A model for acoustic vaporization of droplets encapsulated within a nonlinear hyperelastic shell

Abstract

Nanometric particles with a liquid core arise an increasing interest for medical applications such as contrast imaging and targeted drugs delivery. Unlike conventional ultrasonic contrast agents with a gaseous core (ACU), their dimensions are smaller than the gap endothelium of tumor blood vessels, allowing them to reach tumor tissues. However, because of this liquid core, these particles are poorly compressible and therefore less efficient for imaging than standard ACUs. Their echogenicity may be enhanced by vaporizing the liquid core when applying an ultrasonic field. The investigated particles are made of a liquid core encapsulated within a visco-elastic shell. One assumes the existence of a vapor nucleus at initial time. The shell confines the liquid core and ensures greater stability, but it usually inhibits the spontaneous growth of vapor core. The dynamic of the liquid-vapor interface is described by a generalized Rayleigh-Plesset equation coupled with the heat diffusion equation in the dense phase...