Tag Archives: University of Sherbrooke

Fireflies and their jagged scales lead to brighter LEDs (light emitting diodes)

According to the Jan. 8, 2013 news item on ScienceDaily, scientists have used an observation about fireflies to make brighter LEDs (light emitting diodes),

The nighttime twinkling of fireflies has inspired scientists to modify a light-emitting diode (LED) so it is more than one and a half times as efficient as the original.

Researchers from Belgium, France, and Canada studied the internal structure of firefly lanterns, the organs on the bioluminescent insects’ abdomens that flash to attract mates. The scientists identified an unexpected pattern of jagged scales that enhanced the lanterns’ glow, and applied that knowledge to LED design to create an LED overlayer that mimicked the natural structure. The overlayer, which increased LED light extraction by up to 55 percent, could be easily tailored to existing diode designs to help humans light up the night while using less energy.

The Optical Society of America’s Jan. 8, 2013 news release, which originated the news item, describes how the scientists came to make their observations,

“The most important aspect of this work is that it shows how much we can learn by carefully observing nature,” says Annick Bay, a Ph.D. student at the University of Namur in Belgium who studies natural photonic structures, including beetle scales and butterfly wings.  When her advisor, Jean Pol Vigneron, visited Central America to conduct field work on the Panamanian tortoise beetle (Charidotella egregia), he also noticed clouds of twinkling fireflies and brought some specimens back to the lab to examine in more detail.

Fireflies create light through a chemical reaction that takes place in specialized cells called photocytes. The light is emitted through a part of the insect’s exoskeleton called the cuticle.  Light travels through the cuticle more slowly than it travels through air, and the mismatch means a proportion of the light is reflected back into the lantern, dimming the glow. The unique surface geometry of some fireflies’ cuticles, however, can help minimize internal reflections, meaning more light escapes to reach the eyes of potential firefly suitors.

In Optics Express papers, Bay, Vigneron, and colleagues first describe the intricate structures they saw when they examined firefly lanterns and then present how the same features could enhance LED design. Using scanning electron microscopes, the researchers identified structures such as nanoscale ribs and larger, misfit scales, on the fireflies’ cuticles. When the researchers used computer simulations to model how the structures affected light transmission they found that the sharp edges of the jagged, misfit scales let out the most light. The finding was confirmed experimentally when the researchers observed the edges glowing the brightest when the cuticle was illuminated from below.

“We refer to the edge structures as having a factory roof shape,” says Bay.  “The tips of the scales protrude and have a tilted slope, like a factory roof.” The protrusions repeat approximately every 10 micrometers, with a height of approximately 3 micrometers. “In the beginning we thought smaller nanoscale structures would be most important, but surprisingly in the end we found the structure that was the most effective in improving light extraction was this big-scale structure,” says Bay.

Here’s how the scientists applied their observations to LEDs (from the news release),

Human-made light-emitting devices like LEDs face the same internal reflection problems as fireflies’ lanterns and Bay and her colleagues thought a factory roof-shaped coating could make LEDs brighter. In the second Optics Express paper published today, which is included in the Energy Express  section of the journal, the researchers describe the method they used to create a jagged overlayer on top of a standard gallium nitride LED. Nicolas André, a postdoctoral researcher at the University of Sherbrooke in Canada, deposited a layer of light-sensitive material on top of the LEDs and then exposed sections with a laser to create the triangular factory-roof profile. Since the LEDs were made from a material that slowed light even more than the fireflies’ cuticle, the scientists adjusted the dimensions of the protrusions to a height and width of 5 micrometers to maximize the light extraction.

“What’s nice about our technique is that it’s an easy process and we don’t have to create new LEDs,” says Bay.  “With a few more steps we can coat and laser pattern an existing LED.”

Other research groups have studied the photonic structures in firefly lanterns as well, and have even mimicked some of the structures to enhance light extraction in LEDs, but their work focused on nanoscale features. The Belgium-led team is the first to identify micrometer-scale photonic features, which are larger than the wavelength of visible light, but which surprisingly improved light extraction better than the smaller nanoscale features. The factory roof coating that the researchers tested increased light extraction by more than 50 percent, a significantly higher percentage than other biomimicry approaches have achieved to date. The researchers speculate that, with achievable modifications to current manufacturing techniques, it should be possible to apply these novel design enhancements to current LED production within the next few years.

For those who care to investigate further,

Both articles (HTML version) are open access; PDF versions were not checked.

Could science funding in the European Union have an impact on Canadian nanotechnology?

Unexpectedly they’re upping the research budget in the European Union. According to the item online at  BBC News,

The EU has announced 6.4bn euros (£5.4bn) of funding for scientific research and innovation next year – a 12% increase on this year’s allocation.

