MULTISCALE MECHANICS AT BIOLOGICAL INTERFACES
Washington University in St. Louis, USA NSF Center for Engineering MechanoBiology, USA
The effective interfacing of dissimilar materials is a key challenge in physiology, surgical repair, and engineering structures. A central issue at such interfaces is the point at which a phase of or a cell population within soft, active biological tissues reaches a percolation threshold. We believe that a number of physically based pathologies are associated with the approach to percolation. The talk will begin with a broad summary of pathologies of percolation, and proceed to detail our group’s work on the attachment of tendon to bone. Here, the healthy body presents a smooth gradient in mineralization but a non-monotonic gradient in stiffness to ameliorate high stresses at the bi-material interface. Neither healing nor surgery recreates this attachment, possibly explaining the relatively high rates of reinjury experienced by patients with rotator cuff tears. We describe key toughening and strengthening mechanisms, and describe how these can be reconstituted in surgical grafts and repair.