Microbubble Collapse upon Focused Ultrasound Exposure in Narrow Tubes

Abstract

Microbubbles are currently used as ultrasound contrast agents. Their potential therapeutic applications are also under investigation. Some aspects of microbubble behavior upon ultrasound exposure in narrow tubes are discussed. It is shown experimentally that the threshold for bubble collapse, as recorded by broadband acoustic emission, is not only dependent on the applied pressure amplitude, but also on the tube size with an increase for smaller vessels. This result is interpreted in term of a simple mathematical model, based on the change of the resonance frequency and damping of a microbubble in small vessels.