Investigation of cavitation bubble dynamics using particle image velocimetry: implications for photoacoustic drug delivery

Photoacoustic drug delivery is a technique for delivering drugs to localized areas in the body. In cardiovascular applications, it uses a laser pulse to generate a cavitation bubble in a blood vessel due to the absorption of laser energy by targets (e.g., blood clots) or surrounding liquids (e.g., blood or injected saline). The hydrodynamic pressure arising from the expansion and collapse of the cavitation bubble can force the drug into the clots and tissue wall tissue. Time-resolved particle image velocimetry was used to investigate the flow of liquids during the expansion and collapse of cavitation bubbles near a soft boundary. A gelatin-based thrombus model was used to simulate the blood clot present during laser thrombolysis. An argon laser chopped by an acousto-optic modulator was used for illumination and photography was achieved using a CCD camera. The implications of this phenomenon on practical photoacoustic drug delivery implementation are discussed.