Robotic gripper with a delicate touch

Engineering researchers from North Carolina State University have demonstrated flexible, robotic grippers that are able to lift delicate egg yolks without breaking them, and that are precise enough to lift a human hair. The work, published in Nature Communications, has applications for both soft robotics and biomedical technologies.

The grippers draw on the art of kirigami, which involves both cutting and folding two-dimensional (2D) sheets of material to form three-dimensional (3D) shapes. Specifically, the researchers have developed a new technique that involves using kirigami to convert 2D sheets into curved 3D structures by cutting parallel slits across much of the material. The final shape of the 3D structure is determined in large part by the outer boundary of the material. For example, a 2D material that has a circular boundary would form a spherical 3D shape.

Image credit: Jie Yin, North Carolina State University

“We have defined and demonstrated a model that allows users to work backwards,” said Yaoye Hong, first author of a paper on the work and a PhD student at NC State. “If users know what sort of curved, 3D structure they need, they can use our approach to determine the boundary shape and pattern of slits they need to use in the 2D material. And additional control of the final structure is made possible by controlling the direction in which the material is pushed or pulled.”

“Our technique is quite a bit simpler than previous techniques for converting 2D materials into curved 3D structures, and it allows designers to create a wide variety of customised structures from 2D materials,” said Jie Yin, corresponding author of the paper and an associate professor of mechanical and aerospace engineering at NC State.

The researchers demonstrated the utility of their technique by creating grippers capable of grabbing and lifting objects ranging from egg yolks to a human hair.

“We’ve shown that our technique can be used to create tools capable of grasping and moving even extremely fragile objects,” Yin said.

“Conventional grippers grasp an object firmly — they grab things by putting pressure on them,” Yin said. “That can pose problems when attempting to grip fragile objects, such as egg yolks. But our grippers essentially surround an object and then lift it — similar to the way we cup our hands around an object. This allows us to ‘grip’ and move even delicate objects, without sacrificing precision.”

There are a number of other potential applications, such as biomedical technologies that conform to the shape of a joint such as the human knee, which the researchers are now exploring.

Watch the video of the technology below:
 

Image credit: ©stock.adobe.com/au/Elena Moiseeva