The nonlinear response of ultrasound contrast agent microbubbles is investigated through various simulations in regimes of clinical relevance. A spherical model is used based on a compressible form of the Rayleigh-Plesset equation that is combined with a thin-shell model developed by Lars Hoff to simulate the radial response of contrast agents subject to ultrasound. The response of a Sonazoid contrast agent is analyzed through the application of techniques from dynamical systems theory such as phase portraits, Poincaré sections, bifurcation diagrams, and Lyapunov exponents to illustrate the qualitative dynamics and transition to chaos that occurs under certain changes in system parameters. The dynamic response of the contrast agent is shown to be similar regardless of the filling gas assumed or the presence of blood or water as the external medium. The effect of continuous and pulsed acoustic forcing is also compared. Furthermore, an experimental setup for investigating the dynamic response of contrast agents subject to ultrasound is presented that uses a standing acoustic wave to trap and drive bubbles at a prescribed frequency. The feasibility of the apparatus is demonstrated through high-speed images of an air bubble trapped at the antinode of the acoustic chamber.

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