Inverse origami inspired by insect morphogenesis: geometric design of wrinkle structures for curved surface formation
Insect exoskeletons abruptly acquire complex three-dimensional forms during metamorphosis from larva to pupa. This transformation occurs through the unfolding of preformed wrinkle structures inside the larval body under internal pressure. Inspired by this process, we investigate an inverse-origami strategy for fabricating curved surfaces. Whereas conventional origami produces three-dimensional objects by folding a flat sheet, this strategy produces curved surfaces by unfolding preformed wrinkle structures. The central design problem is to derive a wrinkle structure from a prescribed target surface. Our key idea is to regard a wrinkle structure as a unidirectional stretching field, which specifies at each point the stretch produced when the structure unfolds. We first derive such a field from the target surface geometry and then translate it into spatially varying wrinkle directions and spacing, so that the wrinkle structure unfolds into the target. The resulting numerical designs approximate the intrinsic metric of the target surface. We demonstrate the method on multiple target surfaces through numerical construction, mechanical unfolding simulations, and 3D-printed prototypes. This work provides a biologically inspired geometric design principle for encoding prescribed surface shapes in wrinkle structures, as well as a framework for designing and fabricating deployable curved surfaces.