Dr Valeria Garbin
Chemical Engineering
Imperial College London
London SW7 2AZ
+44 20 759 42878
v.garbin at

Postdoc position

We are looking for a postdoc in Soft Matter and Rheology (experiment) as part of the ERC-funded project ExtreFlow. For details and to apply online, follow this link. Closing date: 30 September 2017.




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Microbubble dynamics

oscillating bubbleOne very fascinating application of bubbles is in biomedical imaging. Microbubbles about 1-2 μm in size are a safe and effective contrast agent for ultrasonography. These biomedical microbubbles are composed of a low-solubility gas core stabilized by a surfactant layer. In an ultrasound wave, the microbubble volume oscillates at MHz frequency, thus producing a secondary ultrasound wave. The ultrasound wave emitted by an oscillating microbubbles has a distinctive acoustic signature, which is at the basis of the contrast enhancement mechanism. 

Fundamental questions in fluid mechanics and acoustics arise when investigating the dynamics of biomedical microbubbles in ultrasound. We addressed several outstanding questions by performing precise measurements on single microbubbles using optical tweezers and a custom ultra-high speed camera, the Brandaris 128 (Rev. Sci. Instrum., 2003). With Physics of Fluids Group at the University of Twente.

We directly measured hydrodynamic forces acting on single microbubbles and established the role of unsteady viscous forces on the translation of coated bubbles. We provided an explanation for the strongly nonlinear acoustic response of coated bubbles based on microscopic mechanisms in the surfactant coating: our high-speed recordings revealed buckling of the phospholipid coating at MHz frequency.

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T. Kokhuis, V. Garbin, K. Kooiman, B. Naaijkens, L. Juffermans, O. Kamp, T. van der Steen, M. Versluis, and N. de Jong, Secondary Bjerknes forces deform targeted microbubblesUltrasound in Medicine and Biology 39, 490-506 (2012)

V. Garbin, M. Overvelde, B. Dollet, N. de Jong, D. Lohse, and M. Versluis, Unbinding of targeted ultrasound contrast agent microbubbles by secondary acoustic forces, Physics in Medicine and Biology 56, 6161-6177 (2011)

M. Overvelde, V. Garbin, B. Dollet, N. de Jong, D. Lohse, and M. Versluis, Dynamics of coated microbubbles adherent to a wall, Ultrasound in Medicine and Biology 37, 1500- 1508 (2011)

J. Sijl, M. Overvelde, B. Dollet, V. Garbin, N. de Jong, D. Lohse, and M. Versluis, “Compression-only” behavior: A second order nonlinear response of ultrasound contrast agent microbubbles, Journal of the Acoustical Society of America 129, 1729-1739 (2011)

M. Overvelde, V. Garbin, B. Dollet, J. Sijl, N. de Jong, D. Lohse, and M. Versluis, Nonlinear shell behavior of phospholipid-coated microbubbles, Ultrasound in Medicine and Biology 36, 2080-2092 (2010)

J. Sijl, B. Dollet, M. Overvelde, V. Garbin, T. Rozendal, N. de Jong, D. Lohse, and M. Versluis, Subharmonic behavior of phospholipid-coated ultrasound contrast agent microbubbles, Journal of the Acoustical Society of America 128, 3239-3252 (2010)

V. Garbin, B. Dollet, M. Overvelde, D. Cojoc, E. Di Fabrizio, L. van Wijngaarden, A. Prosperetti, N. de Jong, D. Lohse, M. Versluis, History force on coated microbubbles propelled by ultrasound, Physics of Fluids 21, 092003 (2009)

B. Dollet, S.M. van der Meer, V. Garbin, N. de Jong, D. Lohse, M. Versluis Nonspherical oscillations of ultrasound contrast agent microbubbles, Ultrasound in Medicine and Biology 34, 1465-1473 (2008)

V. Garbin, D. Cojoc, E. Ferrari, E. Di Fabrizio, M. L. J. Overvelde, S. M. van der Meer, N. de Jong, D. Lohse and M. Versluis, Changes in microbubble dynamics near a boundary revealed by combined optical micromanipulation and high-speed imaging, Applied Physics Letters 90, 114103 (2007)