Application of Polymer Nanocomposites in the Design of Prosthetic Sockets that Feature Auxetic Meta-Structures

Lower limb amputees, comprising the majority, rely heavily on prosthetic devices for mobility. However, conventional prosthetic sockets often create uneven pressure distributions on the residual limb, leading to localized pressure points that cause skin irritation, discomfort, and long-term tissue damage, ultimately contributing to prosthesis abandonment. This study investigates the application of auxetic meta-structures and polymer nanocomposites to improve prosthetic socket design by enhancing interface pressure distribution, reducing deflection, and improving energy dissipation. Three prosthetic socket designs featuring internal meta-structures, chiral (auxetic), reentrant hexagon (auxetic), and regular honeycomb (non-auxetic), were modeled in SolidWorks and analyzed using finite element analysis (FEA) in Ansys under single-leg stance loading conditions. Each socket was simulated using five materials: polypropylene, ultra-high molecular weight polyethylene (UHMWPE), polypropylene with 5% zinc oxide (ZnO), polypropylene with 5% titanium dioxide (TiO₂), and UHMWPE with 0.5% graphene nanoplatelets. The results demonstrated that auxetic chiral prosthetic sockets consistently exhibited a 44.6% reduction in average interfacial pressure compared to non-auxetic hexagon sockets. The chiral design also showed a more uniform pressure distribution and enhanced energy absorption. While nanoparticle inclusion generally leads to less favorable contact pressure profiles, it offers a promising strategy for tailoring socket stiffness. These findings highlight the benefits of integrating auxetic geometries and nanocomposite materials in socket design to enhance user comfort and minimize prosthesis rejection. Additive manufacturing enables the scalable production of such customized prosthetic sockets, offering a promising pathway to improve access and quality of life for individuals with limb loss.