February 24, 2010 | David F. Coppedge

Spider Hair: The Perfect Water Repellant Surface

To keep dry, make like a spider.  “Engineering researchers have crafted a flat surface that refuses to get wet,” began a press release from University of Florida.  “Water droplets skitter across it like ball bearings tossed on ice.  The inspiration?  Not wax.  Not glass.  Not even Teflon.”  The audience waits breathlessly for the answer.  “Instead, University of Florida engineers have achieved what they label in a new paper a ‘nearly perfect hydrophobic interface’ by reproducing, on small bits of flat plastic, the shape and patterns of the minute hairs that grow on the bodies of spiders.”
    How does the spider do it?  The researchers expected to find a regular pattern on a small scale, but instead, “learned that spider hairs are both long and short and variously curved and straight, forming a surface that is anything but uniform.”  This apparently chaotic surface is key to its effectiveness.  When Wolfgang Sigmund at U of Florida imitated that, the results were perfect.  Unlike other hydrophobic materials, this one repelled the microscopic spheres of water without distorting them.  “The results came as a great surprise.”  It’s something that had to be discovered in the lab instead of by theory, he said.  “Most people that publish in this field always go for these perfect structures, and we are the first to show that the bad ones are the better ones,” Sigmund said.
    Another benefit of this finding is that it can be made from any material.  Because the trick is done with physics instead of chemistry, the hydrophobic surface manufactured to spider spec does not have to slough off any dangerous chemicals.  Sigmund is now working on similar surface tricks that can repel oil.  If engineers can figure out economical ways to manufacture these surfaces with enough durability for a range of temperatures, industry will beat a path to the spider’s web.  The spider, of course, already knows how to manufacture the material durably and flexibly, and even repair it.  Ever seen a wet spider?
    See also the 02/04/2010 for another wonder of spider water management technology.

Who taught the spider that a chaotic pattern of curved, straight, long and short hairs created the perfect water-repellant surface?  Natural selection?  Ha!  How many spiders had to drown trying to get that right.  Biomimetics is the coolest thing in biology.  It’s interdisciplinary, too: the biologists, the physicists, and the engineers can all get together.  We’re going to see a lot of neat products coming from this very un-Darwinian, ID-friendly approach.  Your spidey raincoat and lotus windshield will keep you high and dry.  You may not want this technology in your sponge, though.  (For that, mimic a natural sponge.)

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