Nucleating cavitation from laser-illuminated nano-particles

Fundamentals of Cavitation

“…The expansion of the heated volume further results in the formation of a cavity, if it occurs in a solid, or of a cavitation bubble, if it takes place in a liquid (Vogel et al 1996). The process, called photoacoustic cavitation (Farny et al 2005), can also be classified as energetic cavitation.…”

“…Bubble formation begins when the superheated liquid surrounding the nanoparticle approaches the spinodal temperature of water (*550 K), and additional optical energy is required for subsequent bubble growth (Kotaidis et al 2006). The cavitation threshold fluence can be reduced by reducing the local pressure at the nanoparticle position during the time of illumination using an applied ultrasound field; a process referred to as photoacoustic cavitation (Farny et al 2005). When nanoparticles are subjected to negative pressure, such as is encountered during the rarefaction phase of the applied ultrasound field, they have a drastically reduced cavitation threshold fluence.…”

Dynamics of tandem bubble interaction in a microfluidic channel

“…Patterning of micron-sized gold dots on a glass surface It has been shown previously that vapor microbubbles can be generated via laser-induced localized heating of metal surfaces immersed in water (Yang, 2007) or nanoparticle dispersed tissue mimicking materials (Farny et al, 2005). To produce tandem bubbles with precision in nucleation sites and desirable spatial distribution, a glass surface was treated by coating it with an array of paired gold dots having a separation distance of 40 lm using metal lift-off technique (Schoning et al, 2005).…”

Physical Principles of Microbubbles for Ultrasound Imaging and Therapy

“…It is, however, frequently observed in HIFU surgery and, as will be described below, the bubbles formed can produce violent effects which can aid ablation of the target volume but which can also cause unwanted damage to the surrounding healthy tissue. It is for this reason that contrast agent microbubbles and also hydrophobic nanoparticles [19, 56] have been investigated as means of seeding cavitation at lower ultrasound intensities rather than relying on the formation of bubbles at naturally occurring nucleation sites in vivo, the nature of which is not fully understood.…”