Influence of nonlinear effects on the acoustic levitation of small spheres

This paper presents the nonlinear characterization of a single-axis acoustic levitator and the analysis of the influence of nonlinear effects on the acoustic levitation of small spheres. First, the nonlinear characterization of the levitator is performed by applying an electronic balance to measure the acoustic radiation force that acts on the reflector as a function of the separation distance between the transducer and the reflector. Then, small spheres of different materials are acoustically levitated and a high-speed camera is used to obtain the sphere position as a function of time for different separation distances. The measurement of the acoustic radiation force on the reflector shows that the force becomes asymmetric, leading to a jump phenomenon on force-distance curve. Measurements with the high-speed camera show that, depending on the density of the levitated sphere, it can falls over the reflector when the jump phenomenon occurs.