Nanotechnology Now

Our NanoNews Digest Sponsors

Heifer International

Wikipedia Affiliate Button

Home > Press > Silk fibers could be high-tech ‘natural metamaterials’

New research suggests fibers from a silkworm’s cocoon may represent “natural metamaterials,” a discovery with various technological and scientific implications. (Purdue University image/Young Kim)
New research suggests fibers from a silkworm’s cocoon may represent “natural metamaterials,” a discovery with various technological and scientific implications. (Purdue University image/Young Kim)

Abstract:
Anderson light localization in biological nanostructures of native silk Seung Ho Choi1†, Seong-Wan Kim2†, Zahyun Ku3†, Michelle A. Visbal-Onufrak1, Seong-Ryul Kim2, Kwang-Ho Choi2, Hakseok Ko4,5, Wonshik Choi4,5, Augustine M. Urbas3, Tae-Won Goo6, and Young L. Kim1,7,8 1Weldon School of Biomedical Engineering, Purdue University, Indiana 47907, USA, 2Department of Agricultural Biology, National Institute of Agricultural Sciences, Rural Development Administration, Wanju 55365, Republic of Korea, 3Materials and Manufacturing Directorate, Air Force Research Laboratory, Wright-Patterson Air Force Base, Ohio 45433, USA, 4Center for Molecular Spectroscopy and Dynamics, Institute for Basic Science, Seoul 02841, Republic of Korea, 5Department of Physics, Korea University, Seoul 02841, Republic of Korea, 6Department of Biochemistry, School of Medicine, Dongguk University, Gyeongju 38066, Republic of Korea, 7Regenstrief Center for Healthcare Engineering, Purdue University, Indiana 47907, USA, 8Purdue Quantum Center, Purdue University, Indiana 47907, USA †These authors contributed equally to this work Correspondence: Young Kim, youngkim@purdue.edu Light in biological media is known as freely diffusing because interference is negligible. Here, we show Anderson light localization in quasi-two-dimensional protein nanostructures produced by silkworms (Bombyx mori). For transmission channels in native silk, the light flux is governed by a few localized modes. Relative spatial fluctuations in transmission quantities are proximal to the Anderson regime. The sizes of passive cavities (smaller than a single fibre) and the statistics of modes (decomposed from excitation at the gain-loss equilibrium) differentiate silk from other diffusive structures sharing microscopic morphological similarity. Because the strong reflectivity from Anderson localization is combined with the high emissivity of the biomolecules in infrared radiation, silk radiates heat more than it absorbs for passive cooling. This collective evidence explains how a silkworm designs a nanoarchitectured optical window of resonant tunnelling in the physically closed structures, while suppressing most of transmission in the visible spectrum and emitting thermal radiation.

Silk fibers could be high-tech ‘natural metamaterials’

West Lafayette, IN | Posted on January 31st, 2018

New research has demonstrated how the nano-architecture of a silkworm’s fiber causes “Anderson localization of light,” a discovery that could lead to various innovations and a better understanding of light transport and heat transfer.

The discovery also could help create synthetic materials and structures that realize the phenomenon, named after Nobel laureate Philip Anderson, whose theory describes how electrons can be brought to a complete halt in materials due to their “scattering and defects.” The new findings relate not to electrons, but to light transport.

Researchers demonstrated how the nano-architecture of the silk fibers is capable of light “confinement,” a trait that could provide a range of technological applications including innovations that harness light for new types of medical therapies and biosensing. This light-confinement effect in biological and natural tissue, which was unexpected, is made possible by the Anderson localization of light, said Young Kim, an associate professor in Purdue University’s Weldon School of Biomedical Engineering.

The new findings suggest silk fibers may represent “natural metamaterials” and “natural metastructures,” Kim said. (A YouTube video is available at https://youtu.be/RtgNdibMAhw )

Various research groups have created synthetic “metamaterials” capable of the ultra-efficient control of light. However, metamaterials have limitations because they are often difficult to scale up for commercial production and pose other challenges. Because silk’s nano-architecture is “disordered” instead of meticulously designed periodic structures, the findings suggest a strategy to produce metamaterials that are less expensive to fabricate and manufacture and easier to scale up for industry.

“This is fascinating because realizing Anderson localization of light is extremely challenging, yet we now know that it can be achieved using irregular, disordered nanostructures to create highly packed nanomaterials for strong light scattering as a silkworm produces a silk fiber and spins a cocoon shell in nature,” Kim said.

The findings are detailed in a paper appearing on Wednesday (Jan. 31) in the journal Nature Communications. The paper’s lead author is Purdue postdoctoral research associate Seung Ho Choi.

“Our findings could open up new possibilities for metamaterials and metastructures,” said Kim, who is leading research to better understand the underlying reasons for silk’s white, silvery and lustrous reflection. “I know this is an oxymoron, but we are saying silk fibers represent ‘natural metamaterials’ and ‘natural metastructures.’”

