Experimental study to improve local trapping efficiency of microbubbles by time-shared emission of three-dimensional acoustic field

Toi Sawaguchi, Naoto Hosaka, Ren Koda, Shinya Onogi, Takashi Mochizuki, Kohji Masuda

Research output: Contribution to journalArticle


We previously reported our attempts to increase local concentration of microbubbles in water flow by acoustic radiation force, with the aim to apply to ultrasound therapy. Because the actual blood vessels are generally structurally complex and contain multiple bifurcations, trapping microbubbles in multiple areas will improve total therapeutic efficiency. However, there is a limitation to the number of ultrasound transducers that can be placed on the body surface, since a single-element transducer produces only one focal point. In this study, we developed a method to trap microbubbles (bubble liposome) that may contain various kinds of drugs in multiple areas by designing a time-shared acoustic field produced by a 2D array transducer at a frequency of 1 MHz. First, we conducted an experiment to trap microbubbles in a straight path of an artificial blood vessel to investigate the relationship between the trapped area and ultrasound parameters. Next, we conducted an experiment to produce a time-shared acoustic field under optimal conditions : maximum sound pressure of 150 kPa-pp and duty ratio of 25% in ultrasound emission. Under these conditions, we succeeded in trapping microbubbles simultaneously in four individual parallel paths with inner diameter of 0. 7 mm, in a multibifurcated artificial blood vessel model. We also measured the area of trapped microbubbles under a continuous wide acoustic field that covered the area of four paths. Using the same ultrasound power, the time-shared acoustic field had improved trapping efficiency compared to the continuous acoustic field.

Original languageEnglish
Pages (from-to)179-186
Number of pages8
JournalTransactions of Japanese Society for Medical and Biological Engineering
Issue number3
Publication statusPublished - 2015 Oct 29


  • 2D array transducer
  • Bubble liposome
  • Time-shared emission
  • Trapping efficiency

ASJC Scopus subject areas

  • Biomedical Engineering

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