To examine the effects of microbubble behaviors on the soft material like a living tissue, the collapse behaviors of the bubble on the agar were observed optically under ultrasound irradiation. It was clearly observed that micro-jet formed the micro porus. Also, it is shown that agar surface pulsates locally due to the violent bubble vibration. Moreover, these results suggest that the violent bubble vibration injects the liquid around the bubble into the porus formed by micro-jet. This report will largely contribute the development of the therapy technique with microbubbles because there are few reports about the observation of the detail collapsing behaviors on the soft material.

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