The programme is aimed at creating more than 165,000 jobs and developing “a more competitive and greener Europe”, the European Commission says.

The focus is on tackling climate change, energy projects, food security, health and Europe’s ageing population.

Grants will be awarded to about 16,000 research bodies and businesses.

“Research and innovation are the only smart and lasting route out of crisis and towards sustainable and socially equitable growth,” said the EU Commissioner for Research and Innovation, Maire Geoghegan-Quinn.

“There is no other way of creating good and well-paid jobs that will withstand the pressures of globalisation.”

EU-funded research currently accounts for about 5% of the total public funding for research in the EU, she said.

The investment includes more than 600m euros for health research, about 206m euros of which will go into clinical trials for new drugs.

Nanotechnologies will get 270m euros, while about 600m euros is earmarked for advanced computer technologies. [emphasis mine]

Another 400m euros is to be spent on computer applications that address the challenges of building a low-carbon economy and managing ageing populations.

I was inclined to view it as a piece of delightful news without really analyzing it, then David Bruggeman (Pasco Phronesis) made a salient comment,

I suspect that the European spending will be insufficient even if individual nations hold the line on their own science funding. Because even those nations are looking at significant cuts to their universities, which affect both the training of the next generation of researchers and a certain amount of research. At best the funding boosts and cuts will be a wash, but the future doesn’t look like the best. What might happen is a greater shift in attention to European Union level research compared to country level research.

David also provides a brief description of the  ‘framework programme’ that the European Union uses to fund science research so that readers (such as me) have a better understanding of the bigger picture. If you’re interested in this kind of thing, do check out his posting.

David’s commentary was particularly timely as, this morning, I came across an article about the French government funding nanotechnology research in Canada (Sherbrooke, Québec to be precise). Since the article is in French, I’m going to be relying on my translation skills (Note: I will reproduce at least some of the French, so do let me know if you spot any errors.)

There is an abbreviated version of the article (Nanotechnologies: un petit bout de France à L’UdeS) by Jonathan Custeau for the Sherbrooke Tribune here (fyi, somebody sent me a copy of the full article).

The University of Sherbrooke’s current nanotechnology laboratory (Laboratoire international associé en nanotechnologies et nanosystèmes [LIA-LN2]) is about to receiving funding to the tune of ! million Euros over three years from France’s CNRS (Centre National de la Recherche Scientifique) putting  it in a category occupied by only eight other labs in the world.

I gather the lab’s current LIA-LN2 status is a consequence of previous French funding since the university’s vice-president of research describes the current bonanza as ‘jumping to a new level’, i.e. jumping to Unité mixte international (UMI) status,

“Nous étions tellement en avance que nous sautons à un autre niveau”, fait valoir Jacques Beauvais, vice-recteur à la recherche de l’Université de Sherbrooke.

L’autre niveau, c’est l’Unité mixte internationale, un laboratoire financé par le Centre national de la recherche scientifique (CNRS français. Il n’en existe que huit à travers le monde.

“Une UMI coûte très cher, parce que c’est un vrai laboratoire, avec des chercheurs financés par le CNRS, des fonds de recherches français et européens. C’est comme s’il y avait un bout de France sur le campus de l’Université de Sherbrooke”, fait valoir Vincent Aimez, codirecteur du LIA-LN2.

The nanotechnology researchers at the University of Sherbrooke (L’UdeS) have been liaising and collaborating with researchers in Varennes, Lyon, and Grenoble, France for over two years,  so this new funding is an acknowledgment of the quality of their work.

Bravo—the award is all the more extraordinary given the concerns about science and university funding in Europe.

January 2012 is the launch date for the University of Sherbrooke’s UMI which will have a focus on bringing at least some of the academic research to the market. Miniaturized integrated circuit boards are mentioned specifically and my translation skills failed a bit here,

Les applications des recherches pourraient notamment permettre de relever le défi de la miniaturisation des puces électroniques [integrated circuit boards?]. “Nous cherchons à faire des puces avec plus de fonctions, mais qui consomment moins d’énergie, pour qu’elles restent efficaces pendant un mois par exemple. Nous voulons aussi développer des biocapteurs [?] pour des contrôles environnementaux [?] ou des analyses médicales [medical diagnostics?]”, précise Abdelkader Souifi, également codirecteur du LIA-LN2.

I found the comments regarding products quite interesting in light of the Québec government’s recent moves to improve innovation in that province as per the article (June 30, 2010) by Peter Hadekel in the Montréal Gazette. (Idle thought: This casts a new light on the recent Domtar-FPInnovations collaboration on nanocrystalline cellulose (my July 16, 2010 posting).