Researchers have developed a new and improved snake-inspired soft robot that is faster and more precise than its predecessor.

Programmable kirigami metamaterials enable responsive surfaces and smart skins. (Image: Harvard SEAS)

The robot is made using kirigami — a Japanese paper craft that relies on cuts to change the properties of a material. As the robot stretches, the kirigami surface “pops up” into a 3D-textured surface that grips the ground just like snake skin.

The first-generation robot used a flat kirigami sheet that transformed uniformly when stretched. The new robot has a programmable shell, meaning the kirigami cuts can pop up as desired, improving the robot’s speed and accuracy. In flat kirigami, the pop-up is continuous, meaning everything pops at once. But in the kirigami shell, pop-up is discontinuous. This kind of control of the shape transformation could be used to design responsive surfaces and smart skins with on-demand changes in their texture and morphology.

The new research combined two properties of the material: the size of the cuts and the curvature of the sheet. By controlling these features, the researchers were able to program dynamic propagation of pop-ups from one end to another or control localized pop-ups.

In previous research, a flat kirigami sheet was wrapped around an elastomer actuator. In this research, the kirigami surface is rolled into a cylinder, with an actuator applying force at two ends. If the cuts are a consistent size, the deformation propagates from one end of the cylinder to the other; however, if the size of the cuts is chosen carefully, the skin can be programmed to deform at desired sequences.

By borrowing ideas from phase-transforming materials and applying them to kirigami-inspired architected materials, the researchers demonstrated that both popped and unpopped phases can coexist at the same time on the cylinder. By simply combining cuts and curvature, remarkably different behavior can be programmed.

Watch a video demo on Tech Briefs TV here. For more information, contact Leah Burrows at This email address is being protected from spambots. You need JavaScript enabled to view it.; 617-496-1351.

Motion Design Magazine

This article first appeared in the June, 2019 issue of Motion Design Magazine.

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