An extreme close-up of a bird’s feathers with an amazing ability to hold water as it flies could inspire the next generation of absorbent materials.

Using high-resolution microscopes and 3D technology, researchers from Johns Hopkins University and the Massachusetts Institute of Technology have captured an unprecedented view of desert sandgrouse feathers, showcasing their unique feather architecture and revealing for the first time how they can hold so much water.

“It’s super fascinating to see how nature has managed to create such perfectly efficient structures for absorbing and retaining water,” said co-author Jochen Mueller, assistant professor in the Department of Civil and Systems Engineering at Johns. Hopkins, specializing in smart materials and design. “From a technical perspective, we believe the findings could lead to new bio-inspired creations.”

The book is published today (April 11) in Royal Society Interface Journal.

Sandgrouse found in African deserts typically nest about 20 miles from waterholes to stay safe from predators. To bring water home to the thirsty chicks, adult males perform one of nature’s finest examples of carrying, collecting water and flying home with it, a feat all the more extraordinary that the Sandgrouse retains around 15% of its body weight in water, and keeping most of it safe during a return flight of around 40 mph which takes around half an hour.

Male Sandgrouse are the only birds known to retain water like this – their specially adapted belly feathers are the key.

Other researchers first documented these extraordinary belly feathers more than 50 years ago. But it’s only here, thanks to modern technology, that the team can finally demonstrate how feathers work.

Mueller and MIT engineer Lorna J. Gibson focused on the microstructure of belly feathers using scanning electron microscopy, microcomputer tomography, optical microscopy, and 3D videography, in closely examining the stalks, each just a fraction of the width of a human hair, and the individual barbs even smaller.

The team greatly enlarged the feathers, observing them both dry and wet. Then, in a gesture as delicate as it is crucial, while magnifying the dry feathers, they were soaked in water, torn out, then plunged back in, like a sandgrouse at a watering hole.

“When you’re doing this type of work, you can’t even breathe, otherwise you blow it,” Mueller said.

Mueller described the structure of the individual feather as “magnificent”, with components optimized in many ways to trap and retain water, including how they bend, how the barbules form protective clusters in the shape of tent when wet and how the tubular structures inside each barb trap water.

Individual feathers held water through a forest of barbules near the shaft, working with the coiled barbules near the tip acting almost like plugs.

“That’s what got us excited, to see that level of detail,” Mueller said. “That’s what we need to understand in order to use these principles to create new materials.”

The team also computer-modeled the water consumption of the feathers.

Mueller and Gibson expect their findings to underpin future engineering designs requiring controlled absorption, secure retention and easy release of liquids.

Possible applications include the design of nets to collect and retain water from fog and dew in desert regions; and a water bottle designed to prevent awkward swinging and sloshing.

For the water bottle or sports backpack, he thinks of a design that holds plenty of liquid securely, but includes a feather-like interior system that prevents water from dripping out while someone is drinking. a move with. He thinks a hydration pack or bladder that could do that would be especially appreciated by runners.

He also imagines higher-level medical swabs that are easier to use, “where you can effectively absorb the liquid, but it’s much easier to release it,” he says, adding that the release feature was a problem for collection. of the COVID-19 nasal test. samples during the pandemic.

Next, the team plans to 3D print similar structures and pursue commercial applications.

The belly feathers used in this work were obtained from a single adult male Namaqua Sandgrouse (Pterocles namaqua) in the collection of the Harvard University Museum of Comparative Zoology.