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(a) Schematic representation of acoustic and optical alignment achieved with needle hydrophone. Transducer focal length, , is 2 in and typical tube depth is approximately Expanded area shows phantom and microbubble location. —inner diameter, —outer diameter, distance of microbubble from tube end, and —microbubble diameter.
(a) , , , PMMA tube, ; (b) , , , PMMA tube, ; (c), , , PMMA tube, ; (d), , , PMMA tube, . Oscillation amplitude in (d) is greater than (b) and (c), but less than (a). Scale bar indicates spatial dimension along vertical axis, vertical lines indicate increments.
Normalized expansion of a microbubble based on experimental observations and Rayleigh-Plesset predictions. (a) Bubble expansion in tube with and at multiple transmission pressures and in cellulose tube with and insonation at 1.4 MPa. (b) Expansion and fragmentation with a 1 MHz, 5 cycle pulse PMMA tube with , comparing and . (c) Expansion ratios for microbubbles driven with a 1 MHz, 5 cycle pulse for three tube diameters: , , and (cellulose). (d) Rayleigh-Plesset predictions for microbubble expansion in an infinite fluid at three transmission pressures and experimental observations for the expansion in the first two cycles in cellulose tubing with .
Streak image demonstrating displacement due to radiation force produced by a 5 MHz, 20 cycle pulse with a in a tube with and . A microbubble with initial diameter of approximately is displaced by this pulse, and the microbubble is intact after insonation.
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