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Stress waves traveling in a nonlinear acoustic lens and sound bullet formation in the adjacent fluid medium (numerical results). In the lens, the sphere colors are proportional to the contact-force amplitude. Waves emitted by the nonlinear acoustic lens reach the host medium (via an elastic interface), where they generate compact spherical pressure waves. The pressure waves coalesce in the host medium and form a sound bullet. The color bar on the right represents the scale of pressure intensity (Pa) in the host medium.
The system is still under development and has not yet been tested on living cells. It is likely to be some years before it is available for medical or other applications.