Self-Folding Acute-Angle Origami Driven by Surface Bending Force

This study describes a self-folding origami technique that enables acute angle folding by surface bending force for the first time. We patterned plus-shaped “+” carbon black patterns on a shrinking sheet and achieved self-folding of the 2D sheet quite sharply (more than 160°) trigger with infrared (IR) light irradiation. We investigated the folding angle of our sheet with “+” pattern comparing to the sheet with slit pattern on a crease, and confirmed that our sheet could be folded at larger folding angle than the sheet with slit pattern. Next, we examined the folding angle of the sheet that had “+” pattern with different width and found that the folding angle increased when the surface bending force increased. Finally, we demonstrated this “+” pattern to fabricate 3D word objects “MEMS”. Our surface bending approach to Origami folding could open a new avenue to widen the variety and controllability of self-folding objects.