Ultrasound mediated drug delivery: the effect of microbubbles on a gel boundary.

When microbubble contrast agents are driven by ultrasound, the transport of drugs and particles across cell membranes and blood vessel walls is enhanced. While a wide range of acoustic parameters enhance delivery, the acoustic parameters that maximize delivery while simultaneously minimizing biological effects have not been fully characterized. Here, we use a gel phantom with a Young's modulus similar to that of tissue to directly observe bubble interaction with the gel surface during insonation. Using parameters relevant to diagnostic imaging and drug delivery, we observe fluid jets that impinge on the surface and tunnels that follow the sound beam axis.