A material inspired by the physics of geckos’ fingertips could allow robotic hands to grip nearly any type of object without applying excessive pressure. David Christensen, a mechanical engineering graduate student at Stanford University, was trimming a piece of adhesive modeled after the grippy fingers of geckos and noticed that the thin scrap seemed particularly grippy. He shared this observation with his colleague Elliot Hawkes, a Stanford doctoral candidate in mechanical engineering, who laminated a piece of nonstretchable, but very flexible, film to the back of the scrap. They found that the combination greatly magnified the grip, and also allowed some surprising properties. They anticipate a wide range of applications, including prosthetics, around-the-home robotics, or even industrial uses.
“The first time we played with the composite, it was clear the material grabbed onto textures that we were never able to grip before, but doesn’t remain stuck,” said Christensen.
They shared the material with a fellow graduate student, and they immediately realized that its ability to grip tightly to any textured surface, yet also release without effort, would make it ideal for a robotic grabber they were working on. The trio collaborated with others and ultimately designed a gripping mechanism that is able to pick up objects of many sizes, shapes, or textures-from trash bins to balloons to burritos-without having to squeeze them.
“What makes this gripper different is that it doesn’t need to squeeze objects to pick them up, since the material grips without pressing it into the surface,” Hawkes said.
It’s the first such system that does not rely on any sort of pressing force (like a person grabbing with a hand) or pulling force (like a suction cup or sticky tape). It manages this by mimicking the tiny hairs on gecko toes, the physics of which allow the animals to crawl on almost any surface. In this case, the underside of the fabricated material consists of thousands of tiny hairs, each only 100 microns long. When the hairs stand upright, they make contact with objects, but don’t grab onto them. As the gripping mechanism tugs on the film-like material, however, it wraps around the object, and the hairs flatten and touch the object. Altogether, the hairs exert a tremendous gripping force on the object. But simply release the tension on the film, and the hairs stand up again, making the material nonsticky and releasing the object.
The group now aims to build the material into a more complete robotic hand, and plan a particular focus on handling delicate objects.
This story was adapted from materials provided by Stanford University.