- Category: Energy Efficiency
10 Jan 2013
- Published on Thursday, 10 January 2013 09:24
- Hits (1768)
The soft twinkling of fireflies in the night sky may awaken thoughts of romance in poets and lovers, but for an international group of scientists, it could spur the creation of a better light-emitting diode.
Fireflies’ lanterns, the bioluminescent organs on their abdomens, light up to help the insects attract both mates and prey. By studying the internal structure of these organs, a team of researchers from Belgium, France and Canada were able to increase the light extraction of an L.E.D.
By mimicking a pattern of jagged scales found on the exoskeleton of fireflies, the created an L.E.D. overlayer that could raise light extraction by up to 55 percent. The overlayer can be easily tailored with existing diode designs for more energy efficient lighting.
In a firefly, light is produced through a chemical reaction that happens in special cells called photocycles. This light is then emitted through a part of the insect’s exoskeleton called the cuticle.
Usually, light travels slower through the cuticle than it does through air. The mismatch means some of the light is reflected back, however, some fireflies’ cuticles posses a unique jagged surface geometry which minimizes these internal reflections, allowing more light to escape for a brighter glow.
The researchers took a closer look at the cuticles of fireflies from the genus Photuris, found in Latin America and the United States.
They found that some of the cuticles are covered with large, jagged edge scales that they liken to the shape of a factory roof – protruding and tilted. These protrusions raise off the scale at a height of approximately 3 micrometers every 10 micrometers.
The researchers duplicated this pattern in their L.E.D. overlayer by depositing a layer of light-sensitive-material on top of the L.E.D.s then exposing sections a laser. The laser etched out protrusions to a height and width of 5 micrometers for maximum light extraction.
The findings were published in the Otical Scoeity’s open-access journal Optic Express. The researchers included scientists from the University of Namura and the University of Sherbrooke. They will continue to look at other species of fireflies for ways to further improve their current overlayer design. – EcoSeed Staff