Real-time monitoring and control of stable cavitation activity in pulsed sonication

Abstract

Even if bubbles collapses are commonly thought to be the key element of cell permeabilization for drug delivery applications, recent works have demonstrated the possibility of transfecting cells by gentle oscillating bubbles (stable cavitation), possibly resulting in lower cell lysis or tissue damages. Nevertheless, in a bubble cloud, both stable and inertial cavitation activities would naturally coexist, thus making difficult to quantify the contribution of both regime on the drug delivery process. To distinguish each cavitation regime, a feedback-loop process is implemented on the subharmonic component emitted from the bubble cloud generated in a water tank by a focused transducer. This feedback loop, acting at a 250µs loop rate, allows adjusting the level of subharmonic emission as well as measuring inertial cavitation activity (broadband noise emission), by real-time modulating the applied voltage to the transducer. Evidences of control of the stable cavitation activity are reported, associated with (...