A new type of suction cup inspired by the octopus suction cup makes it easier and more energy-efficient for robots to lift and release objects with rough surfaces. The secret lies in using water to mimic octopus slime. Unlike most artificial suction cups, octopus suction cups have no problem forming a seal on objects with rough, curved, or irregular surfaces, such as rocks. For some time, it has been thought that this effect is almost entirely due to the softness and plasticity of the suction cup tissue.
However, Dr Yue Tianqi and colleagues at the University of Bristol wondered if the importance of the mucus secreted by these suction cups had been overlooked. To figure this out, they made an artificial octopus sucker.
The device has the same cup-shaped shape as a natural suction cup and consists mainly of multiple layers of overlapping soft silicone. This allows it to largely adapt to the contours of rough surfaces, like an octopus's sucker.
Still, there will be some micron-sized gaps between the device and the surface during initial contact. To fill these gaps, water needs to be injected through an attached tube. The liquid flows into a fluid system that forms a ring at the bottom of the cup, just as mucus cells form a ring at the bottom of an octopus sucker.
When water seeps out of tiny openings in the fluid system, it fills all the tiny gaps, creating a perfect seal. In this way, the glass can be lifted and held in place indefinitely.
Since the water in the tube is always under pressure, any small amount of water that leaks out is immediately replaced. When it's time to release an object, simply lift one side of the rim of the cup to break the seal.
"We believe that the proposed multi-scale adaptive suction mechanism is a powerful new adaptive suction strategy that may contribute to the development of versatile soft bonding technologies," Tianqi said. "Current industrial solutions use always-on air pumps to actively generate suction, but these pumps are noisy and wasteful of energy. "
A paper on this suction cup was recently published in the journal Proceedings of the National Academy of Sciences (PNAS), and the video below demonstrates the suction cup. Interestingly, scientists at the University of Illinois have been working on an artificial octopus suction cup that uses a temperature-sensitive hydrogel.