Inspired by natural snapping systems like Venus flytrap leaves and hummingbird beaks, physicists at the University of Massachusetts have given a fast, programmable snapping motion to thin curved shells using curved creases.
The technique developed by physicist Christian Santangelo and his team avoids the need for complicated materials and fabrication methods during the creation of structures with fast dynamics. The research outlines the geometry of folding a creased shell and demonstrates the conditions under which it may fold smoothly.
Until now there has been no general geometric design rule for creating a snap between stable states of arbitrarily curved surfaces. Thanks to the new development, material scientists and engineers can now design structures that can rapidly switch shape and properties. “This gives us a way of using geometry to design ultrafast, mechanical switches that can be used, for example, in robots,” Santangelo said.
Although a lot of plants and animals take advantage of elasticity to move rapidly, researchers haven’t really known how to use this in artificial devices.
The team intoned that in spite of the simultaneous coupling of bending and stretching of a shell naturally giving items great stability for engineering applications, folding curved surfaces can be a herculean task.
They further added that the new technique would find application in designing structures over a wide range of length scales, including self-folding materials, tunable optics and switchable frictional surfaces for microfluidics, which are used in inkjet printer heads and lab-on-a-chip technology.
The team claims that until now shape programmable structures used origami to reconfigure using a smooth folding motion, but were hampered by slow speeds and complicated material assembly. However their new fast snapping motion could overcome these hindrances, marking a major step in generating programmable materials with rapid actuation capabilities.
Image courtesy of University of Massachusetts Amherst