Abstract
Laser-induced breakdown of an optically trapped nanoparticle is a unique system for studying cavitation dynamics. It offers additional degrees of freedom, namely the nanoparticle material, its size, and the relative position between the laser focus and the center of the optically trapped nanoparticle. We quantify the spatial and temporal dynamics of the cavitation and secondary bubbles created in this system and use hydrodynamic modeling to quantify the observed dynamic shear stress of the expanding bubble. In the final stage of bubble collapse, we visualize the formation of multiple submicrometer secondary bubbles around the toroidal bubble on the substrate. We show that the pattern of the secondary bubbles typically has its circular symmetry broken along an axis whose unique angle rotates over time. This is a result of vorticity along the jet towards the boundary upon bubble collapse near solid boundaries.
Highlights
Cavitation dynamics have been at the heart of a range of key physical developments in the last century
It is worth mentioning that due to the smaller bubble sizes, the maximum wall shear stress produced by the laser-induced breakdown (LIB) of a nanoparticle at equivalent radial locations is typically two orders of magnitude lower than those in previous studies where the LIB was performed in aqueous media alone [14]
The spatial and temporal dynamics of the cavitation and secondary bubbles resulting from the LIB of an optically trapped single nanoparticle were quantified using nanosecond time-resolved imaging
Summary
Cavitation dynamics have been at the heart of a range of key physical developments in the last century. The recent use of optical breakdown of a trapped nanoparticle within a liquid environment [8] opens up new vistas in this field by providing a powerful test system for exploring hitherto unanswered physical questions regarding cavitation dynamics, bubble formation, and evolution. Such dynamical processes are central to a range of key techniques, in the biomedical sciences including targeted cell lysis and dissection or inactivation of material such as cellular organelles, cytoskeletal filaments, and chromosomes [9–11]. Our results confirm that LIB of nanoparticles with nanosecond laser sources offers unprecedented confinement of cavitation bubbles compared to that from nanosecond LIB of a liquid alone [8]
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