Octopuses have a superpower. They can cling to nearly any surface, no matter how wet or slippery, with their sucker-lined tentacles. Now, scientists at Virginia Tech have tapped into this ability to create a new type of adhesive that could revolutionize underwater rescue, robotic gripping, and even delicate surgeries.

The inspiration came from the octopus’s remarkable suction cups, which allow it to grip everything from smooth rocks to soft marine creatures.

During tests, the adhesive easily grabbed and released stones, soft beads, shells, and other heavy, soft, rough, curved, and slippery objects, with weights ranging from 2.5 grams to 870 grams. It’s a fascinating breakthrough that could bring us closer to using octopus-like technology in the real world.

“Underwater environments present a long list of challenges, and this advance gets us over another hurdle. We’re now closer than ever to replicating the incredible ability of an octopus to grip and manipulate objects with precision, opening up new possibilities for exploration and manipulation of wet or underwater environments,” Michael Bartlett, study co-author and an associate professor at Virginia Tech, said.

Science behind the octopus-inspired adhesive

To understand how the adhesive works, it’s important to first know how octopus tentacles function. Octopus tentacles are lined with numerous suction cups. On the inside, each of these cups contains flexible, muscular rings called the infundibulum. These rings work together with the acetabulum, the larger central cavity of the suction cup, to create powerful suction. 

So when an octopus attaches its tentacle to an object, the infundibulum molds to the shape of the object, forming a tight seal. This enables the octopus to hold onto even slippery or uneven surfaces with impressive strength.

The Virginia Tech team mirrored this design in their adhesive, using a curved rubber stalk and a silicone membrane to replicate the action of the suction cups.

When the air pressure is lowered, the stalk deflates, causing the membrane to pull in and grab onto objects, just like an octopus. To release the object, the pressure is increased, inflating the stalk and loosening the grip. This design allows the adhesive to grab onto a wide range of surfaces with ease, from slippery and soft materials to rough, irregular objects.

“The combination of a curved stalk allows us to create contact on challenging surfaces. The membrane, which we use to turn the suction on and off, now allows us to manipulate a very diverse range of objects,” Bartlett said.

The researchers claim that their adhesive membrane has a 1,000 times stronger gripping force when its stalk is deflated compared to when it’s inflated. Plus it can switch between grab and release modes within 30 milliseconds, making it a very practical solution for real-world applications.

“With this new tool, a diver could hold a slippery object without applying excessive squeezing, also being able to snatch it quickly with rapid switching,” the researchers added.

Testing the grip of the adhesive

In lab tests, the adhesive performed spectacularly. It was able to grip everything from heavy stones to delicate jelly-like beads, maintaining its strength over hundreds of cycles. Even after 100 cycles of gripping and releasing, its power didn’t wane. In one case, the adhesive held onto a 452-gram rock underwater for seven days straight before releasing it on demand.

The adhesive has been integrated into Octa-glove, an innovative glove designed to replicate the gripping action of octopus tentacles. It features flexible fingers and suction cups that enhance a wearer’s ability to grasp objects, even those that are slippery or uneven. This innovation was developed by Bartlett and his colleagues in 2022. 

Bartlett and his team hope the adhesive will make the Octa-glove even more versatile, opening the door to other octopus-inspired inventions.

The study is published in the journal Advanced Science.