Robust substrate anchorages of silk lines with extensible nano-fibres

TL;DR

This study investigates how spider silk nano-fibres assemble into micro-structures that enhance mechanical robustness, providing insights for designing biomimetic high-performance attachment systems.

Contribution

It reveals the assembly principles of spider silk nano-fibres that lead to robust substrate anchorage, informing biomimetic material design.

Findings

Orb weaver anchors show high mechanical robustness with minimal material.

Assembly of silk nano-fibres involves indirect attachment via a soft 'bridge' domain.

The principles can inspire artificial high-performance attachment systems.

Abstract

Living systems are built of multiscale-composites: materials formed of components with different properties that are assembled in complex micro- and nano-structures. Such biological multiscale-composites often show outstanding physical properties that are unachieved by artificial materials. A major scientific goal is thus to understand the assembly processes and the relationship between structure and function in order to reproduce them in a new generation of biomimetic high-performance materials. Here, we tested how the assembly of spider silk nano-fibres (i.e. glue coated 0.5 micron thick fibres produced by so-called piriform glands) into different micro-structures correlates with mechanical performance by empirically and numerically exploring the mechanical behaviour of line anchors in an orb weaver, a hunting spider and two ancient web builders. We demonstrate that the anchors of orb weavers exhibit outstanding mechanical robustness with minimal material use by the indirect attachment of the silk line to the substrate through a soft domain ('bridge'). This principle can be used to design new artificial high-performance attachment systems.