Tuning Initial Surface Tension and Buckling Pressure of Monodisperse Microbubbles by Changing Agitation Time

Monodisperse microbubbles (MDMBs) exhibit great potential for applications in ultrasound imaging and therapy. Previous studies have established that the initial surface tension and buckling pressure of microbubbles have significant influence on the acoustic behavior. By regulating the diffusive Ostwald ripening process, the lipid density on the MDMB shell can be changed, thereby tuning the initial surface tension and buckling pressure. This study aims to investigate whether varying the agitation time in air-saturated saline solution can effectively tune the initial surface tension and buckling pressure of MDMBs. Our results demonstrated that MDMBs agitated for 13 min exhibited significantly lower initial elasticity compared to those agitated for 20 s or 3 min. The initial surface tension decreased progressively with increasing agitation time. Both the buckling pressure and rupture pressure decreased as agitation time increased. These results indicate that the MDMBs gradually transition towards the buckling state under prolonged agitation. MDMBs agitated for 13 min with lower initial surface tension show enhanced suitability for subharmonic signal generation, while MDMBs agitated for 20 s with higher buckling pressure exhibit improved resistance to high-pressure environments within blood vessels.