Design and fabrication of an electromagnetic micro-motor for intravascular ultrasound (IVUS) imaging

Catheter based intravascular ultrasound (IVUS) imaging is widely used for coronary artery diseases. However, image produced by the current IVUS catheter which utilizes an outer proximal motor and a flexible drive shaft transmitting rotational motion through the bending vessel segment, is easy to distort. In this study, we present an electromagnetic micro-motor as a distal actuator for IVUS imaging. The micro-motor consists of a two-pole permanent magnet as the rotor and two-strand flexible coils as the stator. The size of the prototype electromagnetic micro-motor is 6.4 mm length and 1.5 mm outer diameter. The rotational speed of the micro-motor was characterized by using a laser displacement sensor. The micro-motor can generate several decade revolutions per second (RPS) speed needed for IVUS imaging. A static 3D electromagnetic simulation of the micro-motor was performed to estimate the driving torque. The micro-motor can generate a torque of 14.5 µNm with 1.0A effective driving current. This micro-motor is expected to eliminate the image distortion.