What is it about?

An ultrasonic lens that passes externally irradiated ultrasonic waves through the skull and focuses them on the affected area within the brain was numerically studied. The proposed acoustic lens is constructed by arranging microbubbles in a suitable arrangement within a water-like substance that covers the head. The placement of the microbubbles is automatically optimized so that the sound field intensity is maximum at the focus of the affected area within the brain and zero elsewhere in the brain.

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Why is it important?

As a noninvasive therapy to promote the effect of the thrombolytic agent in the acute phase of cerebral infarction, transcranial irradiation by ultrasonic waves at the site of the occlusion has been validated and is expected to achieve clinical application. Such irradiation may, however, cause damage to the brain by interference of reflected waves within the skull. That is a serious problem and prevents clinical application. This study found the possibility of realizing an acoustic lens that suppresses the interference of ultrasonic waves within the skull that damages the brain and can track the moving affected part in real time.


At present, I expect that it would be realized with a kind of crossbar switches by introducing an electric current at the target position and there evaporating the water-like substance covering the head with Joule heat to generate a steam bubble. In order to suppress the scattering of ultrasonic waves by the electrode wires of the crossbar switch, of course, it is necessary to make the electrode wires of a material with physical properties similar to those of a water-like substance and to make them as thin as possible. I hope that this paper will serve as an impetus for progress in synthesis technology and microfabrication technology for flexible conductive materials with such properties.

Tsuyoshi Ueta
Jikei University School of Medicine

Read the Original

This page is a summary of: Design concept verification for a transcranial acoustic lens with instantaneous adaptability, Journal of Applied Physics, October 2022, American Institute of Physics,
DOI: 10.1063/5.0101875.
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