Partner: S. Hilgenfeldt


Recent publications
1.Postema M., Marmottant P., Lancée Ch.T., Hilgenfeldt S., de Jong N., Ultrasound-induced microbubble coalescence, ULTRASOUND IN MEDICINE AND BIOLOGY, ISSN: 0301-5629, DOI: 10.1016/j.ultrasmedbio.2004.08.008, Vol.30, No.10, pp.1337-1344, 2004
Abstract:

We studied the interaction of ultrasound contrast agent bubbles coated with a layer of lipids, driven by 0.5 MHz ultrasound. High-speed photography on the submicrosecond timescale reveals that some bubbles bounce off each other, while others show very fast coalescence during bubble expansion. This fast coalescence cannot be explained by dissipation-limited film drainage rates. We conclude that the lipid shell ruptures upon expansion, exposing clean free bubble interfaces that support plug flow profiles in the film and inertia-limited drainage whose time scales match those of the observed coalescence.

Keywords:

Microbubble coalescence, Ultrasound contrast agent, Film drainage, High-speed photography

Affiliations:
Postema M.-other affiliation
Marmottant P.-other affiliation
Lancée Ch.T.-other affiliation
Hilgenfeldt S.-other affiliation
de Jong N.-other affiliation

Conference papers
1.Postema M., Marmottant P., Lancée C.T., Versluis M., Hilgenfeldt S., de Jong N., Ultrasound-induced coalescence of free gas microbubbles, IUS 2004, IEEE International Ultrasonics Symposium, 2004-08-23/08-27, Montreal (CA), DOI: 10.1109/ULTSYM.2004.1417653, Vol.1, pp.1-4, 2004
Abstract:

When gas bubbles collide, the following stages of bubble coalescence have been reported: flattening of the opposing bubble surfaces prior to contact, drainage of the interposed liquid film toward a critical minimal thickness, rupture of the liquid film, and formation of a single bubble. During insonification, expanding contrast agent microbubbles may collide with each other, resulting in coalescence or bounce.
In this study, we investigate the validity of the film drainage formalism for expanding free bubbles, by subjecting rigid-shelled contrast agent microbubbles to ultrasound, in order to release gas, and photograph the coalescence of these free gas bubbles. As with colliding bubbles, bubble surface flattening is related to the Weber number. Only inertial film drainage between free interfaces explains the observed coalescence times. In accordance with theory, smaller bubble fragments coalesce on very small time scales, while larger bubbles bounce off each other.

Affiliations:
Postema M.-other affiliation
Marmottant P.-other affiliation
Lancée C.T.-other affiliation
Versluis M.-other affiliation
Hilgenfeldt S.-other affiliation
de Jong N.-other affiliation

Conference abstracts
1.Postema M., Marmottant P., Lancée C., Hilgenfeldt S., de Jong N., Ultrasound-induced microbubble coalescence by parametric instability, 10th Dutch Annual Conference on BioMedical Engineering, pp.177, 2003