EPFL developes gripper for delicate objects
EPFL scientists have developed a new soft robotic gripper that uses electroadhesion – flexible electrode flaps that act like a thumb-index gripper. It can pick up fragile objects of arbitrary shape and stiffness, like an egg, a water balloon or paper.
“This is the first time that electroadhesion and soft robotics have been combined to grasp objects,” says Jun Shintake, doctoral student at EPFL and first author of the publication.
When the voltage is turned on, the electrodes bend towards 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 their own weight and no prior knowledge about the object’s shape is necessary.
In comparison, other soft grippers are either pneumatically controlled or fail at picking up fragile objects unless the gripper has been told 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,” says PhD co-supervisor Dario Floreano of EPFL. PhD co-supervisor Herbert Shea adds: “Our unique configuration of electrodes and silicone membranes is what allows us to control the bending of the flaps and the electrostatic grip.”
The electrode flaps consist of five layers: a pre-stretched elastomer layer sandwiched between two layers of electrodes, plus two outer layers of silicone of different thickness. When the voltage is off, the difference in thickness of the outer layers makes the flaps curl outwards. When the voltage is on, the attraction between the two layers of electrodes straightens out the membranes. This straightening of the membranes from a curled position mimics muscle flexion.
At the tips of the flaps, the electrodes of each layer are designed for optimal electrostatic grip. These interdigitated electrodes, which look like two combs fitted together, create an electrostatic field that causes electroadhesion.
Visit the EPFL website for more information.
