Axis 5 : Coupling and control

The axis « Coupling & Control » aims at investigating several kinds of interaction mechanisms between ultrasound and living tissues or cells. Amongst the possible interactions acting in therapeutical applications such as ultrasound-mediated bone stimulation, drug delivery process through cell sonoporation or sonothrombolysis, we particularly focus on: (i) the direct mechanical stimulus induced by the acoustic wave and (ii) the indirect stimulus induced by cavitation bubbles or acoustic streaming. The research activities then deal with fundamental understanding (numerical, theoretical or experimental) of these interactions, combined to the design of new ultrasound approaches. 

The research works are divided into three main thematics:

  1. Ultrasound cavitation control and bubble dynamics:

Variou aspects of the dynamics of ultrasound cavitation (initiation, maintenance, levelling) are investigated in the aim of controlling cavitation phenomenon. This control is performed (i) spatially by trapping bubbles on deterministic trajectories or to (anti-) nodes of the acoustic field and (ii) temporally by real-time monitoring and control of the cavitation activity at the spatial scale of the bubble cloud, either in-vitro or in-vivo. At mid-term this should allow the total discrimination of the cavitation regimes experienced by bubbles, namely the stable or inertial regime, in order to fully differentiate their respective influence on biological effects.

Proposed approaches: numerical investigations of single and collective bubble dynamics, high-speed visualization of bubble dynamics, passive acoustic monitoring and real-time control programming.

On-going collaborations: Hao-Li Liu (Chang-Gung University, Taoyuan, Taiwan), Serge Dos Santos (Inserm U930 Tours), Sebastien Tanguy (IMFT, Toulouse)

  1. Ultrasound streaming and microstreaming

In therapeutic applications such as sonoporation or sonothrombolysis, the coupling between acoustic wave and the surrounding fluid plays a key role in the action induced by ultrasound to surrounding tissues or cells. This coupling is induced either the acoustic wave itself (through large scale acoustic streaming) or by microbubbles oscillations (through small-scale microstreaming). In this framework this research thematics aims at characterizing the fluid flow patterns and the induced particle mixing in ultrasound focused beams and/or confined geometries.

Proposed approaches: particle tracking in complex fluids, PIV technique, holography

On-going collaborations: Valery Botton (LMFA, Ecully), Cyril Mauger & Philippe Blanc-Benon (LMFA, Ecully), Maher Ben Chiekh (LESTE, Monastir, Tunisie)

  1. Tissue and cell responses to ultrasound sollicitations

In order to fully understand the disparity between cell lines in terms of response to given and controlled ultrasound stimuli, we perform biological and biophysical studies by varying the ultrasound characteristics, cell lines (adherent, suspended, primary ones) to investigate cell proliferation, motility and modification of gene expression. Particularly new technological devices allowing the controlled studies of bubble-cell interactions are designed in order to elucidate the drug internalization mechanisms (membrane poration, endocytosis) underlying cell sonoporation.

Proposed approaches: confocal microscopy, microelastography techniques, RNA-chip microarray

On-going collaborations: Wen-Shiang Chen (NTUH, Taipei, Taiwan), Jean-Paul Rieu (ILM, Lyon), Benjamin Gibert (CRCL, Lyon)