Physics Colloquium: Structural origins of the mechanics and fracture properties of articular cartilage (Prof. Moumita Das, Rochester Institute of Technology)

Abstract: Articular cartilage (AC) is a soft tissue that provides a smooth cushion and distributes the mechanical load in joints. As a material, AC is remarkable. It is only a few millimeters thick, can bear up to ten times our body weight over 100-200 million loading cycles despite minimal regenerative capacity, and still avoids fracturing. The simultaneous strength, fracture resistance, and longevity of native AC remain unmatched in synthetic materials. Such properties are desperately needed for tissue engineering, tissue repair, and even soft robotics applications. I will discuss the structural origins of and microscopic mechanisms leading to AC’s exceptional mechanical properties using the framework of rigidity percolation theory and compare our predictions with experiments. Our results provide an understanding of the tissue depth-dependent mechanical properties and how tissue mechanics changes in response to changes in tissue composition during diseases such as osteoarthritis. This framework also offers insights into how structure, composition, and constitutive mechanical properties can be tuned to resist and blunt cracks in AC and cartilage-inspired soft materials. The flexibility in resulting material properties and ease of implementation can be harnessed to fabricate artificial tissue constructs with tunable mechanics. I will discuss results that are an important step towards achieving this future.

Speaker Bio: Das is a theoretical soft matter and biophysicist, and is an Associate Professor of Physics at the Rochester Institute of Technology. Her group’s research focuses on the interplay of mechanics, statistical mechanics, and geometry in structure- function properties of cells and tissues, supported by awards from the National Science Foundation, National Institutes of Health, Keck Foundation, Moore Foundation, and Research Corporation. Das is also an advocate for women and under-represented groups in Physics and is committed to increasing their participation and visibility in STEM. Das received her Ph.D. in Physics from the Indian Institute of Science, Bangalore, India, and did postdoctoral research at Harvard University, UCLA, and Vrije Universiteit Amsterdam in the Netherlands. She has been on the faculty at RIT since 2012.