10.1021/acs.nanolett.8b00828.s003 Ziao Tian Ziao Tian Wen Huang Wen Huang Borui Xu Borui Xu Xiuling Li Xiuling Li YongFeng Mei YongFeng Mei Anisotropic Rolling and Controlled Chirality of Nanocrystalline Diamond Nanomembranes toward Biomimetic Helical Frameworks American Chemical Society 2018 material helical microscale actuation FEM 3 D design VO 2 Cr technology application diamond-based helical framework Nanocrystalline Diamond Nanomembranes Biomimetic Helical Frameworks Future advances model 2018-05-25 14:04:04 Media https://acs.figshare.com/articles/media/Anisotropic_Rolling_and_Controlled_Chirality_of_Nanocrystalline_Diamond_Nanomembranes_toward_Biomimetic_Helical_Frameworks/6356387 Future advances in materials will be aided by improved dimensional control in fabrication of 3D hierarchical structures. Self-rolling technology provides additional degrees of freedom in 3D design by enabling an arbitrary rolling direction with controllable curvature. Here, we demonstrate that deterministic helical structures with variable rolling directions can be formed through releasing a strained nanomembrane patterned in a “utility knife” shape. The asymmetry of the membrane shape provides anisotropic driving force generated by the disparity between the etching rates along different sides in this asymmetric shape. A transient finite element method (FEM) model of diagonal rolling is established to analyze the relationships among geometries, elastic properties, and boundary conditions. On the basis of this model, a diamond-based helical framework consisting of two or three helical segments has been fabricated to mimic the shapes of natural plants. Further experiment has been done to extend this approach to other materials and material combinations, such as MoSe<sub>2</sub>/Cr, Cr/Pt, and VO<sub>2</sub>. To demonstrate the possible application accessible by our technology to new fields, VO<sub>2</sub>-based helical microscale actuation has been demonstrated with photocontrollable bending in a selected region, as well as morphable and recognizable helix. This study offers a new way to construct helical mesostructures that combine special properties of the advanced materials, thus possess novel features and potential applications.