Non-contact droplet manipulation and its dynamics based on acoustic levitation

Abstract

Acoustic levitation is a unique technique which can accomplish levitation of small objects via acoustic radiation force caused by the nonlinear effect of ultrasound. Because of the avoidance of solid surface, the technique is extremely suitable for the container-free manipulation of liquid samples, therefore it could be widely used in droplet dynamic study and droplet-based microreactions and analysis. In this paper, we introduce briefly the principles and technical details of acoustic levitation, and review the state of the art of acoustically levitated droplet dynamics including its equilibrium shape, oscillation, instability and associate flows. We also discuss the droplet manipulation approaches via acoustic levitation. Finally, we propose several potential directions for future research in this area.