具有表面起皱纹的三维多稳定结构

This paper demonstrates how two-dimensional (2D) planar films transform into three-dimensional (3D) multi-stable structures with 3D surface wrinkling patterns by means of magnetron sputtering. The wrinkling patterns on metal films deposited on polydimethylsiloxane (PDMS) elastic substrates is studied. Surface wrinkling of the Al film results from compressive thermal stresses. The effects of film thickness on the wrinkling patterns regularities are investigated. It is found that 3D labyrinth hierarchical wrinkling patterns for large sputtering flux span scale wavelengths (e.g., from nanometer to micrometer). Moreover, the hydrophobicity of the wrinkled surface has a good improvement with the contact angle. Furthermore, when bottom constraints are removed, bilayer thin films also spontaneously curl, evolving into 3D multi-stable structures with large deformations and surface patterns for releasing inner stress, which present neutrally stable configurations with no stiffness. Square multi-stable structures eventually remain stable along the diagonal as the width decreases. Simultaneously, the surface of multi-stable structures is found only labyrinth wrinkling pattern with nanoscale wavelength due to unrestraint. In addition, the finite element method was performed to simulate experimental deformation. Deformable 3D structures with multiple scales hold considerable promise for practical applications in engineering.