The project was born out of Stanford engineering professor Mark Cutkosky’s Biomimetics and Dextrous Manipulation Lab, which has been focused on creating bio-inspired robots for about 30 years. Some of its best-known inventions are the sticky, gecko-like robots that climb walls and grab onto space junk. But in this instance, “sticky,” is not the same kind of sticky as a substance like duct tape, which leaves a gummy residue. When Cutkosky says “sticky,” he’s referring to a drier, rubberier kind of sticky that takes advantage of the attractions between tiny molecules courtesy of van der Waals forces.
Instead of being all metal all the way through, this robot hand has semi-squishy fingertips, and each finger pad surface is made from a film of gecko adhesive supported by a rubber bone-like structure underneath. Cutkosky imagines that with hands like these, one day the device could perform more intricate tasks, like picking and handling heirloom tomatoes.
In the animal world, actual gecko fingers have microscopic features: little wedge-like stalks that taper into tiny, spatula-like tips. “When you pull them the right way, they all lie down sideways, and it goes from having hardly any contact area to having almost continuous contact area,” says Cutkosky. “That large area of contact is what allows van der Waal’s forces to produce adhesion.”
The gecko adhesive that his lab made, which looks like a strip of plastic, is a simplified imitation of what real life gecko fingers can do. Unlike tape, the artificial gecko adhesive only sticks onto a surface if you pull in a certain way—otherwise it will fall off. That’s because when the adhesive is lying on a surface, only the very tips of the wedges are touching it, and there’s hardly any contact area. But when the strip is pulled sideways, those wedges all lie down, increasing the contact area.
“It works well for climbing,” says Cutkosky. “We had been thinking for years how we might be able to use it for more down-to-Earth applications like grasping with a robot hand.”
Source : https://www.popsci.com/technology/stanford-robot-hand-with-gecko-adhesives/
