Dragonfly wings inspire new generation of aerogels

Scientists have created a new form of highly-efficient, low-cost insulation material based on the wings of a dragonfly.

Aerogel is the most porous material known to man and ultralight, with a piece the size of a family car weighing less than a kilogramme, said Lidija Siller from the Newcastle University in the UK. Starting out as a wet silica gel, similar in structure to jelly, the material is carefully dried to create a strong, porous material, said Siller, joint lead author of the research published in the journal Advanced Materials.

However, until now, removing the water molecules without collapsing the fine silica structure has been a long, difficult and expensive process and as a consequence, the use of aerogels has been limited to a few highly specialist tasks, such as the collection of stardust in space. Now, a team of experts has managed to cheaply replicate the process by mimicking the way in which the dragonfly dries out its wings. Instead of drying the silica under high temperature and pressure, the team used bicarbonate of soda (the same used to make cakes rise) to 'blow' out the water molecules, trapping carbon dioxide gas in the pores.

The next step will be to scale up the process to create larger panels that can be used to insulate our homes and buildings, researchers said.

"The potential of this discovery in terms of reducing energy use and therefore our energy bills is really exciting," said Siller.

"Aerogels are an amazing material - safe, light and ten times more insulating than what we are using now - but until now they have been out of reach for the majority of us because they are so expensive to make. Our research is a step towards making them widely available," Siller said. Dragonflies belong to the insect order known as Odonata, meaning "toothed jaw" due to their serrated mouthparts.

"These ancient insects were around long before the dinosaurs evolved," said Dejan Kulijer from the National Museum of Bosnia and Herzegovina.

Their wings are a porous, layered structure similar to an aerogel and are so strong and light they can carry the insect up to 30 miles in an hour. "A dragonfly's wings are an ultralight aerogel - making up less than 2 per cent of the insect's total body weight - and yet they are so strong they can carry the insect thousands of miles across oceans and between continents," said Siller.

Their bodies produce bicarbonate molecules which release carbon dioxide gas that regulates body pressure and dries wings at the same time. This 'blows' out the water to leave a dry, stable, light and strong structure. "We replicated this process in the lab with the aerogel, blowing out the water at ambient temperature and with sodium bicarbonate," Siller said.

 

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