Microscale actuation using acoustofluidics for rapid micromanipulation and 3D printing

Whereas acoustic fields are widely used for nondestructive evaluation and testing, these same fields can be utilized for actuation with appropriate setups and acoustic amplitudes. Here time-averaged acoustic radiation pressures and forces can be leveraged for micromanipulation, with these arising from diffractive acoustic fields, standing pressure fields, travelling waves, acoustic streaming and related nonlinear acoustic phenomenon. Acoustic fields are particularly useful for activities related to patterning, sorting and mixing of microspecimens, where the wavelength of typical > MHz order acoustic fields approaches that of individual cells, affording rapid manipulation activities. Whereas the much of the acoustofluidic literature has examined the use of acoustic standing waves to accomplish fairly simple lines and grids of particles, here we explore the use of novel acoustofluidic effects and method including microresonators, metamaterials and acoustic holography to generate more complex and tailored outcomes. Further we examine our recent work in 3D printing and the potential for future efforts to combine these developments with acoustic micromanipulation.