Acoustic levitation of liquid drops: Dynamics, manipulation and phase transitions

The technique of acoustic levitation normally produces a standing wave and the potential well of the sound field can be used to trap small objects. Since no solid surface is involved it has been widely applied for the study of fluid physics, nucleation, bio/chemical processes, and various forms of soft matter. In this article, we survey the works on drop dynamics in acoustic levitation, focus on how the dynamic behavior is related to the rheological properties and discuss the possibility to develop a novel rheometer based on this technique. We review the methods and applications of acoustic levitation for the manipulation of both liquid and solid samples and emphasize the important progress made in the study of phase transitions and bio-chemical analysis. We also highlight the possible open areas for future research. Acoustically levitated liquid drop is readily to serve as a micro-reactor which may bring about unusual effects to the chemical/physical processes inside it. [Display omitted] •Acoustic levitation has been widely applied in drop dynamics and manipulation.•The dynamic behavior of the acoustically levitated drop is related to its rheological properties.•Acoustic levitation causes unusual physical/chemical effects in the levitated drops due to the avoidance of solid walls.