Watch How Soft Robotic Fingers Get a Grip With Gecko AdhesivesS. Himmelstein | April 13, 2018
The ability of the gecko to climb and cling to virtually any surface inspired Jet Propulsion Laboratory researchers to formulate an adhesive replicating the lizard’s grasping prowess. In a collaboration with engineers at the University of California San Diego, the synthetic material was applied to the fingers of a soft robotic gripper to impart a stronger grasping mechanism.
The gripper was shown to grasp objects in various positions and to handle pipes, mugs and other objects. The device also manipulated rough, porous and dirty objects, such as volcanic rocks — a task that is typically challenging for gecko adhesives — and picked up pieces of large, cylindrical pipe — a task typically difficult for soft robotic grippers.
The air-powered soft robotic gripper can lift up to 45 pounds and could be used to grasp objects in a range of settings, from factory floors to the International Space Station. An original master gecko adhesive mold with millions of microscopic structures is made in a clean room using a photolithography process. Wax copies of the master mold are then made at low cost, and the researchers can produce as many copies of the adhesive sheets from the wax mold as needed by using a spin coating process. This allows them to make 10 to 20 adhesive sheets in under an hour. The soft robotic gripper itself is cast in 3D print molds and is made of silicone-based rubber.
The researchers designed the gripper to apply the correct van der Waals forces along the entire length of the fingers. A high-strength fabric embedded in the finger helps to distribute force along the flexible gripper while maintaining the manufacturing precision required for the adhesives. The fabric easily bends but resists stretching to support larger loads. The fingers are rigidly clamped to a base, which keeps the easily stretchable silicone from deforming beyond what is needed. The resulting combination of soft and stiff materials lets the gripper conform to many objects while withstanding large forces.
The researchers will present their findings at the 2018 International Conference on Robotics and Automation May 21 to May 25 in Brisbane, Australia.