Feasibility study of a membrane-type magnetostrictive acoustic transducer for ultrasonic thrombolysis

摘要

It is well known that ultrasound helps increase the efficiency of thrombolysis when used together with tissue plasminogen activators. Recently, a catheter device mounting a piezoelectric ultrasound transducer on its tip has been proposed. However, this device has some limitations because the supply of high-voltage electric power to piezoelectric elements in the transducer can be dangerous to a human. To overcome this limitation, the use of a magnetostrictive acoustic transducer instead of piezoelectric one was considered. A magnetostrictive transducer can generate ultrasound by the magnetic field not by electric field. In this work, we propose a magnetostrictive transducer and investigate its feasibility as a device for thrombolysis. Specifically, the membrane shaped element was considered instead of a cylindrical block since it is easily made of a nickel or Fe-Co alloy thin plate having strong magnetostriction. For experiments, the transducer was submerged under water and, then, the velocity of water surface was measured by a laser vibrometer to evaluate the near field acoustic wave from the membrane. The results show that the membrane vibration can be effectively transferred into acoustic waves in water. This result confirms that the proposed transducer has strong potential for ultrasonic thrombolysis without electric current flow into a body.