Investigation of Crease Patterns in Infrared Light-Induced Self-Folding Origami

Self-folding origami using heat-shrink polymer sheets has attracted attention as a simple and low-cost method for constructing three-dimensional structures. However, in conventional approaches employing linear crease patterns, the self-folding angle of the heat-shrink sheet has generally been limited to approximately 130°, restricting the design flexibility of complex origami structures. In this study, we propose a novel cross-shaped crease pattern for infrared light-induced self-folding origami using a heat-shrink polystyrene sheet. Black ink patterns were printed on the surface of the heat-shrink sheet to locally absorb infrared light to generate thermal shrinkage of the sheet above its glass transition temperature. Comparisons between linear and cross-shaped crease patterns showed that the folding angle increased with the width and area of the patterned region. Notably, the cross-shaped crease pattern enabled significantly larger folding angles, reaching up to approximately 170°, compared to conventional linear patterns. Furthermore, for the same folding angle, the cross-shaped pattern achieved a smaller radius of curvature with a reduced patterned area of the printed black ink. These results demonstrate that two-dimensional control of shrinkage distribution around the crease is an effective strategy for enhancing folding performance and expanding the design freedom of three-dimensional self-folding origami structures.