Design and 3D printing of lower limb prosthetic socket with metamaterials for performance enhancement

Abstract Globally, there are over 15 million individuals with lower limb amputations. Traditional prosthetic sockets, limited by handcrafting technology, frequently lack an optimal fit with the residual limb, leading to residual limb pain, skin abrasion, and compensatory gait. This paper presents an innovative version of prosthetic socket to optimize pressure distribution on the residual limb and enhance amputee’s comfort by introducing the zero Poisson’s ratio metamaterials. First, the musculoskeletal model of the residual limb was constructed using computed tomography data and divided into pressure-tolerant and pressure-sensitive zones based on biomechanical principles. The zero Poisson’s ratio metamaterials were embedded in the patellar tendon region to reduce localized stress concentration. The prosthetic socket, structurally optimized through finite element analysis, was fabricated using 3D printing technology and validated via flexible pressure sensing and gait experiments. Simulation results showed that the zero Poisson’s ratio metamaterials reduced skin stress in the patellar tendon region from 97.84 kPa (biomechanically designed prosthetic socket) to 83.74 kPa, achieving a 14.4% reduction. Human experiments further demonstrated a 11.7% decrease in peak walking pressure (145 kPa to 128 kPa). Furthermore, the knee joint symmetry coefficient duringsquatting improved from 0.992 to 0.999 when comparing the original socket to the zero Poisson’s ratio metamaterials socket. This method provides an efficient and precise solution for personalized prosthetic socket design, with the potential to enhance the mobility of amputees.