Current involved researchers (LabTAU): Corentin Cornu (PhD student), Matthieu Guedra (Postdoc), Claude Inserra (Ass. Prof.), Bruno Gilles (Ass. Prof.), Jean-Christophe Bera (Prof.)
Current involved collaborative researchers: Cyril Mauger (Ass. Prof., LMFA, Lyon), Christelle Der Loughian (Ass. Prof., MATEIS, Lyon), Jean-Paul Rieu (Prof., ILM, Lyon)
Past involved researchers: Pauline Labelle (Postdoc LMA, Marseille), Cyril Desjouy (Postdoc LMFA, Lyon)
Bubble dynamics in strong acoustic field
Depending on forces it experiences, bubbles in a liquid exhibit different kind of motions, including zigzag or spiraling motions, induced by the acoustic radiation force on a single bubble, called the primary Bjerknes force. When bubbles smaller than the resonant radius are located in a standing acoustic wave, they are pushed towards the acoustic pressure antinode and form a bubble cluster. For bubbles larger than the resonant size, they naturally move towards the pressure node, that can be a ring in a cylindrical geometry (see Figure). This simple view in linear acoustic does not take into account the possible coupling between bubble translation and their radial oscillation, coupling that appears in sufficiently strong acoustic field. In this case, bubbles smaller than the resonant size can concentrate around the pressure node that corresponds to the stable equilibrium location for large bubbles. The existency and combination of the two radial and longitudinal modes propagating in the resonator allows the possibility for small bubbles to coexist with larger bubbles in the vicinity of the their linearly unstable equilibrium location through orbital or spiraling motions.
 Orbital trajectory of an acoustic bubble in a cylindrical resonator. Desjouy C, Labelle P, Gilles B, Bera JC, Inserra C. Phys. Rev. E, 88, 033006, 2013.
 Acoustic bubble behavior in a standing wave field. Desjouy C, Labelle P, Billes B, Bera JC, Inserra C. J. Acoust. Soc. Am., 133 (5):3277, 2013.
Bubble behavior in the vicinity of cell-mimicking membranes
In the context of sonoporation, we use supported lipid bilayers as a model for biological membranes and investigate the interactions between the bilayer and microbubbles induced by ultrasound. When applying ultrasound and generating microbubbles above a supported biomimetic membrane, a bubble cloud appears both in transmission and fluorescent images (see Figure below), indicating that bubbles collect fluorescent lipids from the bilayer. By recording the vicinity of the bubble cloud with an epifluorescence microscope equiped with a fast sensitive camera, we could observe the very fascinating behavior of jumping bubbles on the bilayer, forming a necklace pattern of alteration on the membrane. By watching more carefully these bubble dynamics, we found that these cavitating bubbles are regularly pumping lipids from the bilayer, allowing the entrance of water below the bubble, reducing its adhesion, and finally jumping to a nearby position with a noticeable regularity. Qualitatively these instabilities result from a competition between downward oriented van der Waals and Bjerknes forces on one hand and upward oriented hydrodynamic lift forces on the other hand.
 Jumping acoustic bubbles on lipid bilayers. Der Loughian C, Muleki Seya P, Pirat P, Inserra C, Bera JC, Rieu JP. Soft Matter, 11:3460-3469, 2015.
 Monitoring and control of inertial cavitation activity for enhancing ultrasound transfection: the SonInCaRe project. C. Inserra, P. Labelle, C. Der Loughian, J.L. Lee, M. Fouqueray, J. Ngo, A. Poizat, C. Desjouy, B. Munteanu, C.W. Lo, C. Vanbelle, J.P. Rieu, W.S. Chen, J.C. Bera. IRBM, 35(2): 94-99, 2014.