It was just a few weeks ago that we heard how scientists from the University of Washington had developed a highly-effective suction cup inspired by the humble clingfish. Well, researchers at the University of California-San Diego have taken a different approach to create one of their own, and they've even used it on an underwater robot.
The northern clingfish inhabits the rough waters of the ocean's intertidal zone, living up to its name by clinging to rocks in order to keep from being swept away. It does so utilizing two fins on the underside of its body, which combine to form a disc that can adhere even to rough surfaces.
Both the Washington and San Diego teams noted that there are layers of tiny hair-like structures around the edge of that disc, which allow it to form a seal against a variety of surfaces by creating friction. Additionally, the disc is very flexible and elastic, boosting its ability to maintain contact.
Both teams thus proceeded to copy this structure in a series of prototype suction cups, which performed very well at sticking to and then lifting a variety of heavy, rough-surfaced objects.
One of several ways in which the UC San Diego cup differs, however, is that it incorporates bio-inspired slits in its silicone rim. These help the material conform to the contours of irregularly-shaped surfaces.
"The incorporation of slits in the disc margin was inspired by the intersection of the pelvic and pectoral fins of the clingfish," lead author and PhD student Jessica Sandoval tells us. "We demonstrated the ability of our prototypes to attach to delicate objects, such as produce, crabs, conch shells, and vases."
Sandoval pilots underwater ROVs (remotely-operated vehicles), and was therefore also interested in seeing how the technology could be applied to them.
"With ROVs, we collect delicate specimens, from organisms such as clams to archeological artifacts, such as amphoras, from the sea floor," she says. "Thus, we need to be able to grip delicately and reliably. To demonstrate the use case of the suction disc, we used our prototype to pick and place raw eggs, a feat for us as pilots as it is quite difficult to grasp such a fragile object with the aluminum jaws of a manipulator."
A paper on the research was recently published in the journal Bioinspiration and Biomimetics.
Source: UC San Diego