Dragonfly larvae may hold the key to a range of engineering and medical applications, according to new research.
Scientists at the California Institute of Technology (Caltech) examined the jet propulsion system of Anisopteran dragonfly larvae as a method for advanced prosthetic heart valves.
One of nature’s more beautiful insects, the dragonfly (Anisoptera) is a voracious predator, in their aquatic larval stage (known as nymphs or naiads) and as adults.
The flying wonders spend most of their life subaquatic, breathing through gills in their rectum and propelling themselves by expelling water through the anus.
It’s their active tri-leaflet valves, however, that are most intriguing to Caltech professor Morteza Gharib. Larvae have independent control over each “leaflet,” allowing them to change the size and asymmetry of the water jet.
“The way the dragonfly larvae use their unique adaptation to control the jet direction has previously been overlooked,” according to Gharib, senior study.
Unlike squid or salps, which simply point their funnels or siphons in a desired direction, dragonfly larvae adjust their course based on respiration and propulsion.
“Coupled with the changing valve size, the larvae’s diagonal respiratory jet appears to aid the inhalation process and prevent re-inhaling the exhaled fluid,” Gharib said in a statement. “The straight propulsive jetting, meanwhile, appears to help with the production and utilization of the thrust.”
Which is to say, researchers may have found new ways to address old problems in the engineering and biomedical spheres—particularly those fields that use jet control.
“For example, synthetic jets are gaining popularity in areas like flow control, propulsion, and heat transfer,” lead author Chris Roh, a postdoctoral scholar in aerospace at Caltech, said. “The dragonfly’s dynamic asymmetry control at the orifice could inspire a new way to adjust the jet directionality in synthetic jet systems. If the asymmetric orifice control is integrated into synthetic jets, the systems may be able to achieve a more diverse flow profile.”
The larvae’s leaflet valves also have significant applications in medical devices that require flow control, like prosthetic heart valves.
“The current tri-leaflet prosthetic heart valves suffer from prosthesis-patient mismatch, which is caused by the unnatural blood flow that over time can cause blood clots or infection in the walls of the aortic trunk,” Gharib explained. “In this regard, a valve asymmetry could prove useful as an adjustable parameter, which can direct the prosthetic’s blood flow to match individual patients’ natural blood flow.”
Read more about dragonfly larvae in Gharib and Roh’s study, published this week in the journal Bioinspiration and Biomimetics.
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