Tag Archives: feathers

Stellar’s jay gives structural colo(u)r a new look

Leave a reply

The structural colo(u)r stories I’ve posted previously identify nanostructures as the reason for why certain animals and plants display a particular set of optical properties, colours that can’t be obtained by pigment or dye. However, the Stellar’s jay structural colour story is a little different.

Caption: Bio-inspired bright structurally colored colloidal amorphous array enhanced by controlling thickness and black background. ©Yukikazu Takeoka

From a May 8, 2017 news item on ScienceDaily,

A Nagoya University-led [Japan] research team mimics the rich color of bird plumage and demonstrates new ways to control how light interacts with materials.

Bright colors in the natural world often result from tiny structures in feathers or wings that change the way light behaves when it’s reflected. So-called “structural color” is responsible for the vivid hues of birds and butterflies. Artificially harnessing this effect could allow us to engineer new materials for applications such as solar cells and chameleon-like adaptive camouflage.

Inspired by the deep blue coloration of a native North American bird, Stellar’s jay, a team at Nagoya University reproduced the color in their lab, giving rise to a new type of artificial pigment. This development was reported in Advanced Materials.

“The Stellar’s jay’s feathers provide an excellent example of angle-independent structural color,” says last author Yukikazu Takeoka, “This color is enhanced by dark materials, which in this case can be attributed to black melanin particles in the feathers.

A May 8, 2017 Nagoya University press release (also on EurekAlert), which originated the news item, expands on the theme of what makes the structural colour of a Stellar’s jay feather different,

In most cases, structural colors appear to change when viewed from different perspectives. For example, imagine the way that the colors on the underside of a CD appear to shift when the disc is viewed from a different angle. The difference in Stellar’s jay’s blue is that the structures, which interfere with light, sit on top of black particles that can absorb a part of this light. This means that at all angles, however you look at it, the color of the Stellar’s Jay does not change.

The team used a “layer-by-layer” approach to build up films of fine particles that recreated the microscopic sponge-like texture and black backing particles of the bird’s feathers.

To mimic the feathers, the researchers covered microscopic black core particles with layers of even smaller transparent particles, to make raspberry-like particles. The size of the core and the thickness of the layers controlled the color and saturation of the resulting pigments. Importantly, the color of these particles did not change with viewing angle.

“Our work represents a much more efficient way to design artificially produced angle-independent structural colors,” Takeoka adds. “We still have much to learn from biological systems, but if we can understand and successfully apply these phenomena, a whole range of new metamaterials will be accessible for all kinds of advanced applications where interactions with light are important.”

Here’s a link to and a citation for the paper,

Bio-Inspired Bright Structurally Colored Colloidal Amorphous Array Enhanced by Controlling Thickness and Black Background by Masanori Iwata, Midori Teshima, Takahiro Seki, Shinya Yoshioka, and Yukikazu Takeoka. Advanced Materials DOI: 10.1002/adma.201605050 Version of Record online: 26 APR 2017

© 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

This paper is behind a paywall.

Ordinarily, I’d expect to see the term ‘nano’ somewhere in the press release or in the abstract but that’s not the case here. The best I could find was a reference to ‘submicrometer-sized .. particles” in the abstract. I suppose that could refer to the nanoscale but given that a Japanese researcher (Norio Taniguchi in 1974) coined the phrase ‘nanotechnology’ to describe research at that scale it seems unlikely that Japanese researchers some forty years later wouldn’t use that term when appropriate.

Feathered flight and nanoscale research

Leave a reply

Today (Oct. 24, 2014) is a day for flight as I posted this earlier, NASA, super-black nanotechnology, and an International Space Station livestreamed event. With that in mind, here’s an Oct. 23, 2014 news item on Nanowerk about feathers,

Scientists from the University of Southampton [UK] have revealed that feather shafts are made of a multi-layered fibrous composite material, much like carbon fibre, which allows the feather to bend and twist to cope with the stresses of flight.

Since their appearance over 150 million years ago, feather shafts (rachises) have evolved to be some of the lightest, strongest and most fatigue resistant natural structures. However, relatively little work has been done on their morphology, especially from a mechanical perspective and never at the nanoscale.

An Oct. 22, 2014 University of Southampton news release, which originated the news item, describes the study, which may have paleontological implications, in more detail,

The study, which is published by the Royal Society in the journal Interface, is the first to use nano-indentation, a materials testing technique, on feathers. It reveals the number, proportion and relative orientation of rachis layers is not fixed, as previously thought, and varies according to flight style.

Christian Laurent, from Ocean and Earth Science at the University of Southampton, lead author of the study, says: “We started looking at the shape of the rachis and how it changes along the length of it to accommodate different stresses. Then we realised that we had no idea how elastic it was, so we indented some sample feathers.

“Previously, the only mechanical work on feathers was done in the 1970s but under the assumption that the material properties of feathers are the same when tested in different directions, known as isotropic – our work has now invalidated this.”

The researchers tested the material properties of feathers from three birds of different species with markedly different flight styles; the Mute Swan (Cygnus olor), the Bald Eagle (Haliaeetus leucocephalus) and the partridge (Perdix perdix).

Christian, who led the study as part of his research degree (MRes) in Vertebrate Palaeontology, adds: “Our results indicate that the number, and the relative thickness, of layers around the circumference of the rachis and along the feather’s length are not fixed, and may vary either in order to cope with the stresses of flight particular to the bird or to the lineage that the individual belongs to.”

The researchers soon hope to fully model feather functions and link morphological aspects to particular flight styles and lineages, which has several palaeontogical implications and engineering applications.

Christian says: “We hope to be able to scan fossil feathers and finally answer a number of questions – What flew first? Did flight start from the trees down, or from the ground up? Could Archaeopteryx fly? Was Archaeopteryx the first flying bird?

“In terms of engineering, we hope to apply our future findings in materials science to yacht masts and propeller blades, and to apply the aeronautical findings to build better micro air vehicles in a collaboration [with] engineers at the University.”

Here’s a link to and a citation for the paper,

Nanomechanical properties of bird feather rachises: exploring naturally occurring fibre reinforced laminar composites by Christian M. Laurent, Colin Palmer, Richard P. Boardman, Gareth Dyke, and Richard B. Cook. J. R. Soc. [Journal of the Royal Society] Interface 6 December 2014 vol. 11 no. 101 20140961 doi: 10.1098/​rsif.2014.0961  Published 22 October 2014

This is an open access paper.