Rigid–soft hybrid knitted origami structures with stiffness-tunable panels and programmed folding directions

Abstract

Computerized flat knitting offers advantages in programmability, integrative forming, and multi-material integration. Here, we present rigid–soft hybrid knitted origami structures that combine stiffness-tunable spacer panels with soft folding lines of predefined curling direction, all fabricated in a single knitting process. This design addresses a key limitation of conventional knitted foldable structures, in which the high compliance of loop-based fabrics allows deformation to spread beyond the intended crease regions. The panels are reinforced with spacer fabrics to suppress unintended bending, and their bending stiffness can be tuned through knitting parameters. The soft folding lines, by contrast, curl intrinsically toward either a mountain or a valley fold, with the curling direction programmed by switching stitch formation between the front and back needle beds. Using these two mechanisms, we develop seven fundamental foldable units as modular building blocks for more complex origami structures and demonstrate them in three prototypes: a vacuum-driven folding actuator, a Kresling-inspired adjustable lampshade, and a Miura-inspired foldable structure. The Miura structure deploys to 60 × 40 × 0.5 cm and folds to 38 × 20 × 5 cm, showing compact shape transformation and preliminary qualitative stability under static loading. This strategy provides a scalable route to programmable foldable knitted fabrics for adaptive structures, soft robotics, and functional architecture.