November 6, 2011 | David F. Coppedge

Engineers Tip Hat to Nature

It’s conventional in blogging to give an HT (hat tip) to a friend who makes you aware of a cool item.  Engineers are giving hat tips to plants and animals as they seek for amazing new products that do wonderful things, just like the ones in nature.

1.  Woodpecker helmets: As mentioned in our 10/27/2011 entry, scientists in China are learning how to make smarter helmets by studying woodpeckers.  The birds use a combination of features to avoid concussions.  Source: PhysOrg.

2.  Cornea hierarchical assembly:  An interesting paper in Nature last month discussed how scientists at Lawrence Berkeley National Labs are making progress imitating life’s ability to construct strong, lightweight nanomaterials that self-assemble.  Here’s a teaser from the abstract:

In nature, helical macromolecules such as collagen, chitin and cellulose are critical to the morphogenesis and functionality of various hierarchically structured materials. During tissue formation, these chiral macromolecules are secreted and undergo self-templating assembly, a process whereby multiple kinetic factors influence the assembly of the incoming building blocks to produce non-equilibrium structures. A single macromolecule can form diverse functional structures when self-templated under different conditions. Collagen type I, for instance, forms transparent corneal tissues from orthogonally aligned nematic fibres, distinctively coloured skin tissues from cholesteric phase fibre bundles, and mineralized tissues from hierarchically organized fibres. Nature’s self-templated materials surpass the functional and structural complexity achievable by current top-down and bottom-up fabrication methods.

That’s the front of your eye, the skin on the back of your hand, and teeth – all constructed by your body, using a method these scientists drool after.  “Here we demonstrate the biomimetic, self-templating assembly of chiral colloidal particles (M13 phage) into functional materials,” they boasted of their baby steps.  They had to start with viral particles that are already chiral, because it is very difficult to make chiral building blocks from scratch.  The abstract ended, “Our assembly approach provides insight into the complexities of hierarchical assembly in nature and could be expanded to other chiral molecules to engineer sophisticated functional helical-twisted structures.”  (Chung et al., “Biomimetic self-templating supramolecular structures,” Nature 478, 20 October 2011, pp. 364–368, doi:10.1038/nature10513).

3.  Venus flytrap robotPhysOrg described a mechanical Venus flytrap created by Mohsen Shahinpoor at the University of Maine.  The article includes a schematic, including trigger hairs.  Shahinpoor published his invention in Bioinspiration and Biomimetics.  His invention progresses past South Korean implementations that use shape-memory materials, according to New Scientist.  Plus, it could be coupled with “Ecobot, a robot that can digest insects, food scraps and sewage to power itself,” developed by Bristol Robotics Lab in the UK, meaning no power supply would be required.  If they can get it to grow seeds they’ll really be onto something.

4.  Gecko tank climber:  In Smart Materials and Structures, scientists gave a hat tip to the gecko again.  They created a robot that can climb smooth surfaces, like glass and porcelain, using a belt drive mechanism studded with mushroom-cap shapes that can employ weak Van der Waals forces like the spatulae on gecko feet.  In addition, it can sense its surroundings and change directions. The article on PhysOrg has pictures of the robot in action.

5.  Insect tape:  Using a similar principle to gecko-foot adhesion, scientists at the University of Kiel in Germany have made a biologically-inspired tape, reported PhysOrg. Here are some amazing sales spiels about it:

They found the patterned tape was at least two times harder to pull off of a surface than a flat tape of the same material. The insect inspired tape can also work under water, leaves behind no sticky residues, and can be attached and detached for thousands of cycles without losing its ability to grip. One team member even succeeded in dangling himself from the ceiling using a 20 x 20 centimeter square piece of the new tape.

SpiderMan is here, thanks to insect inspiration.  The last paragraph is a good general ad for biomimetics:

Bioinspired adhesives have many potential commercial applications, from wall-climbing search robots to industrial pick-and-place machines. And the research group hasn’t stopped looking to nature for new inspirations. The team is currently investigating a number of other natural surfaces, including beetle coverwings, snake skin, and anti-adhesive plants. “From nature we can get rather unconventional ideas,” says Gorb. “Not all solutions from nature are doable and not all of them are cheap. But they are numerous.”

6.  Engineered photosynthesis:  A driving force behind the study of photosynthesis is the desire to imitate it.  PhysOrg reported on work at Indiana University to study the process in cyanobacteria, so-called “primitive” microbes whose mastery of light harvesting is responsible for half the oxygen on Earth.  What can we expect from understanding it?  For starters, the “potential for increasing agricultural yields, making bio-solar energy production more feasible, and improving understanding of a globally important biological process that is vital for providing the energy needed to sustain virtually all life on Earth,” the article said. One of the cyanobacteria studied has 10,000 genes, compared to 25,000 to 30,000 in humans.

7.  More engineered photosynthesis:  A team from MIT reported the invention of “Wireless Solar Water Splitting Using Silicon-Based Semiconductors and Earth-Abundant Catalysts.”  Publishing in Science, Reece et al. began their paper talking about how plants harvest light in language that sounds like an engineer’s description.  And they did talk about evolution – but in a completely non-Darwinian sense of the word, speaking of how “oxygen evolved from the illuminated anode” of their instrument.  Their abstract ended with a hat tip to plants: “The devices described here carry out the solar-driven water-splitting reaction at efficiencies of 4.7% for a wired configuration and 2.5% for a wireless configuration when illuminated with 1 sun (100 milliwatts per square centimeter) of air mass 1.5 simulated sunlight. Fuel-forming catalysts interfaced with light-harvesting semiconductors afford a pathway to direct solar-to-fuels conversion that captures many of the basic functional elements of a leaf.”  Source: Reece et al., “Wireless Solar Water Splitting Using Silicon-Based Semiconductors and Earth-Abundant Catalysts,” Science, 4 November 2011: vol. 334 no. 6056 pp. 645-648, doi.10.1126/science.1209816.

As usual, not a single one of these fascinating science projects mentioned evolution in the Darwinian sense.  Go biomimetics!

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