Soft three-dimensional network materials with rational bio-mimetic designs

Dongjia Yan,Yihui Zhang,Hang Zhang,Jiahui Chang,Zhaoguo Xue,Jianxing Liu,Fan Zhang,Honglie Song

doi:10.1038/s41467-020-14996-5

Abstract

Many biological tissues offer J-shaped stress–strain responses, since their microstructures exhibit a three-dimensional (3D) network construction of curvy filamentary structures that lead to a bending-to-stretching transition of the deformation mode under an external tension. The development of artificial 3D soft materials and device systems that can reproduce the nonlinear, anisotropic mechanical properties of biological tissues remains challenging. Here we report a class of soft 3D network materials that can offer defect-insensitive, nonlinear mechanical responses closely matched with those of biological tissues. This material system exploits a lattice configuration with different 3D topologies, where 3D helical microstructures that connect the lattice nodes serve as building blocks of the network. By tailoring geometries of helical microstructures or lattice topologies, a wide range of desired anisotropic J-shaped stress–strain curves can be achieved. Demonstrative applications of the developed conducting 3D network materials with bio-mimetic mechanical properties suggest potential uses in flexible bio-integrated devices.

Highlights

Many biological tissues offer J-shaped stress–strain responses, since their microstructures exhibit a three-dimensional (3D) network construction of curvy filamentary structures that lead to a bending-to-stretching transition of the deformation mode under an external tension
Many collagenous tissues are found to possess a type of helixshaped 3D microstructures[2,43,55,56], some of which exhibit regular geometric configurations. These helix-shaped 3D microstructures are crucial to the J-shaped stress–strain responses[57,58,59,60]. Inspired by this type of 3D helical microstructures, we introduce a biomimetic design of soft 3D network materials based on periodic 3D lattice configurations, in which periodically arranged helical microstructures serve as building blocks that connect the lattice nodes
Inspired by the network constructions and helical microstructures of many collagenous tissues, we develop a 3D network design by exploiting a type of 3D helical microstructures as the building blocks that are extended with different 3D lattice topologies

Summary

Introduction

Many biological tissues offer J-shaped stress–strain responses, since their microstructures exhibit a three-dimensional (3D) network construction of curvy filamentary structures that lead to a bending-to-stretching transition of the deformation mode under an external tension. We report a class of soft 3D network materials that can offer defect-insensitive, nonlinear mechanical responses closely matched with those of biological tissues This material system exploits a lattice configuration with different 3D topologies, where 3D helical microstructures that connect the lattice nodes serve as building blocks of the network. For two-dimensional (2D) biological tissues (e.g., skin47), a soft network design that incorporates horseshoe microstructures into periodic lattice constructions has been developed, which can be tailored precisely to match the J-shaped stress–strain curves of human skins at diverse locations[48,49] This type of 2D network design cannot be extended directly to three-dimensional (3D) cases, due to the 2D nature of horseshoe microstructures. Integration of conducting layers with soft 3D network materials allows the development of flexible pressure sensors and stretchable conductors with J-shaped stress–strain curves matched with that of biological tissues, indicating the potential applications in biomedical devices

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Results

Conclusion