Figure 1.

Amplification of bubble nonlinear response due to the presence of nanoparticles on the bubble surface. (a) Simulation of the radial oscillations of a bubble (normalized with respect to the initial diameter R₀=75 μm) excited by an ultrasound pulse with centre frequency 1 MHz and peak negative pressure 25 kPa. The grey and black curves (overlapping during the first two cycles) show the response of a bubble with and without nanoparticles, respectively. (b) Frequency spectrum for the scattered ultrasound field produced as a result of the oscillations shown in (a). The backscattered power is plotted normalized with respect to the maximum.