A seamless auxetic substrate with a negative Poisson’s ratio of −1
Yung Lee, Bongkyun Jang, Hyunggwi Song, Sumin Kim, Yong Won Kwon, Hyun Seok Kang, Min Seong Kim, Inkyu Park, Taek‐Soo Kim, Junho Jang, Jae‐Hyun Kim, Jang‐Ung Park, Byeong‐Soo Bae
Abstract
Auxetic metamaterials are a unique class of materials or structures with a negative Poisson’s ratio and a wide array of functionalities. However, their inherent porosity presents challenges in practical applications. Filling the inherent perforations while preserving their unique auxeticity is difficult because it demands the seamless integration of components that have highly distinct mechanical characteristics. Here we introduce a seamless auxetic substrate film capable of achieving a negative Poisson’s ratio of −1, the theoretical limit of isotropic materials. This breakthrough is realized by incorporating a highly rigid auxetic structure reinforced by glass-fabric, with surface-flattening soft elastomers. We effectively optimize the mechanical properties of these components by systematic experimental and theoretical investigations into the effects of relative differences in the moduli of the constituents. Using the developed auxetic film we demonstrate an image distortion-free display having 25 PPI resolution of micro-LEDs that is capable of 25% stretching without performance degradation. The inherent porosity of auxetic metamaterials challenge their applicability. Here, the authors introduce a seamless auxetic substrate film capable of achieving a negative Poisson’s ratio of −1 incorporating a rigid auxetic structure reinforced by glass-fabric, with surface-flattening soft elastomers applied as an image distortion-free display.