THE EFFECT OF ULTRASONICATION MODE ON THE DYNAMICS OF MICROBUBBLE OSCILLATION AND SAFE VESSEL WALL DISPLACEMENT

The purpose of this study is to investigate the effect of the sonication modes of single-frequency waves on the change of the microbubble radius and the displacement of the microvessel wall. By comparing the results with the results obtained from the modeling of the data, the safety of which was proven, the sonication duty factors that safely create displacement in the vessel wall in the presence of microbubbles were extracted. Therefore, continuous mode (duty factor 100%) and pulsed modes (duty factors 25%, 50% and 80%) were modeled in the fluid-microbubble–vessel system. The two-dimensional finite element method is used. The blood as fluid in the microvessel is considered a homogeneous, incompressible and single-phase Newtonian fluid. The binding boundary conditions at the boundaries are the continuity laws of velocity and pressure. The laws of conservation of mass and momentum must also be considered. A microbubble (radius [Formula: see text]m) is considered in a blood microvessel with a radius of [Formula: see text]m, which was exposed to ultrasound at a frequency of 1[Formula: see text]MHz with a pressure amplitude of 0.25[Formula: see text]MPa. The model was validated by a valid numerical study. The results showed that as the duty factor of ultrasound waves increases, the duration in which the microbubble oscillates increases, but the [Formula: see text] is the same for all (22% increase compared to the [Formula: see text]). Also, the time average of microvessel wall displacement (TAD) increases) at 1.31, 1.78, 1.98 and 2.31[Formula: see text]nm, respectively, for duty factors 25%, 50%, 80% and 100% at point A, the closest point to the microbubble). It is concluded that for this sonication protocol, the duty factors of 50%, 80% and 100% are in the interval of creating permeability safely, and the duty factor of 25% is smaller than this range.