Effect of low intensity CW ultrasound on acoustic responses of microbubblesgenerated from phase change nano droplet

Kenichi Kawabata, Rei Asami, Takashi Azuma, Shinichiro Umemura

Research output: Chapter in Book/Report/Conference proceedingConference contribution

1 Citation (Scopus)

Abstract

Sustaining of microbubbles generated from a phase-change nano-droplet(PCND) was demonstrated by using low intensity ultrasound aiming at preciselytargeted ultrasound therapy. PCND, a droplet containing superheatedperfluorocarbon, dispersed in polyacrylamide gel was exposed to 1.1-MHzultrasound pulses at 1.2 kW/cm2 with 100 cycles. The resultingmicrobubbles were further exposed to very low intensity continuous wave (CW) orburst ultrasound to sustain the bubbles. When CW exposure was used for thesustaining procedure, only fundamental components were observed from the PCND atacoustic intensities around 100 mW/cm2. This suggests thefundamental signal was emitted from the sustained microbubbles because furtherexposure of 100 W/cm2 ultrasound following the sustaining ultrasoundresulted in the generation of fractional harmonics, suggesting the induction ofcavitation, while no harmonic components were observed in the absence of thesustaining ultrasound. It was possible to use pulsed ultrasound for thesustaining procedure, when the interval between each pulse was within 10 ms. Thetime constant was about the same as the lifetime of the microbubbles inducedfrom the PCND in the absence of the sustaining ultrasound. The obtained resultsare promising for controlling the sensitivity of local sites to therapeuticultrasound by using PCND and low intensity ultrasound

Original languageEnglish
Title of host publication2010 IEEE International Ultrasonics Symposium, IUS 2010
Pages1940-1943
Number of pages4
DOIs
Publication statusPublished - 2010 Dec 1
Event2010 IEEE International Ultrasonics Symposium, IUS 2010 - San Diego, CA, United States
Duration: 2010 Oct 112010 Oct 14

Publication series

NameProceedings - IEEE Ultrasonics Symposium
ISSN (Print)1051-0117

Other

Other2010 IEEE International Ultrasonics Symposium, IUS 2010
CountryUnited States
CitySan Diego, CA
Period10/10/1110/10/14

Keywords

  • cavitaion
  • microbubble
  • nano droplet
  • phase-change

ASJC Scopus subject areas

  • Acoustics and Ultrasonics

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    Kawabata, K., Asami, R., Azuma, T., & Umemura, S. (2010). Effect of low intensity CW ultrasound on acoustic responses of microbubblesgenerated from phase change nano droplet. In 2010 IEEE International Ultrasonics Symposium, IUS 2010 (pp. 1940-1943). [5935683] (Proceedings - IEEE Ultrasonics Symposium). https://doi.org/10.1109/ULTSYM.2010.5935683