The silk fibers are 10-20 microns in diameter and contain thousands of tiny nanofibrils, each around 100 nanometers wide. For perspective, a human hair is roughly 100 microns in diameter.

A silk fiber has numerous “scattering centers” inside. Anderson localization arises from this light scattering due to disorder in the nanostructure.

“Silk has many nanofibrils, which individually scatter light,” Kim said.

For the Anderson localization to occur, there must be both scattering and interference between scattered light waves. Densely packed irregular nanostructures cause light waves to interfere with each other, sometimes in destructive and sometimes in constructive ways. If constructive, the light is intensified.

“If waves are constructively interfering, this forms a very high energy inside the disordered media,” Choi said.

The small size and roughly parallel arrangement of the nanofibrils are conducive to the effect. The scattering power is maximized when there are many scattering centers and when their size is comparable to the wavelength of the light, both criteria found in the silk fibers.

Whereas commercial optical fibers must be specially engineered with a reflective coating, or cladding, to allow for the confinement of light, the silk fibers are able to achieve the feat naturally due to Anderson localization of light. The Anderson localization creates “modes” that make confinement of light possible without carefully engineered periodic structures. Instead, the same confinement is possible with disordered, more random designs.

“We found that most transmission of light disappears in most of the silk surface. However, counterintuitively, in a small area we found that the energy is confined, and this confined energy is transmitted through localized modes,” Kim said. “The localized mode is a unique pathway for energy flow.”

Although biological structures such as silk diffuse light, other natural materials with similar microstructures do not possess the localized, modes making Anderson localization of light possible.

“Such a difference makes silk particularly interesting for radiative heat transfer.” Kim said. The silk has a high emissivity for infrared light, meaning it readily radiates heat, or infrared radiation, while at the same time being a good reflector of solar light. Because the strong reflectivity from Anderson localization is combined with the high emissivity of the biomolecules in infrared radiation, silk radiates more heat than it absorbs, making it ideal for passive, or “self-cooling.”

“You may have heard that silk underwear can keep you cooler in summertime and warmer in winter,” Kim said. “We have learned the basic mechanism behind this observation.”

The work is led by researchers in Purdue’s Weldon School of Biomedical Engineering; the Department of Agricultural Biology of the National Institute of Agricultural Sciences in South Korea; and the Materials and Manufacturing Directorate of the U.S. Air Force Research Laboratory. A complete list of co-authors is available in the abstract.

“Our findings could open up largely unexplored opportunities for engineering, energy, and biomedical areas,” Kim said. “However, while direct applications could be possible, we really want to learn from silk to help develop material synthesis and design processes in the future.”

The work was funded by the Cooperative Research Program for Agriculture Science & Technology Development in South Korea and the U.S. Air Force Office of Scientific Research.

####

For more information, please click here

Contacts:
Writer:
Emil Venere
765-494-4709


Sources:
Young L. Kim
765-496-2445


Seung Ho Cho


The materials were produced by
Erin Easterling
Purdue College of Engineering digital producer
765-496-3388

Copyright © Purdue University

If you have a comment, please Contact us.

Issuers of news releases, not 7th Wave, Inc. or Nanotechnology Now, are solely responsible for the accuracy of the content.

Bookmark:
Delicious Digg Newsvine Google Yahoo Reddit Magnoliacom Furl Facebook

Related Links

The research paper is available at:

Other video is accessible on Google Drive at:

Related News Press

News and information

Getting electrons to move in a semiconductor: Gallium oxide shows high electron mobility, making it promising for better and cheaper devices April 24th, 2018

JPK reports on research of the Mestroni Lab at the University of Colorado Denver which use the JPK NanoWizard® AFM to help in the characterization of cardiomyopathies April 24th, 2018

Organic solar cells reach record efficiency, benchmark for commercialization April 23rd, 2018

Remote-control shoots laser at nano-gold to turn on cancer-killing immune cells April 20th, 2018

Govt.-Legislation/Regulation/Funding/Policy

Organic solar cells reach record efficiency, benchmark for commercialization April 23rd, 2018

Remote-control shoots laser at nano-gold to turn on cancer-killing immune cells April 20th, 2018

Salt boosts creation of 2-D materials: Rice University scientists show how salt lowers reaction temperatures to make novel materials April 18th, 2018

Quantum shift shows itself in coupled light and matter: Rice University scientists corral, quantify subtle movement in condensed matter system April 16th, 2018

Possible Futures

Getting electrons to move in a semiconductor: Gallium oxide shows high electron mobility, making it promising for better and cheaper devices April 24th, 2018

JPK reports on research of the Mestroni Lab at the University of Colorado Denver which use the JPK NanoWizard® AFM to help in the characterization of cardiomyopathies April 24th, 2018

Organic solar cells reach record efficiency, benchmark for commercialization April 23rd, 2018

Remote-control shoots laser at nano-gold to turn on cancer-killing immune cells April 20th, 2018

Nanomedicine

JPK reports on research of the Mestroni Lab at the University of Colorado Denver which use the JPK NanoWizard® AFM to help in the characterization of cardiomyopathies April 24th, 2018

