Science

Scientists find natural photovoltaic cell in hornet, and copy it

Scientists find natural photov...
An Oriental hornet, whose yellow and brown exoskeleton is able to turn sunlight into electricity (Photo: Matti Paavola)
An Oriental hornet, whose yellow and brown exoskeleton is able to turn sunlight into electricity (Photo: Matti Paavola)
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An Oriental hornet, whose yellow and brown exoskeleton is able to turn sunlight into electricity (Photo: Matti Paavola)
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An Oriental hornet, whose yellow and brown exoskeleton is able to turn sunlight into electricity (Photo: Matti Paavola)

It’s no big mystery why turtles and other reptiles bask in the sun – being cold-blooded animals, they’re gathering heat to warm their bodies, so they can be active. Recently, however, scientists from Israel and the UK discovered that the Oriental hornet has been putting a “high-tech” spin on that model... the outer layers of its body work as a natural photovoltaic cell, converting sunlight to electricity. The scientists then proceeded to create a cell of their own, using the hornet as their inspiration.

The study was led by Dr. Marian Plotkin of Tel-Aviv University. It had been observed that the hornets’ underground nest-digging activity increased with the intensity of the sunlight, whereas most wasps tend to be more active in the early morning. This caused the late Prof. Jacob S. Ishay to suspect that the insects were utilizing solar radiation.

Plotkin’s team discovered that the secret lies in the hornets’ outer body shell, or exoskeleton. They found that the cuticle material making up the brown portions of the shell consists of an array of grooves, each one 160 nanometers high. The yellow parts of the body, however, are made up of cuticle material bearing a series of interlocking 50nm-tall oval-shaped protrusions, each one housing a pinhole-sized depression.

The antireflective brown material splits any sunlight that hits it into several diverging beams. These beams proceed into the cuticle, where they encounter a several-layer-thick sheet-like structure. Within each layer are rod-like structures embedded in a protein matrix, the rods made from chains of the polymer chitin. It is this complex structure that keeps the solar light beams trapped within the cuticle, bouncing between layers – the team noted that some man-made solar cells use a similar technique, in which light is bounced back and forth between layers of nanorods.

So, why the yellow? The yellow cuticle takes its coloration from the pigment xanthopterin, and it turns out that xanthopterin has the ability to change light into electrical energy. In other words, the brown areas trap the light, while the yellow areas allow it to be turned into energy.

To prove their theory, the team made a dye-sensitized solar cell, which used xanthopterin as a light-harvesting molecule. While it only had a conversion efficiency of 0.335 percent, it still did work, and could pave the way for further advances in the field.

The research was recently published in the journal Naturwissenschaften.

Via BBC Earth News

12 comments
Facebook User
... but how does the hornet use the electricity to power its activity?
DaddyHoggy
@Facebook User - better explanation given on the BBC website of the same story: http://news.bbc.co.uk/earth/hi/earth_news/newsid_9254000/9254445.stm
donwine
This article reminds me of a scripture in the Bible @ Psalms 104:24
Adrian Akau
Is it not the heat from the sunlight which may increase the activity of the wasp since the wasp is as cold blooded as a reptile? Perhaps the wasp uses the electricity in some other way. such as in sensing.
Željko Zike
No, this doesn\'t remind me of Psalm 104:24. God has nothing to do with this. I\'m glad that nature, not scripture, inspires scientists to move forward and think of benefits for human kind.
Matt Rings
@?eljko: chill, please. Be a bit more gracious and accepting of other cultures and beliefs. It\'s a small planet and we all have to get along...and it starts with you and me. You may not agree, but let\'s keep it civil.
alcalde
It\'s not about agreeing or disagreeing - it\'s about right and wrong. There was nothing insulting or uncivil in elijko\'s response anyway. Hijacking a comment thread about photovoltaic wasps to promote a Bible verse that denies evolution was impolite proselytizing, however.
opn4bzns
eljko and alcaide are both Evolutionary knuckle dragging insensitive morons. The Bible was written by Born Again Christians for Born Again Christians to read. You can\'t understand it because you are reading someone else\'s mail...it wasn\'t written to you, but to me and millions of other Born Again Christians who do understand it. So back off and spew your hate and venom somewhere else. Between eljko and alcaide you both together may have the brain pan of a half wit...if you can look around at the earth and universe and believe the evolution lie that it all came from NOTHING...then you are truly a product of our now Godless Socialist State run school system. One day you will meet Jesus face to face and you better be ready before that happens. Thanks donwine...that was a good verse to describe this interesting Hornet story.
Anumakonda Jagadeesh
Yet another innovative adoption of Biomimicking. Dr.A.Jagadeesh Nellore(AP),India
Racqia Dvorak
from above linked BBC article: \"\"We assume that some of the energy is transformed in a photo-biochemical process which aids the hornets with their energy demanding digging activity,\" Dr Plotkin told the BBC. The solar-powered hornets have one further unique claim. Until now, insects were thought to perform metabolism in an organ known as the fat body, which performs a similar function to the human liver. Most of the fat body is in an insect\'s abdomen surrounding the gut, where it can quickly take up absorbed nutrients, though some is scattered elsewhere. \"We have found that the main metabolic activity in the Oriental hornet is actually in the yellow pigment layer,\" says Dr Plotkin. \"