Lizard skin inspires lubricant-free slipperiness
Engineers now frequently copy designs in nature—a field known as biomimetics—resulting in many great gains in our technology.1 But sometimes even the engineers themselves are surprised at just how dramatic the improvements can be.
A recent example featured in the Bioinspiration and Biomimetics journal is the copying of the scaly skin of the sandfish skink lizard (Scincus scincus).2 Engineers already knew that the shape and pattern of its non-overlapping scales make the skin ‘slippery’ when going forwards, but give it high resistance to movement in the opposite direction (thus helping the creature to propel itself forward). And they knew it was achieved without lubrication, as the skinks do not secrete oils or other liquids onto their skin.
So, wanting to see if this feature might be usefully applied in engineering, researchers Christian Greiner and Michael Schäfer of the prestigious Karlsruhe Institute of Technology (Germany) etched similar scale shapes and patterns onto flat steel using laser surface texturing. When they slid the steel across a smooth, dry sapphire surface, they were astonished to discover that the lizard-inspired etched pattern lowered friction by an amazing 40%.
“If we’d managed just a 1% reduction in friction, our engineering colleagues would have been delighted; 40% really is a leap forward and everyone is very excited!” said Greiner.3
It’s easy to see why. This discovery could help to reduce friction in machines that cannot be lubricated, e.g. miniature devices in which lubricants tend to hinder and gum up moving parts—in fact, under lubrication, this scaly structure increased friction threefold compared to a smooth surface.2 It could also be used to reduce friction in the sensors used in anti-lock braking systems and computer hard-disk drives, and in the accelerometers used in cell phones. Furthermore, preliminary results suggest that the scaly texture also reduces wear.2
With further refinement, the potential applications could include making lizard-inspired robots useful for exploring extremely dusty environments (where oily lubricants are notoriously difficult to manage and keep clean).
Of course, given the inspiration source of all these applications, one should always remember that God thought of it first! Unfortunately, the researchers instead wrongly ascribe design in nature to being “the result of a long evolutionary adaption process.”2 But how does that make any sense, given the many thousands of research hours and top-flight engineering intelligence employed in merely copying biological design—does it not rather point to there being a Designer behind it all? No wonder that the Designer inspired the Apostle Paul to write that God’s power can be perceived in the things that have been made, “so that they are without excuse” (Romans 1:20).
References and notes
- See creation.com/biomimetics. Return to text.
- Greiner, C., and Schäfer, M., Bio-inspired scale-like surface textures and their tribological properties, Bioinspiration & Biomimetics 10(4):044001, 30 June 2015. Tribology is the study of solid surfaces moving against each other, from Greek τρίβω (tribō) = rub. Return to text.
- Johnston, H., Reptile skint inspires super-slippery steel surfaces,physicsworld.com, 7 July 2015. Return to text.