability, the stress relaxes to zero after the first cycle, rather than to a non-zero equilibrium stress corresponding to the applied strain, which further implicates mechanical damage. Magnetic resonance imaging (MRI) of changes in tissue microstructure during confined compression, before and after compression, provides further evidence of tissue damage. The solid-fluid interactions, reflected in the morphology of the stress-stretch curves and supported by the MRI data, suggest that increases in hydrostatic pressure in the ECF may contribute to mechanical damage of brain tissue. (C) 2013 Elsevier Ltd. All rights reserved.
Authors
I am an author on this paper
Click your name to claim this paper and add it to your profile.
Reviews
Recommended
No Data Available