Lizard skins and bark bugs inspire energy saving materials

Biomimicry, also called bionics, uses structures found in nature to solve everyday problems. A well-known example is the Velcro strip, which a Swiss engineer, Georges de Mestral, copied from the burdocks that stuck to his dog and clothes on a walk through the fields. With modern instruments like the electron microscope, scientists can reveal how nature has cleverly solved many well-known engineering problems: how can the gecko walk on ceilings? How can the water strider walk on water?

Researchers are now looking at the next generation of questions, particularly in animals’ skins where extraordinary properties are found. How do lizards living in extremely dry environments collect dew through their skins? How do flat bark bugs darken when wetted? Whatever microstructures govern these processes could be very useful for solving everyday engineering problems, such as the quest for lubrication to minimise resistance (and hence wasted energy) that could transform the energetic efficiency of millions of machines.

This is the object of the European project LiNaBioFluid. Scientists first examined the structures of the lizard and bark bug skins using electron microscopy. They then took micro pictures of these surfaces, analysing the characteristics that might render them their extraordinary properties. Finally, these structures were duplicated using advanced laser technology on hard inorganic materials like silicon, steel, bronze and titanium alloys, and their friction-reduction and other properties put to the test.

In friction reduction, the team made use of a well-known principle in biomimicry: at the micro scale, cleverly roughened surfaces have less friction than perfectly smooth surfaces (think of the record breaking sharkskin swimsuits that were banned from competition in 2009 for being too effective).



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