Functionally graded lattice structure sole with programmed cushioning for pronation correction

Overview

This solution introduces a 3D-printed shoe sole built from functionally graded lattice structures that deliver programmed cushioning tailored to correct the three different pronation types. By strategically placing combinations of auxetic and non-auxetic lattice geometries, the sole can provide differentiated energy absorption and mechanical response in specific zones, addressing the biomechanical needs of each wearer. The approach also accounts for the time-dependent permanent deformation that materials undergo during use, ensuring correction remains effective over the product's lifecycle.

The technology targets the footwear and orthotics market, offering a customizable, data-driven alternative to conventional uniform soles. It has potential applications in performance athletic footwear, medical orthotics, and personalized comfort products where targeted support and cushioning are critical.

Technical specifications

Core technology and design approach:

• Functionally graded lattice structures combining auxetic (negative Poisson's ratio) and non-auxetic geometries to achieve zone-specific cushioning and energy absorption
• Programmed cushioning mapped to pronation correction requirements, with lattice placement driven by pressure mapping data
• Material innovation using thermoplastic polyurethane (TPU) synthesized from clean-based polyols rather than fossil-derived polyols, supporting sustainability goals
• Mechanical characterization through uniaxial compression testing and simulation, validated using Doehlert Design combined with Response Surface Methodology for multi-response optimization
• Manufacturing flexibility demonstrated initially via Fused Filament Fabrication (FFF), with planned scale-up through Selective Laser Sintering (SLS) for higher-volume production
• Statistical modeling of compression response surfaces enabling predictive design of lattice configurations for specific cushioning profiles

Technology readiness level

The technology is currently at a mid-level readiness stage. Individual lattice structures have been 3D printed in TPU (Shore hardness 95A, comparable to conventional shoe sole materials) and physically tested under uniaxial compression alongside computational simulations. Results confirm that design parameters significantly influence the mechanical response, and response surface models have been generated.

Next-stage validation requires mapping foot pressure zones to determine where differentiated cushioning is needed, then combining this data with the established lattice response models to produce prototype soles. Current prototyping relies on a lab-scale EOS printer; the research team seeks access to industrial-scale 3D printing systems to validate the model at production-relevant scale. The complete validation study is estimated at 7 to 8 months. The team brings complementary expertise in computational mechanics, rheology, and 3D printing to advance the technology toward commercial readiness.