Snake skin-inspired steel could lead to better hard drives

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Bio-inspired scale-like surface morphology akin to a python(Credit: Christian Greiner, KIT)

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When it comes to human phobias, snakes are frequently found toward the top of the list. But despite the negative reputation, these reptiles make up an important part of our ecosystem while exhibiting some very unique biological aspects. The way snakes move across surfaces is pretty incredible, and researchers at the Karlsruhe Institute of Technology (KIT) have figured out how to potentially use that feature to enhance everything from hip prostheses to computer hard disks.

The study of snakes has given rise to better robot locomotion in sand and autonomous vehicle recharging. And now, the physics of snake scales may help to reduce friction and wear in mechanical systems.

Together with Michael Schäfer, Greiner developed a process to transfer the scale structure of reptiles to components of electromechanical systems: With a fiber laser, they milled scales into a steel bolt of 8 mm in diameter.

By generating friction at specific points, a snake is able to create forward movement with minimal wear on its scales. With that in mind, researchers at KIT milled scales into a steel bolt 8 mm in diameter using a fiber laser. This scale-like texturing was then tested to see if it allowed for lower friction forces versus untextured surfaces. One laser-etched design was inspired by the narrow, overlapping scales of a python. The other design had scales arranged in wider-spaced, vertical rows, similar to that of a sand skink lizard. Both designs were tested on lubricated (steel) and unlubricated (sapphire) contacts.

For lubricated conditions, the untextured surface generated the least amount of friction while the textured surfaces had an increase of friction by a factor of 1.6 (wide/lizard) and 3.0 (narrow/python). Under dry, unlubricated conditions, the untextured surface showed the highest amount of friction while the textured surfaces reduced friction. In both cases, there was a significant performance difference between the narrow and wide texture patterns.

The researchers had anticipated that the narrow (python) texture would have been more beneficial, since it was closer to the natural animal inspiration. Further experimentation is planned to test how the size of the scales and the hardness of the material effects the friction of the bolt.

Although it wasn't the primary focus of the research, the amount of surface-wear was evaluated by the team. Since extremely little wear was observed, even with hard materials like steel and sapphire, it shows that scale-like texturing has potential application for dry-contact devices and/or environments that benefit from low friction and high wear resistance.

A paper on the research was recently published in the journal Bioinspiration & Biomimetics.

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