Lightweight and High-Performance Ankle Braces Enabled by 3D Printed Metamaterial Liquid Crystal Polymer

Abstract

Ankle sprains significantly affect individuals’ mobility and functional ability. Ankle braces can provide external mechanical support around joints to prevent injurious ankle inversions. However, existing braces are often bulky and rigid, resulting in discomfort and restricted mobility for device users. Herein, a flexible, lightweight, and customizable ankle brace is proposed, with high performance that is achieved via 3D-printed liquid crystal polymer (LCP) mechanical metamaterials, leveraging molecular alignment and architected geometry to achieve programmable transition points between low- and high-stiffness behavior. Biomechanical simulations, optimization, and design of experiments are conducted to validate the proposed brace design and to evaluate the brace performance under high-risk scenarios. The effectiveness of the 3D-printed ankle braces is assessed in a gait lab using optical motion capture. Results showed that the 3D-printed brace provided the same level of protection as an off-the-shelf lace-up brace against sudden ankle inversion motions while not restricting natural ankle movements during walking. Compared to the off-the-shelf brace, the weight and thickness of the LCP-based brace are noticeably reduced. Similar structures coordinating macro and molecular-scale structures via 3D printing can be applied to other orthoses and medical devices generally, improving the quality of life for individuals with musculoskeletal injuries and other conditions.