Mechanics-guided design of inflatable heterogeneous shape memory polymer vascular stents

Abstract

Vascular stent implantation is an effective method for the treatment of artery stenosis, and shape memory polymer (SMP) stents have become a promising stent type because of their good biodegradability and self-expandable capacity. However, due to the limited driving force obtained by the material's spontaneous recovery deformation, the current SMP stents suffer from low actuation speed and low actuation force during deployment. Here, we present a new design concept of SMP stents by utilizing two well-arranged heterogeneous SMPs in the stent structure domain and replacing the solid section with a hollow one. The resulting stents can therefore be inflated to expand and realize high-force actuations through extrinsically controlled pressure. A theoretical model that incorporates key design parameters including geometrical parameters and material distribution parameters is developed and validated by the finite element analysis to understand the fundamental mechanics of the stents during deployment. Design guidelines based on the model are further established to guide the design of the stents with desired performance. With support from the new design concept and associated theoretical foundation, the stents proposed here are expected to find wide applications in the biomedical field.