Octopus suckers: The future of underwater adhesives

Researchers at Virginia Tech have developed an adhesive inspired by octopus suckers, capable of quickly gripping and releasing challenging underwater objects. 

This breakthrough, detailed in the journal Advanced Science, could potentially revolutionize underwater salvage, rescue operations, and even technological applications that require manipulating difficult objects in wet environments.

The development team, which was led by Professor Michael Bartlett, included undergraduate researchers Austin Via, Aldo Heredia, and Daniel Adjei, as well as first author Chanhong Lee.

Challenge of underwater adhesive 

The primary goal of the study was to overcome the longstanding challenge of creating an underwater adhesive that can both hold onto objects securely and release them instantly – just as an octopus can.

“I am fascinated with how an octopus in one moment can hold something strongly, then release it instantly. It does this underwater, on objects that are rough, curved, and irregular – that is quite a feat,” Bartlett said.

Unique anatomy of octopus suckers

To solve the challenge of gripping underwater, the team turned to the unique anatomy of an octopus’s sucker, particularly focusing on a structure called the infundibulum. 

This outer section of the sucker allows the octopus to grasp and manipulate objects with incredible precision and strength. 

By mimicking this structure, the researchers developed an adhesive featuring an elastic, curved stalk and an active, deformable membrane that changes shape to achieve adhesion across multiple surfaces.

Incredibly efficient adhesive

The octopus-inspired adhesive significantly improves adaptability. Its curved stalk can attach to large-scale curvatures while its deformable membrane accommodates smaller surface irregularities. 

This combination allows the adhesive to maintain a strong grip on objects that vary in texture, shape, and size. 

The result is an adhesive that is 1,000 times stronger when activated compared to its easy-release state.

Even more impressively, this switch between gripping and releasing occurs in about 30 milliseconds, making the adhesive incredibly efficient for rapid object manipulation.

Remarkable precision for grip and release 

The researchers demonstrated this adhesive’s capabilities across a range of surfaces and fluids. The tool provides a powerful way to grip and release slippery underwater objects, such as heavy rocks or soft, jelly-like beads, without the need for excessive force. 

Divers using this technology could snatch up objects quickly and with precision, a significant advancement for underwater operations.

One key demonstration of the adhesive’s abilities involved constructing an underwater cairn – a carefully balanced pile of rocks. These rocks varied in size, shape, and roughness, and required careful manipulation to stack without tipping over. 

The octopus-inspired adhesive allowed the researchers to grab and release the rocks with precision, mimicking how an octopus arranges objects in its environment.

Manipulating difficult objects underwater 

“These types of manipulations are performed by an octopus as they arrange objects around their den,” said Lee. “This demonstration highlights the ability of the octopus-inspired adhesive to precisely manipulate difficult underwater objects.”

The adhesive also proved durable in long-term tests. It maintained consistent attachment strength over 100 cycles and was able to hold a rough, curved rock underwater for more than seven days, releasing it on demand. 

This kind of performance is especially critical in salvage operations, where holding objects over extended periods is necessary before release.

Technology inspired by octopus suckers 

Bartlett and his team have previously developed the Octa-Glove, an octopus-inspired glove equipped with LIDAR sensors that detect nearby objects and use a similar adhesive to capture and release them. 

Described in Science Advances, the Octa-Glove allows for strong, gentle bonding to objects without the need for excessive force, making it ideal for rescue divers, underwater archaeologists, and health care workers needing to manipulate wet or underwater objects.

The new research could make this technology even more versatile. “We hope to utilize our new adhesive design to further improve Octa-Glove,” Bartlett said. “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.”

Potential applications in diverse fields 

This new adhesive technology holds immense promise not only for underwater work but also for a variety of fields that require the manipulation of difficult-to-grip materials. 

With its ability to quickly grip, hold, and release diverse objects – including those with smooth, rough, or curved surfaces – the octopus-inspired adhesive could be used in a variety of environments where traditional adhesives or mechanical grips fail. 

It offers potential applications in fields as diverse as underwater exploration, salvage, medical technology, and robotics.

With the ability to grip objects securely without relying on excessive pressure, the technology may also reduce the risk of damaging delicate materials – a significant advantage in fields like archaeology, where the recovery of fragile artifacts is crucial. 

The future of octopus-inspired adhesives 

The team’s future plans include scaling up their experimental circuits and embedding them in larger, more complex robots that can operate in challenging conditions, such as monitoring power plants or exploring underwater environments.

By mimicking nature’s design of octopus suckers, Bartlett’s team has taken another step toward creating more dexterous, adaptive, and powerful robots. 

As technology advances, the potential for these octopus-inspired adhesives to transform how we interact with the underwater world and beyond is increasingly clear.

The research was supported by the National Science Foundation through its Designing Materials to Revolutionize and Engineer our Future program. 

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