Holographic acoustic assembly and manipulation
Acoustic waves exert forces when they interact with matter. Sound, and in particular ultrasound, which has a wavelength of a few hundred microns in water, is a benign and versatile tool, that has been successfully used to manipulate, trap and levitate microparticles and cells. The acoustic contrast between the material and the medium, and the spatial variation of the ultrasound field determine the interaction. Resonators and arrays of a few hundred transducers have thus far been used to generate the sound fields, but the former only yields highly symmetrical pressure patterns, and the latter cannot be scaled to achieve complex fields. 

Our radically new approach uses a finely contoured 3D printed acoustic hologram to generate pressure fields with orders of magnitude higher complexity than what has been possible to date. The acoustic hologram technology is a route towards truly sophisticated and 3D sound fields. This project will research the necessary computational and experimental tools to generate designed 3D ultrasound fields. We will investigate ways to use acoustic holograms for rapid manufacturing, the controlled manipulation of microrobots, and the assembly of cells. The 3D pressure fields promise the assembly and fabrication of an entire 3D object in “one shot”, something that has not been realized to date. We will also study the formation of 3D cellular assemblies, and more realistic 3D tumour models. This project will develop the technology, materials, processes, and understanding needed for the generation and use of sophisticated 3D ultrasound fields, which opens up entirely new possibilities in physical acoustics and the manipulation of matter with sound.