Four years ago, we heard how scientists had gained a new understanding of the Northern clingfish's ability to … well, to cling to things. Utilizing that knowledge, they've now developed a suction cup that adheres to rough surfaces, outperforming the actual fish itself.
The clingfish has a disc-shaped combination of two fins on its underside, which it uses to very strongly adhere to underwater surfaces such as rocks.
Led by Dr. Petra Ditsche and Prof. Adam Summers, researchers at the University of Washington discovered that the secret lies in the rim of that disc, which is covered in layers of tiny hair-like structures of varying sizes. This arrangement creates friction along the rim, allowing it to adhere to rough, wet or slimy surfaces. Additionally, the flexibility and elasticity of the disc let it conform to uneven surfaces, helping it to maintain contact.
As a result, the Northern clingfish can support up to 230 times its own body weight when lifted, yet also release its hold and swim away whenever it wants. Such tenacity would be desirable in applications such as whale-tracking tags, ship-hull-cleaning robots, surgical devices, or even just shower caddies.
To that end, Ditsche and Summers set about trying to replicate the clingfish disc, utilizing microstructured manmade materials. They've now succeeded, utilizing a combination of materials to create a suction cup that's rigid enough to maintain tension, while also being soft and flexible enough to conform to rough surfaces.
In lab tests that involved sticking the cup to various surfaces and then using a machine to pull on it until it failed, the best versions of the device consistently performed better than actual clingfish discs. The scientists now hope to commercialize the technology, after establishing how it's affected by factors such as temperature and sun exposure.
"I like to say, nature is always best," says Ditsche. "In this case, when considering their attachment force, our suction cups are better."
The research is described in a paper that was recently published in the journal Philosophical Transactions of the Royal Society B.
Source: University of Washington