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Robotic Fingers Use Static to Create Gentle Touch

Photograph of the robotic gripper by Alain Herzog, courtesy of EPFL.

Scientists at Switzerland’s Federal Institute of Technology in Lausanne (EPFL) have developed a lightweight, soft robotic gripper-made of rubber and stretchable electrodes-that can bend and pick up delicate objects of arbitrary sizes like eggs, paper, and water balloons. Possible uses for these robotic fingers include food handling for the food industry, capturing debris in outer space, or incorporation into prosthetic hands.

The electrostatic stickiness caused by rubbing a balloon on hair to make it stick to the wall is called electroadhesion. The soft gripper uses electroadhesion in the form of flexible, layered electrode flaps that act like a thumb-index gripper and are designed for optimal electrostatic grip. The interdigitated electrodes look like two combs fitted together. When the voltage is turned on, the electrodes bend toward the object to be picked up, imitating muscle function. The tip of the electrodes act like fingertips that gently conform to the shape of the object, gripping onto it with electrostatic forces in the same way that the balloon sticks to the wall. These electrodes can carry 80 times its own weight and no prior knowledge about the object’s shape is necessary. The research is featured in the January 13 issue of Advanced Materials.

“This is the first time that electroadhesion and soft robotics have been combined together to grasp objects,” said Jun Shintake, a doctoral student at EPFL and first author of the publication.
Other soft grippers are either pneumatically controlled or fail at picking up fragile objects without telling the gripper beforehand about the object’s shape. They also have been unable able to handle flat or deformable objects.

“The novelty of our soft gripper is the ideal combination of two technologies: artificial muscles and electroadhesion,” said study coauthor Dario Floreano, PhD, director of EPFL’s Laboratory of Intelligent Systems. “Our unique configuration of electrodes and silicone membranes is what allows us to control the bending of the flaps and the electrostatic grip.”

Editor’s note: This story is adapted from materials written by Hillary Sanctuary and provided by Federal Institute of Technology in Lausanne (EPFL).