Micro ultrasound motor with coiled stator for rotationally driving of ultrasound beam of Intravascular ultrasound imaging system

Abstract

For the purpose of performing radial scanning by rotating ultrasound beam in intravascular ultrasound imaging system for diagnosing the state of thrombus and stenosis in a blood vessel such as the coronary arteries of the heart, we are developing micro Coiled Stator UltraSound Motor (CS-USM). Three types of coiled stators with materials of titanium, stainless steel or copper were prepared. These coiled stators were 5 wound acoustic waveguide with 0.5 mm width and 0.1 mm thickness. Size of coiled stator is 0.9 mm diameter and 3 mm length. PZT ceramic vibrator or hydrothermal PZT film vibrator was employed. When two vibrators-type inner rotor CS-USM having stainless steel coiled stator were driven by voltage of 30Vpp at 311 kHz, rotational speed was 3500 rpm, torque was 0.34μNm. Maximum rotational speed of one vibrator-type inner rotor CS-USM having hydrothermal PZT film was 1100 rpm. Maximum rotational speed of one vibrator-type inner rotor CS-USM with titanium or stainless steel coiled stator was 2400 rpm. Rotational speed of the one vibrator-type inner rotor CS-USM with copper coiled stator driven by same conditions was 3200rpm. Maximum rotational speed of two vibrator-type outer rotor CS-USM with stainless steel coiled stator and PZT ceramic vibrators was 1400 rpm.