Octopus suckers inspire new water-resistant adhesive patch


The suckers of an octopus have inspired the creation of a new adhesive patch that can stick to wet and dry surfaces.

After studying the anatomy of an octopus’ tentacle, the scientists made a patch created from flexible sheets of rubber covered in artificial suction cups.

The sticky patches could one day be used to create wound dressings that can easily be taken on and off and may even inspire a generation of Spiderman-style robots that can scale walls, according to researchers.

The suckers of an octopus have inspired the creation of a new adhesive patch that can stick to wet and dry surfaces (stock image of an octopus tentacle)

HOW DOES THE PATCH WORK? 

After studying the anatomy of an octopus’ tentacle, the scientists made a patch created from flexible sheets of rubber covered in tiny holes.

To create the adhesive, the scientists concentrated on recreating a dome-shaped bulge found at the bottom of the octopus’ suction patch.

The scientists suspected that the bumps that cover these bulges contribute to the cups’ sucking ability.

They created a patch made of layers of flexible rubber that were covered in micro-metre sized holes that acted as suckers.

Inside every hole, they added material that mimicked the bulges found on octopus suction cups.

The researchers found that adding bulges to the artificial suckers enhanced their ability to stick to wet surfaces.

This is because the suction cups work by using capillary action – the same forces that drag water upwards through kitchen towel.

As the suckers pull water towards themselves, they are able to to create a tight bind with wet surfaces. 

Many animals have evolved special methods to stick themselves to wet and dry surfaces.

Geckos make use use of microscopic brushes to cling to walls, while barnacles and oysters attach themselves to rocks using sticky glue.

But the octopus is unique in its ability to use specialised suction cups to quickly stick and unstick itself to surfaces.

The flexibility of the octopus’ suction cups, which help the animal to move gracefully across the sea floor, has inspired scientists to create a new adhesive.

‘It is challenging to develop adhesives that are simple to make and also perform well – and repeatedly – under both wet and dry conditions, while avoiding non-chemical contamination on the adhered surfaces,’ the scientists from Sungkyunkwan University in South Korea said in a research paper.

‘Here we present an artificial, biologically inspired, reversible wet/dry adhesion system that is based on the dome-like protuberances found in the suction cups of octopi.’

To create the adhesive, the scientists concentrated on recreating a dome-shaped bulge found at the bottom of the octopus’ suction patch.

The scientists suspected that the bumps that cover these bulges contribute to the cups’ sucking ability.

They created a patch made of layers of flexible rubber that were covered in micro-metre sized holes that acted as suckers.

Inside every hole, they added material that mimicked the bulges found on octopus suction cups.

The researchers found that adding bulges to the artificial suckers enhanced their ability to stick to wet surfaces.

This is because the suction cups work by using capillary action – the same forces that drag water upwards through kitchen towel.

Diagram showing octopus tentacles (a), a detailed view of a suction cup’s internal structure (b), an image of the octopus-inspired adhesive on skin (left) and under a microscope (right)

As the suckers pull water towards themselves, they are able to to create a tight bind with wet surfaces.

The suckers are also able to stick to dry surfaces using similar forces. 

‘This octopus-inspired system exhibits strong, reversible, highly repeatable adhesion to silicon wafers, glass, and rough skin surfaces under various conditions (dry, moist, under water and under oil),’ the researchers said.

Jonathan Wilker, a professor of material science who has written a review of the new research for the scientific journal Nature, told MailOnline the adhesive could be used to make robots that can scale walls.

He said: ‘To me, at least, this current system seems like it could be a super system to apply to robots that we might want to walk up walls and move their way into other such spots.’

Images showing the octopus-inspired adhesive patch in underwater (left) and ambient (right) conditions

Top shows how the artificial suction cups stick and bind themselves to a surface in three stages. Below is confocal microscope images showing how liquid is drawn into the upper chamber of the cup

He added the patches could be used to make more environmentally friendly everyday products. 

He said: ‘Most of our adhesives are permanent. Think about the glues holding together your cell phone, furniture, shoes, and phone books.

‘We cannot take apart the components at the end of product life for recycling. So into the landfill they go.

‘Adhesives, like the ones described in this paper, might find their way into any situation where temporary, rather than permanent bonding could be helpful.

From fancy things like biomedical devices holding together your tissues to more everyday uses like hanging a picture on the wall come to mind.’

Images showing the adhesive patch being attached and detached from a surface (a) and a graph showing how patches preloaded with a buffer are more affective at being sticky (b)

And the researchers hope the patch could one day be used as a wound dressing that could easily be taken on or off.

‘Our octopus-inspired adhesives might be useful when applied over skin or a wound,’ the researchers said.

‘To examine their adhesion to rough skin, we first fabricated patches and then measured the adhesion forces when they are pulled off or peeled off from pigskin.’

Scientists found the adhesive patch performed well in this test – and was most effective when first filled with a buffer solution.

The researchers also prepared a wound dressing to test on skin lesions on mice.

They found the adhesive patch enhanced the healing of skin in comparison with smooth rubber that lacked octopus-like suckers.