Micro bubble aggregation by interference of incident and the secondary ultrasonic waves and its application to bubble characterization

When the micro bubbles flow into the ultrasonic wave field, it is often observed that the bubbles make aggregation and the aggregated bubble pattern changes depending on the ultrasonic wave frequency and the bubble itself. In this paper, the micro bubble aggregation under an interference wave field which is produced by an incident ultrasonic wave and the secondary ultrasonic waves radiated from the oscillating bubbles is discussed. It is derived that the relative phase between the secondary wave radiation and the radial oscillation of the surrounding bubble, the secondary ultrasonic wave frequency are the parameters in order to characterize the bubble aggregation. The experiments are carried out for an ultrasonic wave contrast agent and the bubble with PVC shell. Characterization of bubble oscillation by aggregated bubble pattern analysis is proposed.