Paris | Thursday
REFUGEES and farmers struggling to survive in a parched climate may one day bless a Namibian desert beetle which collects droplets of fog on its back in order to survive.
The tenebrionid beetle thrives in one of the most hellish places on Earth thanks to microscopic bumps and troughs on its back, which pick up the airborne droplets and then channel them to its mouth.
Oxford University zoologist Andrew Parker and mechanical scientist Chris Lawrence of QinetiQ, a space and technology spinoff from Britain’s ministry of defence, say they have now figured out the beetle’s secret.
The peaks of the bumps are smooth but non-waxy, which causes water molecules from fog to stick there.
The molecules build up into a droplet that rolls down into one of the tiny troughs, which are coated with a waxy substance that repels water.
Eventually, the droplet fills up the trough, at which point the capillary force that attaches it to the trough’s surface is overcome. The droplet then detaches from the trough and starts to roll down the beetle’s sloped back towards its mouth.
The beetle — formally known in Latin as Stenocara — is part of the unique sand-dune fauna of the Namibian desert, able to withstand high winds, scorching daytime temperatures and rainfall so low and variable as to be classified as negligible.
Its only dependable source of water is dense, early-morning fog.
Parker and Lawrence drew up an equation that showed the little critter had got its bumps and troughs just the right size – as little as 0.5 millionths of a metre across.
That enables it to collect the precious droplets on its back and not lose any through wind or heat.
The discovery has a fantastic potential for providing water for people or farm animals in dry or marginal climates, say Parker and Lawrence.
Beetle-backed plastic sheeting could provide a water-trapping material for a tent or the side of a building.
”The Stenocara structure can easily be reproduced in sheet form by injection-moulding or printing techniques, allowing a variety of uncooled devices to be produced for controlling collection of vapour, including water for drinking or farming inhospitable regions,” they say.
Their research is published on Thursday in Nature, the British science weekly. – Sapa-AFP