Biological and Bio-inspired Heterogeneous Composites: From Resilient Palm Trees to Stretchable Electronics
Structural hierarchy, heterogeneity, and an adapted interfacial design are hallmarks of biological materials and have been exploited in engineering to optimize the mechanical response of composite materials used in load-bearing applications. In this chapter, we first revisit the exquisite hierarchical structure of plants, in particular the palm tree, to show how multiscale gradients provide an elegant means to optimize the stress distribution and architecture of load-bearing, resilient biological materials. We then turn our attention to synthetic heterogeneous composites that harness the concept of graded designs to enable mechanical coupling between hard and soft components of interest in the emerging field of stretchable electronics. By discussing similarities and disparities between these selected natural and artificial systems, a critical analysis on the benefits and challenges in the field of biomimetic materials research is presented. While synthetic systems remain far from reaching the level of architectural control found in natural materials, recently developed fabrication technologies provide encouraging demonstrations that suggest a promising future for biologically inspired advanced materials.