Quick self-assembly of bio-inspired multi-dimensional well-ordered structures induced by ultrasonic wave energy.

Bottom-up self-assembly of components, inspired by hierarchically self-regulating aggregation of small subunits observed in nature, provides a strategy for constructing two- or three-dimensional intriguing biomimetic materials via the spontaneous combination of discrete building blocks. Herein, we report the methods of ultrasonic wave energy-assisted, fast, two- and three-dimensional mesoscale well-ordered self-assembly of microfabricated building blocks (100 μm in size). Mechanical vibration energy-driven self-assembly of microplatelets at the water-air interface of inverted water droplets is demonstrated, and the real-time formation process of the patterned structure is dynamically explored. 40 kHz ultrasonic wave is transferred into microplatelets suspended in a water environment to drive the self-assembly of predesigned well-ordered structures. Two-dimensional self-assembly of microplatelets inside the water phase with a large patterned area is achieved. Stable three-dimensional multi-layered self-assembled structures are quickly formed at the air-water interface. These demonstrations aim to open distinctive and effective ways for new two-dimensional surface coating technology with autonomous organization strategy, and three-dimensional complex hierarchical architectures built by the bottom-up method and commonly found in nature (such as nacre, bone or enamel, etc.).