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Wednesday, 31 October, 2001, 19:10 GMT
Water off a beetle's back
Nature/Oxford Univ/QinetiQ
The beetle thrives in one of the driest places on Earth
Helen Briggs

A beetle that survives in the desert by trapping drinking water on its back could help arid nations.

By mimicking the creature's hydrological tricks-of-the-trade, British scientists have developed unique water-collecting materials.

The beetle-backed plastic sheeting provides an alternative to vertical netting used to harvest water from fog in parts of South America and the coast of west Africa.

The technology might also be used in distillation processes, dehumidifiers and even in car engines.

Nature's example

The idea came from a beetle that is able to capture minute water droplets from early-morning fog using a special surface on its back.

Nambia, BBC
Namibia: Rain seldom falls
Microscopic bumps and troughs condense water from the air and channel it down to the beetle's mouthparts.

This enables the creature to live in southern Africa's Namib Desert, one of the harshest environments on Earth.

Dr Chris Lawrence of research company QinetiQ, a spin-off from the UK's Ministry of Defence, told BBC News Online: "What we have learnt from the beetle is an improved method for condensing liquid from a vapour.

"We're intending that this will be applied to the collection of water for farming and drinking in arid regions, improvement in distillation processes and dehumidification for air conditioning and the like."

Hot and dry

The Namib Desert is a wilderness that stretches southwards from southern Angola to South Africa across Namibia.

High winds and extreme temperatures prevail during the daytime but rain hardly ever falls.

In the early morning, a dense fog blows in from the Atlantic. This fog contains droplets of water vapour, which the beetle, a member of the tenebrinoid family, has evolved a natural mechanism to capture.

The beetle has a bumpy surface on its back. The troughs are coated with wax, which makes them water-repelling (hydrophobic). But the peaks are non-greasy and water loving (hydrophilic).

When a sea breeze blows over, the beetle leans into the wind.

Tiny droplets of water are attracted to the hydrophilic peaks, where they build up into larger drops, which eventually roll down the beetle's back towards its mouth.

Thus, the beetle has a ready source of drinking water even though it seldom rains.

Desert camping

The Farnborough-based company has developed a unique beetle-backed material in collaboration with Dr Andrew Parker, a zoologist at Oxford University, UK, who studied the beetle.

By embedding tiny glass spheres in warm wax, they created a similar pattern of water-attracting peaks and water-repelling troughs.

Tests showed that water formed on the sheets, when they were sprayed with a fine mist. The material can be easily reproduced on a larger scale by stamping peaks and troughs into plastic sheeting.

The pair envisage several commercial applications for the material.

Attached to roofs, it could be used as an alternative to the vertical netting used to capture water in arid countries.

"This would make fog harvesting several times more efficient than current water collecting methods," Dr Parker told BBC News Online.

The first application, he said, would be a pattern screen-printed on to tents to enable desert campers to collect their own drinking water.

The research is published in the journal Nature.

See also:

14 Nov 00 | Sci/Tech
'Pot' beetle gets helping hand
16 Jul 00 | Sci/Tech
Biting beetle gives away secrets
17 Aug 99 | Sci/Tech
Bull's-eye beetle
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