ME: Jacob Notbohm
Friday,
February 21, 2020
11:00 AM - 12:00 PM
When cells contract or migrate within a three-dimensional fibrous matrix, they pull on the fibers surrounding them, generating displacements in the fibrous network. Though it is known that fibrous materials deform primarily by bending of fibers, the implications of fiber bending on the mechanics of the network are not fully clear. This is especially true for forces applied at small length scales, such as tens of microns typical of the size of a cell. This presentation will describe experiments and theoretical modeling to study the mechanics of fibrous materials at length scales of a cell.
Our experiments reveal that displacements propagate over a longer range than predicted by classical linear theory. Using a combination of experiments and theoretical modeling, we show that the long range displacements result from the fact that the fibrous structure has little resistance to compression. The experimental data also show that the random fibrous structure generates local displacements and local stiffness that are heterogeneous over space.
Our theoretical modeling suggests that the fibrous structure produces length-scale dependence, with stiffness being greater at smaller length scales. The length-scale dependence conflicts with classical elasticity, but it is consistent with theories such as Cosserat elasticity that account for local rotation of points. These findings share the common features that they result from collective bending of individual fibers and they occur at length scales similar to the size of a cell. Experiments are ongoing to connect these findings to how cells sense the mechanics of the surrounding fibrous matrix.
Our experiments reveal that displacements propagate over a longer range than predicted by classical linear theory. Using a combination of experiments and theoretical modeling, we show that the long range displacements result from the fact that the fibrous structure has little resistance to compression. The experimental data also show that the random fibrous structure generates local displacements and local stiffness that are heterogeneous over space.
Our theoretical modeling suggests that the fibrous structure produces length-scale dependence, with stiffness being greater at smaller length scales. The length-scale dependence conflicts with classical elasticity, but it is consistent with theories such as Cosserat elasticity that account for local rotation of points. These findings share the common features that they result from collective bending of individual fibers and they occur at length scales similar to the size of a cell. Experiments are ongoing to connect these findings to how cells sense the mechanics of the surrounding fibrous matrix.
Jacob Notbohm is an assistant professor in the Department of Engineering Physics at the University of Wisconsin-Madison. After receiving his Ph.D. from the California Institute of Technology in Mechanical Engineering in 2013 with Prof. G. Ravi Ravichandran, he worked as a postdoctoral researcher with Prof. Jeff Fredberg at the Harvard Chan School of Public Health.
Notbohm studies mechanical properties of biological materials and how physical interactions between cells and their surroundings control cell contraction and migration. The focus of this research is on mechanics with an emphasis on experiments. Notbohm has received multiple awards, including a Harvey D. Spangler named assistant professorship, a 3M Non-Tenured Faculty Award, and an NSF CAREER Award.
Notbohm studies mechanical properties of biological materials and how physical interactions between cells and their surroundings control cell contraction and migration. The focus of this research is on mechanics with an emphasis on experiments. Notbohm has received multiple awards, including a Harvey D. Spangler named assistant professorship, a 3M Non-Tenured Faculty Award, and an NSF CAREER Award.
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