2021 Fiscal Year Annual Research Report
二重放物面集束構造を有する導波路型振動子(DPLUS)による医用応用デバイス
| Project/Area Number |
21J10822
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| Research Institution | The University of Tokyo |
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Principal Investigator |
CHEN KANG 東京大学, 新領域創成科学研究科, 特別研究員(DC2)
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| Project Period (FY) |
2021-04-28 – 2023-03-31
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| Keywords | High-power ultrasound / Piezoelectric vibration / Two parabolic reflectors / DPLUS / Therapeutic ultrasound |
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| Outline of Annual Research Achievements |
This research proposes a novel ultrasonic transducer named DPLUS that outputs powerful ultrasound from a thin waveguide using double parabolic reflections, and its basic characteristics are studied.
In this year, the selection criteria of the piezoelectric material for DPLUS were firstly examined. For realizing powerful ultrasound output, the mechanical quality factor and the non-linear vibration characteristics were found as important material indexes. Under a suitable piezoelectric material, the vibration velocity in the DPLUS waveguide can reach around 10 m/s at around 30 kHz and 1.3 MHz, and the acoustic pressure between 1 to 2 MHz can reach 7.3 MPa. It was found that the saturation velocity (10 m/s) in the DPLUS waveguide comes from its material (duralumin), and therefore other materials were proposed such as metal glass and Nitinol. Study of a DPLUS with a 1-mm diameter and 1-m long Nitinol thin waveguide showed that powerful ultrasound can be transmitted through the long waveguide and the waveguide material damping was found as the most important index for improving the vibration output. By delivering the ultrasound to the animal fat, the temperature increases by 10 °C within 30 s, and the fat was melted. Therefore, successful tissue destruction was demonstrated.
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| Current Status of Research Progress |
Current Status of Research Progress
1: Research has progressed more than it was originally planned.
Reason
By studying the selection criteria of the piezoelectric material and waveguide material, high-power ultrasound output of DPLUS has been realized, and the vibration limit in the DPLUS waveguide was revealed.
In addition, therapeutic ultrasound was successfully demonstrated by a DPLUS with a 1-mm diameter and 1-m long Nitinol thin waveguide.
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| Strategy for Future Research Activity |
For a specific application of DPLUS, the optimal design of DPLUS is still unclear. For example, for therapeutic ultrasound, revealing the optimal dimensions of the DPLUS thin waveguide and the optimal working frequency are the important future research directions.
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