Observation of acoustic streaming near Albunex® spheres

Using Albunex® spheres (a contrast agent for ultrasonic imaging), a specially designed microscopic device, a video peak storage technique and micron-size Latex spheres as tracers, acoustic streaming patterns around a single and a pair of Albunex® spheres of a few tens micrometer radius in a 160-kHz ultrasonic standing wave field have been recorded. The spatial peak pressure amplitude of the standing wave was estimated to be of the order of 0.5 MPa with optical interferometry. The acoustic streaming velocity was in the range of 50–100 μm/s.