From nature to mechanical metastructures: bioinspired architectures for transtibial prosthetic liners

Biological tissues achieve advanced mechanical performance through geometry-driven strategies such as hierarchy, graded porosity, anisotropy, and controlled non-linear deformation rather than homogeneous material properties. These principles have inspired the development of mechanical metastructures, whose effective behavior emerges primarily from architectural design. Recent advances in additive manufacturing have enabled the translation of such bioinspired architectures into wearable biomedical systems. This review analyses bioinspired mechanical metastructures with a specific focus on their applicability to transtibial prosthetic liners. Cellular and lattice-based architectures, auxetic structures, triply periodic minimal surfaces, hierarchical and multistable systems, and hybrid soft–stiff designs are examined in relation to key clinical requirements, including pressure redistribution, shear mitigation, energy absorption, and adaptability during gait. Experimental and numerical studies demonstrate that architected elastomeric metastructures can reproduce and locally tailor stiffness ranges comparable to commercial liners while significantly reducing peak stresses and improving deformation control. Despite remaining challenges related to durability, viscoelastic behavior, and clinical validation, bioinspired metastructures represent a promising pathway toward personalized, adaptive prosthetic liners with enhanced comfort, stability, and long-term residual-limb health.