Jellyfish inspire flexible pumps
We’ve seen the swimming motions of fish emulated by underwater robots several times before, but jellyfish (with an exception or two) don’t seem to inspire mechanical imitation quite as much. A student at the California Institute of Technology in Pasadena (Caltech), however, thinks that their unique propulsion system might be the perfect model for another type of technology: tiny pumps that can be implanted in peoples’ bodies, or used in soft robotics.
The pumps are the brainchild of grad student Janna Nawroth, who is working on the research project with Caltech jellyfish propulsion expert John Dabiri. “Most pumps are made of rigid materials,” said Nawroth. “For medical pumps inside the human body, we need flexible pumps because they move fluids in a much gentler way that does not destroy tissues and cells.”
The flows and eddies created by swimming jellyfish can be quantified by what is known as a Reynolds number. It turns out that the Reynolds numbers for moon jellyfish of a wide range of ages and sizes are in the right range for medical applications.
Nawroth has also observed how tiny juvenile moon jellies take advantage of a layer of water that adheres to their outer surface, using it to close the gaps between their lappets (“arms”), so that their bodies are able to act more like a paddle and less like a sieve. Additionally, it has been noted that they have a network of neuronal “pacemakers” throughout their bodies, that allow them to control their contractions, according to the conditions. If such a system could be reproduced using human technology, it could allow for flexible pumps with consistent yet tunable performance.
Photos courtesy J. Nawroth