It’s very difficult to design and program robot grippers to handle delicate objects carefully, such as fresh eggs. Researchers at the Ecole Polytechnique Fédérale de Lausanne (EFPL) in Switzerland have come up with a new way to carefully grasp fragile objects by using electrostatic force.
The robot grippers developed by the Swiss researchers consist of bendable flaps with electrodes. When a voltage is applied to the electrodes, the flaps bend toward the object just like a thumb and finger. The ends of the electrode flaps act like fingertips and conform to the shape of the grasped object. The grip of the flaps on the object is reinforced by electrostatic force, allowing the object to be lifted by the robot hand. The electrode flaps can support up to 80 times their own weight, and the shape of the object does not need to be known in advance.
The electrode flaps are formed as a five-layer sandwich, consisting of a pre-stretched elastomer layer in the middle surrounded by electrode layers on both sides and silicon layers of different thickness on the outside of each electrode layer. When no voltage is applied to the electrodes, the thickness difference causes the flaps to curl outwards. When a voltage is applied, the flaps straighten out due to the electrostatic attraction between the electrodes. At the tips of the flaps the electrodes are interleaved to produce an electrostatic field, which causes the tips to stick to the grasped object by electro-adhesion.