Characterization of the microscopic tribological properties of sandfish (Scincus scincus) scales by atomic force microscopy.

Weibin Wu,Simon Mersch,Guillaume Gomard,Christian Lutz,Richard Thelen,Christian Greiner,Hendrik Hölscher

doi:10.3762/bjnano.9.243

Weibin Wu, Simon Mersch + Show 5 more

Open Access

https://doi.org/10.3762/bjnano.9.243

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Abstract

Lizards of the genus Scincus are widely known under the common name sandfish due to their ability to swim in loose, aeolian sand. Some studies report that this fascinating property of sandfish is accompanied by unique tribological properties of their skin such as ultra-low adhesion, friction and wear. The majority of these reports, however, is based on experiments conducted with a non-standard granular tribometer. Here, we characterise microscopic adhesion, friction and wear of single sandfish scales by atomic force microscopy. The analysis of frictional properties with different types of probes (sharp silicon tips, spherical glass tips and sand debris) demonstrates that the tribological properties of sandfish scales on the microscale are not exceptional if compared to snake scales or technical surfaces such as aluminium, Teflon, or highly oriented pyrolytic graphite.

Highlights

Areas with loose, aeolian sand in the deserts of North Africa and the Arabian Peninsula are the habitat of the lizard Scincus scincus [1]
In order to probe whether the results presented above and obtained by atomic force microscopy are a result of the inherent nanoscale nature of these experiments, or if they can be generalized to larger-contact scenarios, additional friction measurements with a reciprocating ball-on-plate microtribometer were conducted
The frictional coefficient measured with a sharp tip on a sandfish scale is interestingly lower than that on technical materials such as Teflon, poly(methyl methacrylate) (PMMA) or silicon but still larger than that on a common dry lubricant such as HOPG or a psammophile snake like S. diadema

Summary

Introduction

Aeolian sand in the deserts of North Africa and the Arabian Peninsula are the habitat of the lizard Scincus scincus [1] (see Figure 1a). Using different types of AFM probes we do not observe favourable frictional properties of sandfish scales if compared to technical surfaces with tribological relevance. Analyse the topography, adhesion, frictional coefficient, and wear resistance of sandfish scale by atomic force microscopy applying several types of probe shape and material.

Results

Conclusion