The multi-frequency vibration metastructure for three-dimensional containerless attractor of particles

Constructing morphologies of particles is essential for material, biomedical, and chemical handling. Conventionally, the ordered morphologies are constructed either by internal or external force, such as optical, magnetic, electrical, and acoustic field. Existing manipulation of particles has been limited to the two-dimensional patterns due to gravity. It is challenging to construct various three-dimensional morphologies of particles. In this work, the multi-frequency vibration metastructure design for three-dimensional morphologies manipulation of particles is investigated. Tunable containerless morphologies are further achieved by altering the vibration modes of the metastructure. Firstly, the programmable vibration modes are realized by the vibration metastructure. Tunable vibration modes are generated through switching the excitation frequencies for the resonant labyrinth-type structures at different directions. Then, the three-dimensional morphologies of particles are realized near the vibration anti-node. Particles are driven by the high-intensity acoustic field, wherein gravity is overcome, including the combined effect of acoustic streaming, acoustic radiation force, and collision force. Further, the trapping of granular particles exhibits multiple morphologies assemblages with tunable height, rotation, and dynamic oscillation through parametric excitation. Finally, the directions of various attractor walls can be tunable by demultiplexing the multi-frequency vibration metastructure. This work paves a way for control of vibration modes by the metastructure, thereby enabling tunable three-dimensional morphologies manipulation of particles.