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Kirigami-inspired gripper lifts fragile objects without breaking them

Kirigami-inspired gripper lift...
The gripper is both gentle and highly precise
The gripper is both gentle and highly precise
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The gripper is both gentle and highly precise
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The gripper is both gentle and highly precise

Most robotic grippers work by applying pressure to an object from either side – it's an approach which could damage delicate items. A new gripper gets around that problem, however, thanks to an ancient Japanese art form.

Related to the paper-folding art of origami, kirigami involves making a series of parallel slits in a flat sheet of material.

When that two-dimensional sheet is subsequently pulled apart, pushed inwards, twisted or otherwise manipulated, the slits cause it to buckle into a predetermined three-dimensional shape. In recent years, we've seen the art form utilized in everything from programmable balloons to robotic snakes to anti-slip shoe soles.

The 3D shape which a kirigami sheet takes on is determined not only by the slit patterns and the way in which it's manipulated, but also by the shape of the flat sheet. A disc-shaped sheet, for instance, will typically morph into a sphere.

Led by PhD student Yaoye Hong and Assoc. Prof. Jie Yin, a team at North Carolina State University has now developed a computer program that figures out what sheet shape, slit pattern and type of manipulation is required in order to end up with a specified 3D shape.

The scientists used the technology to create a flexible robotic gripper, the two sides of which slide together beneath a fragile object, meeting on its underside and surrounding it like a pair of cupped hands. Not only is the device gentle enough to lift an egg yolk without breaking it, but it's also precise enough to grasp and lift a human hair.

"This is proof-of-concept work that shows our technique works," said Yin. "We’re now in the process of integrating this technique into soft robotics technologies to address industrial challenges."

A paper on the research was recently published in the journal Nature Communications. The gripper is demonstrated in the following video.

kirigami grippers can grasp egg yolk and a human hair

Source: North Carolina State University

3 comments
3 comments
Username
It doesn't work because it's gentle, it works because it scoops.
Ralf Biernacki
What is the material they made the gripper of? The choice of material is as important as the cut pattern. It must be elastic enough to return to its original configuration once tension is taken off. But it must not be rubbery, or it would stretch rather than curl in the desired shape. It must be insensitive to stress concentration at notches, or it would tear at the cuts. It must be very resistant to crack propagation for the same reason---in fact, it should contain a mesh of randomly oriented fibers. Paper meets these requirements fairly well---but this clearly is /not/ paper, paper would not survive the wetting, especially of the cut edges. What is it?
Ralf Biernacki
What is the material they made the gripper of? The choice of material is as important as the cut pattern. It must be elastic enough to return to its original configuration once tension is taken off. But it must not be rubbery, or it would stretch rather than curl in the desired shape. It must be insensitive to stress concentration at notches, or it would tear at the cuts. It must be very resistant to crack propagation for the same reason---in fact, it should contain a mesh of randomly oriented fibers. Paper meets these requirements fairly well---but this clearly is /not/ paper, paper would not survive the wetting, especially of the cut edges. What is it?