Fluid-structure boundary-driven simultaneous standard-inverse Chladni patterns for selective particles manipulation

In fluid, particles patterning and selective manipulation are essential for material, biomedical, and robotic handling. The German physicist Chladni has investigated the particles manipulation on a flat vibrating plate. Generally, particles bounce with the vibrating plate, gradually accumulate to nodal lines or anti-nodes, forming either standard or inverse Chladni patterns. The Chladni patterns show great potential for particles assembly in different environments. The mechanisms for simultaneous manipulation by multiple kinds of forces are still unclear. Here, the Chladni plate with a vertical boundary is used for selective particles manipulation. The simultaneous standard-inverse Chladni patterns are realized on the vibrating plate by modulating the frequency. First, the particles patterning mechanisms on the Chladni plate with vertical boundary are investigated for the acoustic radiation force and the acoustic streaming. The simultaneous standard-inverse Chladni patterns are realized due to the driving of vertical boundary. Then, through switching the excitation frequencies, the tunable particles patterns are realized. Finally, the selective separation of particles with different sizes and densities is investigated using the standard-inverse Chladni patterns. This work investigates the particles manipulation mechanisms on vibrating plate by the fluid-structure boundary-driven acoustic field, thereby potentially providing a platform for selective patterning and separation of particles.