The Engineer – Octopus suckers inspire grip of robotic suction cup

Based at Bristol Robotics Laboratory, the team studied the structures of octopus suckers whose adaptive suction abilities enable them to cling to rock. The team’s research is detailed in PNAS.

In their findings, the researchers show how they were able to create a multi-layer soft structure and an artificial fluidic system to mimic the musculature and mucus structures of biological suckers.

According to the university, suction is a highly evolved biological adhesion strategy for soft-body organisms to achieve strong grasping on various objects. Biological suckers can adaptively attach to dry complex surfaces including rocks and shells, which are challenging for current artificial suction cups.

Although the adaptive suction of biological suckers is believed to be the result of their soft body’s mechanical deformation, some studies imply that highly viscous in-sucker mucus secretion may be another critical factor in helping attach to complex surfaces.

In a statement, lead author Tianqi Yue said: “The most important development is that we successfully demonstrated the effectiveness of the combination of mechanical conformation – the use of soft materials to conform to surface shape, and liquid seal – the spread of water onto the contacting surface for improving the suction adaptability on complex surfaces. This may also be the secret behind biological organisms’ ability to achieve adaptive suction.”

Their multi-scale suction mechanism is an organic combination of mechanical conformation and regulated water seal. Multi-layer soft materials first generate a rough mechanical conformation to the substrate, reducing leaking apertures to micrometres. The remaining micron-sized apertures are then sealed by regulated water secretion from an artificial fluidic system based on the physical model, helping the suction cup achieve long suction longevity on diverse surfaces with minimal overflow.

Tianqi said: “We believe the presented multi-scale adaptive suction mechanism is a powerful new adaptive suction strategy which may be instrumental in the development of versatile soft adhesion.

”Current industrial solutions use always-on air pumps to actively generate the suction however, these are noisy and waste energy.

“With no need for a pump, it is well known that many natural organisms with suckers, including octopuses, some fishes such as suckerfish and remoras, leeches, gastropods and echinoderms, can maintain their superb adaptive suction on complex surfaces by exploiting their soft body structures.”

The findings are claimed to have potential for industrial applications, such as providing a next-generation robotic gripper for grasping irregular objects.

The team now plans to build a more intelligent suction cup by embedding sensors into it to regulate its behaviour.