Biological and bioinspired Bouligand structural materials: Recent advances and perspectives

Bouligand structure lays the mechanical foundations for the survival of many organisms. Decoding and transcribing the biological Bouligand structure into synthetic materials is promising for boosting the development of advanced fiber-based structural materials, which has attracted considerable attention in recent years. In this review, we first analyze the basic elements of biological Bouligand structure and classify this structure based on diverse biological tissues. We then representatively introduce multiscale and multimodal characterization techniques that are implemented to decode biological Bouligand structural materials. Based on the understanding of biological Bouligand structure's design principles and implications, we further present multiple fiber assembly strategies for bioinspired Bouligand structural design and discuss their differences. Moreover, the Bouligand-structure-induced applications are illustrated. Finally, the challenges and perspectives on the development of bioinspired Bouligand structure are proposed. We hope to spur continuous efforts and innovations concerning bioinspired Bouligand structural materials to enable their wide application in different technical fields.