A study on the beamforming system with reconfigurable focusing depth for ultrasound-enhanced thrombolysis

In order to dissolve clots within blood vessels located in various parts of the human body with one sonothrombolysis application, the device employed should be able to control the focal depth where acoustic energy is focused. This paper presents such an ultrasound beamforming system with reconfigurable focal depth. It consists of an annular piezoelectric micromachined ultrasonic transducer (pMUT) array of 1 cm radius, and a beamforming unit that is composed of an ARM processor and a driving circuit. The measured peak intensity at the focal point of 13 mm is 1.35 W/cm², and the average intensity of the -3 dB focal dimension from the peak intensity is 933 mW/cm. The proposed system operating at 1.21 MHz could be used for ultrasound-accelerated thrombolysis with an intensity that is above typical diagnostic levels at the focusing point, and also with a reconfigurable focusing depth.