超音波治療のための音響ホログラフィによる力場制御

抄録

The formation of a force field in the living body can be useful for medical treatments. For example, when we apply mechanical stimuli to cultured osteoblasts at a low frequency such as 12.5 Hz, the cell proliferation becomes promoted. On the basis of the evidence, mechanical stimuli are expected to promote the healing of fracture. Acoustic holography is a technique of forming an arbitrary-shaped force field in a space by the phase control of waves from each ultrasound transducer. Acoustic holography can be used as a means of forming a force field noninvasively in the living body. In this study, we designed a force field control device by acoustic holography. We determined requirements of the device first to design it. They are that it can control phases of waves from each ultrasound transducer, can change the intensity of force fields at a low frequency, and has more outputs that can levitate objects. Then we chose the hardware to meet the requirements and then produced the device experimentally. Moreover, we focused ultrasound and then applied amplitude modulation at 12.5 Hz. As a result, we realized the diameter of the focal point which was as big as a theoretical one and its output was large enough to affect the living body. Furthermore, we checked we can get sound pressure experimentally which obtains a component of 12.5 Hz in a space where the ultrasound transducer array forms a force field.