• Graham Harris

The world's most efficient light.

Fireflies are an amazing insect. There are thousands of species of them - none of which are actually flies (they are beetles) and none of which are actually on fire (although most of which can create their own light, and they principally do so to attract a mate).

Creating your own light - bioluminescence - is amazing enough, but fireflies do this with an efficiency which is astounding. In fact, the light of a firefly is 100% efficient! Yep, 100% of the chemical energy involved in creating their bioluminescence is converted into light - without any production of heat!

By comparison, human methods of lighting up the night have traditionally been nowhere near this gold standard of efficiency. Traditional incandescent lightbulbs are only around 10% efficient - with 90% of the electrical energy consumed turning into heat rather than light (which is why touching an incandescent bulb would burn your fingers). Although there has been a rapid transition to a more efficient light - LEDs - these are still far off from being 100% efficient.

However, researchers at Penn State University have recently turned to the firefly for inspiration in making further improvements to LED design. According to the researchers:

"Fireflies and LEDs face similar challenges in releasing the light that they produce because the light can reflect backwards and is lost".

The team at Penn State go on to say that this problem is related to what is called "extraction efficiency" (the efficiency with which the light created actually gets out of the LED). It turns out that fireflies have an asymmetrical textured surface that a) creates greater surface area and b) increases randomization of light reflections, which give the light more chance of escaping the surface. The smart folks at the University then uses 3D nanoprinting to create an LED with a firefly-inspired asymmetrical textured surface that they calculate has yielded a light extraction efficiency of 90%.

From a climate change perspective, inefficiency means energy consumed, and therefore money paid and greenhouse gases emitted, that didn't need to be. How cool to think that the firefly - owner of the world's most efficient light - is inspiring technological innovations that could help us tackle our carbon footprint.

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