Electronic quality factor control for piezoelectric transducer arrays

Abstract

In recent years, many therapeutic applications for medical ultrasound have arisen, such as ablation of tumors, breaking up kidney stones, and neuromodulation. To localize the target area, often ultrasound imaging methods are used. Conventionally, a different transducer array is used for imaging and therapeutic applications because of their conflicting requirements of transducer damping. If this damping would be done electronically, it can be switched on or off on demand, allowing a single transducer array to be used for both therapeutic and imaging ultrasound. This would allow medical ultrasound devices to be smaller and therapeutic treatments to have reduced overall system complexity. This thesis develops a PCB to compare a combination of existing and novel methods of electronic damping on a single transducer, also called electronic Q-factor control. A maximum damping of 23\% is achieved relative to the undamped transducer mounted on the PCB. This is achieved by a novel method based on a feedback loop around a second 'dummy' transducer. Methods of electronic Q-factor control should eventually be extended to be applied in an Integrated Circuit for damping of entire ultrasound transducer arrays.