Remote-control shoots laser at nano-gold to turn on cancer-killing immune cells April 20th, 2018

Observing biological nanotransporters: Chemistry April 19th, 2018

Nanobiotix Shows NBTXR3 Nanoparticles Can Stoke Anti-Tumor Immune Response April 17th, 2018

Discoveries

Getting electrons to move in a semiconductor: Gallium oxide shows high electron mobility, making it promising for better and cheaper devices April 24th, 2018

JPK reports on research of the Mestroni Lab at the University of Colorado Denver which use the JPK NanoWizard® AFM to help in the characterization of cardiomyopathies April 24th, 2018

Organic solar cells reach record efficiency, benchmark for commercialization April 23rd, 2018

Remote-control shoots laser at nano-gold to turn on cancer-killing immune cells April 20th, 2018

Materials/Metamaterials

Getting electrons to move in a semiconductor: Gallium oxide shows high electron mobility, making it promising for better and cheaper devices April 24th, 2018

Organic solar cells reach record efficiency, benchmark for commercialization April 23rd, 2018

Salt boosts creation of 2-D materials: Rice University scientists show how salt lowers reaction temperatures to make novel materials April 18th, 2018

Individual impurity atoms detectable in graphene April 18th, 2018

Announcements

Getting electrons to move in a semiconductor: Gallium oxide shows high electron mobility, making it promising for better and cheaper devices April 24th, 2018

JPK reports on research of the Mestroni Lab at the University of Colorado Denver which use the JPK NanoWizard® AFM to help in the characterization of cardiomyopathies April 24th, 2018

Organic solar cells reach record efficiency, benchmark for commercialization April 23rd, 2018

Remote-control shoots laser at nano-gold to turn on cancer-killing immune cells April 20th, 2018

Interviews/Book Reviews/Essays/Reports/Podcasts/Journals/White papers

Getting electrons to move in a semiconductor: Gallium oxide shows high electron mobility, making it promising for better and cheaper devices April 24th, 2018

JPK reports on research of the Mestroni Lab at the University of Colorado Denver which use the JPK NanoWizard® AFM to help in the characterization of cardiomyopathies April 24th, 2018

Organic solar cells reach record efficiency, benchmark for commercialization April 23rd, 2018

Remote-control shoots laser at nano-gold to turn on cancer-killing immune cells April 20th, 2018

Military

Organic solar cells reach record efficiency, benchmark for commercialization April 23rd, 2018

Quantum shift shows itself in coupled light and matter: Rice University scientists corral, quantify subtle movement in condensed matter system April 16th, 2018

New 4-D printer could reshape the world we live in March 20th, 2018

Imaging technique pulls plasmon data together: Rice University scientists' hyperspectral method analyzes many plasmonic nanoparticles in an instant March 16th, 2018

Food/Agriculture/Supplements

HTA to Present European Strategy for Competitive Micro- and Nanotechnologies & Smart Systems: Special Event in Brussels on April 24 Gathers Research Institutes’ CEOs, European Commissioners and Key European Industrials April 17th, 2018

Twisting laser light offers the chance to probe the nano-scale: A new method to sensitively measure the structure of molecules has been demonstrated by twisting laser light and aiming it at miniscule gold gratings to separate out wavelengths: April 5th, 2018

Graphene on toast, anyone? Rice University scientists create patterned graphene onto food, paper, cloth, cardboard February 13th, 2018

Nanowrinkles could save billions in shipping and aquaculture Surfaces inspired by carnivorous plants delay degradation by marine fouling January 17th, 2018

Energy

Organic solar cells reach record efficiency, benchmark for commercialization April 23rd, 2018

Psst! A whispering gallery for light boosts solar cells April 14th, 2018

High efficiency solar power conversion allowed by a novel composite material: A composite thin film developed at INRS improves significantly solar cells' power conversion efficiency April 10th, 2018

Light 'relaxes' crystal to boost solar cell efficiency: Rice, Los Alamos discovery advances case for perovskite-based solar cells April 6th, 2018

Grants/Sponsored Research/Awards/Scholarships/Gifts/Contests/Honors/Records

Getting electrons to move in a semiconductor: Gallium oxide shows high electron mobility, making it promising for better and cheaper devices April 24th, 2018

Remote-control shoots laser at nano-gold to turn on cancer-killing immune cells April 20th, 2018

Lifeboat Foundation funds flying 3D-printed classroom cubesats with Perlan II April 16th, 2018

Thermo Scientific Krios G3i Cryo-Electron Microscope Wins Gold Edison Award: Krios G3i helps scientists better understand disease mechanisms in order to accelerate cures April 12th, 2018

NanoNews-Digest
The latest news from around the world, FREE



  Premium Products
NanoNews-Custom
Only the news you want to read!
 Learn More
NanoStrategies
Full-service, expert consulting
 Learn More











ASP
Nanotechnology Now Featured Books




NNN

The Hunger Project