The objectives of this research are to measure the direction-dependent, mechanical properties of fibrous soft materials, such as artificial tissue, muscle or white matter in the brain. The proposed approach is to use magnetic resonance imaging to visualize and measure the propagation of elastic waves in the material. The speed of wave propagation through a solid material depends on its stiffness, and in a fibrous material the stiffness depends on the direction of loading. By using magnetic resonance imaging to visualize shear waves, it is possible to estimate these mechanical properties without invasive procedures or destructive testing. This approach will be validated by applying it to measure mechanical properties of fibrin gels in which fiber alignment is produced by polymerizing the gel in a magnetic field. It will then be used to non-invasively characterize mechanical properties of the brain.
If successful, the benefits of the research will include an improved ability to model and simulate the behavior of fibrous materials. It will enable accurate computer simulations of the mechanisms of traumatic brain injury and improved understanding of injury mechanics. Since white matter in the brain is particularly sensitive to mechanical deformation, the ability to model it correctly is extremely important to the design of protective devices and the development of therapeutic approaches. In addition, the proposed research may lead to new methods to monitor the condition of muscle, tendon, brain, or artificial tissue. The engineered gels used in this project may also have medical applications as tissue surrogates or scaffolds for nerve growth. A broad benefit of the project is that high school and undergraduate engineering students will learn to apply state-of-the-art imaging methods to understand complex mechanical behavior of an important class of materials.
