On bioinspired 4d printing: materials, design and potential applications

The emerging four-dimensional (4D) additive manufacturing (AM) has evolved from passive 3D printed objects to active ones, where materials and structures react to environmental stimulus. While nature is often the inspiration in fabricating static structures, it also plays a vital role in 4D printing. In order to survive and protect themselves from harsh environments, both plants and animals are equipped with unique movements and locomotion. However, the process of fabricating bioinspired 4D structures is complex and challenging. This review provides an overview of nature-inspired actuation to the realisation by 4D printing. Firstly, an understanding of nature actuations is briefly depicted. Next, the processes involved in the fabrication of 4D printed parts are described. Lastly, the challenges and potential applications are discussed.