Study on the structural parameters and adhesive force of gecko seta

ABSTRACT

It is found from the observation that seta on the adhesive pad of gecko is around several microns in diameter and has a multilevel projective terminal which eventually forms 100 ~ 1000 projections. In addition, the adhesive force of a single seta is about 20 ~ 200μN. To explain this fine structure and such a large adhesive force of seta, we develop an ideal-self-similar hierarchical model composed of a fiber array at each level to mimic the multilevel projective terminal of single gecko’s seta. With this model, the variations of the properties with increasing number of levels are investigated. For Tokay gecko’s seta, the total number of levels is first estimated, and the structural parameters such as radius, the total number of terminal fibers and the adhesive force are then predicted. The results agree well with those observed in nature. Furthermore, with the present model, the dominant failure mode of each level is always the adhesion failure, and the role of structural hierarchy for adhesion release is addressed.

KEYWORDS:

• Biomechanics
• hierarchical material
• ideal-self-similarity
• fiber array
• flaw tolerant adhesion
• seta

Acknowledgements

This work was supported by the National Natural Science Foundation of China (Grant Nos. 11672221, 11272245). The authors would like to thank the reviewers for their helpful comments and suggestions.