Clingfish Offer Inspiration For New Medical Devices
The northern clingfish happens to be about the size and shape of a fish stick, but it is also a very sticky fish in a different sense.
If these fish were scaled up to human size, the suction cup-like discs on their undersides would easily be strong enough to lift several cars, leading researchers at the University of Washington's Friday Harbor Laboratories to study how their sticking power could be used for technologies as diverse as medical devices and whale tags.
Developing devices that stick to wet, uneven surfaces is a major challenge even for top scientists and engineers, but the northern clingfish (Gobiesox maeandricus) does so with ease. Prying one off the slimy surface of a rock in its native waters in the Puget Sound in Washington state would require pulling with a force 150 times greater than the fish's body weight. The fish range along the West Coast as far south as Baja, Calif.
The key to the northern clingfish's super suction strategy is a disc located on its underside. Tiny hairlike structures found along the edges of the disc increase the friction between the edge of the disc and the surface that it is stuck to. There are layers of the hairlike structures, making it well able to cling to surfaces of varying levels of roughness.
"In most cases suction disks fail because the edges slide inwards," says principal investigator Adam Summers. "That is much harder with these fishes because the edges have little hairs that make it harder to slide across a rough surface."
Similarities between the slimy, uneven surfaces that the northern clingfish lives amongst underwater and the wet, irregular surfaces found within human bodies inspired the researchers to explore how medical devices could take advantage of the fish's technique. Summers highlights laproscopic surgery, which involves working through very small incisions using a lighted tube, as a likely target for future applications. Holding internal organs and other tissues in place while working in such tight quarters can help procedures go more smoothly, but doing so has proven problematic.
"Current technology grabs with clamps and many tissues simply can't be grabbed," Summers says.
More research is needed before a clingfish-inspired surgical tool becomes a reality, but this is just one of the potential applications for this technology that researchers are already looking into. Currently, researchers conducting long-term studies of whales often tag the animals by puncturing their skin with a dart, which is ethically questionable and difficult to obtain a permit for, but attaching the tags using clingfish-like adhesive could provide a noninvasive solution. While research on how humans can take advantage of the clingfish's extraordinary suction abilities is still in the preliminary stages, these possibilities remind us that nature is full of inspiration for innovation.