Dynamic Assembly of Microspheres under an Ultrasound Field.

The assembly of micro-nanoparticles is one of the key tasks for controlling and manipulating the structure of materials at micro/-nanoscale. By carefully designing the ultrasound experiments and comparing the results with acoustic theories, we presented an in-depth study of the ultrasound-induced assembly behaviors of micro/-nanoparticles (microparticle size≪wavelength), especially their dynamic interactions between microparticles. The whole assembly processes including floating micro/nanoparticles, single particle communication, assembly to single particle interactions, and reorganization of assembly are fully studied. A rapid response of the ultrasound-based assembly (0.5 min) shows distinct advantages compared to those of previously used methods such as light-, electrical- and temperature-based ones. Such an efficient and effective microparticle assembly holds great promise for fabrication of complex structure of materials.