December 3, 2009 | David F. Coppedge

Taking Inspiration from Nature

In the previous entry, Darwin inspired some geologists, even though he was wrong.  Here are some news stories showing nature inspiring engineers with wonders right under their noses.

  1. Aerodynamic seed:  A plant in Java has seeds that are perfect gliders.  The BBC News said of the Alsomitra vine: “The seeds, which are produced by a football-sized pod, can glide hundreds of metres across the forest.”  The seeds, among the largest for any winged seed, weigh 300 grams but are supported by wings just 1mm thick.  “The aerodynamics of the giant Alsomitra seeds were studied by two Japanese engineers, Akira Azuma and Yoshinori Okuno more than 20 years ago,” the report said.  “They found that design of the seed is so good that it achieves a descent angle of just 12 degrees, a property that has led to the seed’s shape inspiring the design of aircraft.”  The article includes a video of the seeds emerging from their pod and flying like a squadron of gliders around the forest.
  2. Digging clam:  Inspired by how clams dig into the sand, MIT engineers built “RoboClam,” a device that imitates its living counterpart.  Live Science reported that the device could be used to detonate underwater mines.  The razor clam “can burrow into the bottom of its native mudflats at a remarkable rate of roughly a centimeter per second” because “The clam digs with two motions – a push upwards with its foot, which mixes the mud grains with the liquid above, and a synchronized push down.  This motion creates a liquid-like quicksand layer around its body, reducing the drag from burrowing and dramatically reducing the overall energy used.”  So “Inspired by this principle,” the engineers built RoboClam.  It works.  It’s small, lightweight, and uses low energy.  “The thing that surprised me most is how robust the digging mechanism is,” one team member said.  Devices using this principle might also help underwater installations, like cables, secure themselves once hitting bottom, and easily detach themselves when the equipment needs to be recovered.
  3. Solar lotus:  The “lotus effect” (reported earlier, see 09/23/2009) might improve the efficiency of solar cells by as much as 25%, New Scientist reported.  More light could get into the detectors by installing miniature domes at the nano scale, scientists at Stanford are finding.  This reduces stray reflections and ensures more photons reach the detector.  Another benefit will be the ability to repel water and dirt, just like on the lotus leaf.  “Water droplets landing on the leaf cannot achieve a contact angle that breaks their surface tension, so they form beads on the leaves rather than wetting them,” the article said.  In the same way water drops will roll off the surface of the nanodome solar panel taking any light-blocking dust with them.”  A related story was reported by PhysOrg about researchers using peptides to produce a water-repellant surface.  Your future may include self-cleaning windows.

These and many other promising technologies are emerging from biomimetics – the imitation of biology.  Sometimes the technologies are not seen beforehand.  Scientists in Germany, for instance, are studying how diatoms build their glass shells.  PhysOrg reported that they discovered the single-celled organisms use a network of chitin as a scaffolding.  No human application was mentioned, but one can envision nanoengineering taking advantage of a similar principle to build durable materials at the molecular scale just like the diatom does so well.
Update 12/04/2009: “Stealing from nature” is the theme of a lengthy article on biomimetics on PhysOrg, “Nature’s fine designs: Scientists find modern lessons in ancient creations.”  Aside from frequent personification of nature and unnecessary references to billions of years, the article contains some stunning information about natural biotechnology.  Example: “From a substrate of single crystals, the brittle star can grow lenslike spherical arrays that are on the micron-scale, pass light without distortion, focus light exceptionally, and as a bonus are terrifically strong mechanically.  (Because of the brittle star, we now have bio-inspired arrays of tunable micro-lenses.)”  For more on brittle star lenses, see 08/23/2001.

Won’t you be glad when the Year of Darwin is over and we can focus once again on the good stuff that is inspiring and useful.

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