Tunable Friction Properties of Periodic Wrinkled BaTiO₃ Membranes

The wrinkled patterns may find potential applications in the areas that require tunable friction properties, such as flexible electronics, nanomechanical systems, and biomedical devices. However, the regulation of wrinkled patterns and the influence of friction property remain poorly understood, especially in the field of oxides. The epitaxial wrinkled BaTiO₃ (BTO) membranes are prepared by the pulsed laser deposition and water-dissolution process. The patterns, amplitude, and wavelength of the wrinkled BTO membranes are dependent on the thickness, pre-stretched mechanical stress, and heat treatment. The friction properties of the wrinkled BTO membranes exhibit various anisotropic and periodic features due to the varying wrinkled patterns as applying different mechanical stress, including anisotropy with 180° angular periodicity, anisotropy with 360° angular periodicity, and isotropy, corresponding to the parallel, zigzag, and labyrinth patterns, respectively. Moreover, the heat process can further alter the magnitude of the friction property, showing a downward trend with increasing temperature. These results provide a better understanding of the friction properties of wrinkled patterns and pave a novel way to alter the friction properties for extensive applications.