The Genius of the Spider
February 4, 2010
Fog-catching nets which provide precious water in rain-starved parts of the world may be poised for a high-tech upgrade thanks to the spider.
In a paper published in the journal Nature on Wednesday, Chinese scientists report on why spider’s silk is not only famous for strength but also terrific for collecting water from the air, sparing the creature a hunt for a drink.
The secret, revealed by scanning electron microscope, lies in the silk’s tail-shaped protein fibres which change structure in response to water.
Once in contact with humidity, tiny sections of the thread scrunge up into knots, whose randomly arranged nano-fibres provide a roughly, knobbly texture.
In between these “spindle knots” are joints, which are smooth and slender, comprising neatly aligned fibres.
Small droplets then condense randomly on the spider’s web. Once they reach a critical size, the droplets slide along the slick-surfaced joints thanks to surface tension.
The droplets then reach the spindle knots, where they coalesce with larger drops.
As a result, the joints are freed up to begin a new cycle of condensation and water collection.
…The breakthrough will help the development of man-made fibres that will help water collection and could also be used in manufacturing processes to snare airborne droplets, they believe.
Fog collection entails stretching out nets or canvas on poles and using the mesh to catch moisture from the breeze. The runoff is collected in a pipe or a trough on the ground.
The technique, pioneered in the coastal Andes, is being encouraged in poor, dry parts of the world, such as Nepal. It is also being promoted by charities as a useful tool to offset water stress caused by global warming.
February 4, 2010 at 3:50 pm
While in some parts of the world people are going to great lengths to obtain enough water to keep them alive, elsewhere the precious commodity is being wasted in a profligate manner. Last night the BBC had a programme with the unpromising name Jimmy’s Supermarket Secrets. It was about food production and distribution and highlighted a vast expanse of Egyptian desert being watered from a well 350 metres down which was gradually being exhausted. The potatoes were packed in peat imported from Ireland then exported in containers to the United Kingdom. The whole process seemed wrong in so many ways.