Kirigami skins make a simple soft actuator crawl

TLDR

Bioinspired soft machines made of highly deformable materials enable innovative applications, but their locomotion usually requires multiple independently activated actuators. The study harnesses kirigami principles to significantly enhance the crawling capability of a soft actuator. The authors designed highly stretchable kirigami surfaces that use mechanical instabilities to transform flat sheets into 3D‑textured surfaces resembling snake skin. The transformation dramatically altered surface friction, and when wrapped around an extending soft actuator, the resulting directional friction enabled efficient crawling.

Abstract

Bioinspired soft machines made of highly deformable materials are enabling a variety of innovative applications, yet their locomotion typically requires several actuators that are independently activated. We harnessed kirigami principles to significantly enhance the crawling capability of a soft actuator. We designed highly stretchable kirigami surfaces in which mechanical instabilities induce a transformation from flat sheets to 3D-textured surfaces akin to the scaled skin of snakes. First, we showed that this transformation was accompanied by a dramatic change in the frictional properties of the surfaces. Then, we demonstrated that, when wrapped around an extending soft actuator, the buckling-induced directional frictional properties of these surfaces enabled the system to efficiently crawl.