In the bottom-up approach, Highly Auxetic Yarn (HAY) was fabricated using a custom 3D-printed rig to helically wrap stiff fishing line around an elastic cord core [1]. Instron testing of a single- and double-loop prototypes revealed Young’s moduli of 0.514 MPa and 0.432 MPa, respectively, indicating that the single-loop configuration provided enhanced auxetic performance and elasticity. Cotton yarns of varying lengths were also characterized as potential elastic cores for future auxetic systems.
In the top-down approach, auxetic geometries were laser-cut into cotton fabric using the FabAcademy bistable auxetic model [2], producing samples that demonstrate visible lateral expansion under tension while maintaining flexibility. Cotton was chosen for its accessibility, versatility, and potential for functionalization with active compounds, enabling the development of adaptive, medicated textiles.
Collectively, these fabrication methods, yarn-based and fabric-based, provide low-cost, reproducible pathways for producing flexible auxetic materials suitable for therapeutic wraps and patches. Future work will focus on optimizing auxetic geometries, quantifying Poisson’s ratios, and exploring chemical functionalization to incorporate active compounds for skin applications. This study establishes a foundation for accessible auxetic textiles with potential impact in personalized biomedical and wearable technologies.
References:
[1] Bhattacharya, S.; Zhang, G. H.; Ghita, O.; Evans, K. E. The Variation in Poisson’s Ratio Caused by Interactions between Core and Wrap in Helical Composite Auxetic Yarns. Composites Science and Technology 2014, 102, 87–93. https://doi.org/10.1016/j.compscitech.2014.07.023.
[2] Fab14 Workshop. fabacademy.org. https://fabacademy.org/2018/labs/fablabulb/FAB14_workshop_bistable.html.