| Popis: |
Laser induced optical breakdown (LIOB) in fluids produces a localized plasma, an expanding radial shock wave front, heat transfer from the plasma to the fluid, and the formation of cavitation bubbles. Collectively these phenomena are referred to as photodisruption. Subjecting photodisruptively produced cavitation bubble nuclei to an ultrasonic field can result in strong cavitation and local cellular destruction. The ability of ultrafast lasers to produce spatially localized photodisruptions with microJoule pulse energies in combination with the possibility of larger scale tissue destruction using ultrasound presents an attractive and novel technique for selective and non-invasive tissue modification, referred to as photodisruptively nucleated ultrasonic cavitation (PNUC). Optimization of PNUC parameters in a confocal laser and ultrasound geometry is presented. The cavitation signal as measured with an ultrasound receiver was maximized to determine optimal laser and ultrasound spatial overlap in water. A flow chamber was used to evaluate the effect of the laser and ultrasound parameters on the lysis of whole canine red blood cells in saline. Parameters evaluated included laser pulse energy and ultrasound pressure amplitude. |
