SMA for Energy Constraint in an Absorbable Implant

Partially absorbable composite filaments are bench tested to determine their corrosion and mechanical suitability for vascular implant service.  The status quo is that metallic vascular implants are produced from corrosion-resistant metals such as Co-Ni-Cr, 316L and Nitinol.  The next decade should bring commercialization of structures which return to a more natural and physiological state by completely dissolving or morphing to provide a mechanical match to local anatomy.  Nitinol, in particular, plays a key role in peripheral vascular stenting, where extreme displacement and point element strain are crucial to device survival and function.  Corrosion-fatigue of fully absorbable implants and associated sequelae are a significant hurdle for absorbable technology.  Here, a centrally-integrated shape memory alloy filament is used in a braided construct in order to provide superelastic constraint of an otherwise absorbable metal scaffold.  Composite filaments are produced using absorbable iron-manganese (FeMn) with encapsulated Nitinol filaments.  The initially stiff tubular braided specimens are shown to maintain target geometry throughout the course of dissolution of the FeMn component, leaving behind a structure 600 to 1000 times more compliant compared to the “non-absorbed” structure.