A Miniature Rotary-linear Ultrasonic motor for Intravascular Ultrasound (IVUS) Imaging

Existing intravascular ultrasound (IVUS) systems basically make use of two motors to rotate and pull back the single-element transducer to realize three-dimensional (3D) vascular imaging. In order to realize 3D helical ultrasonic scanning, this study proposes a novel approach for an imaging catheter, which is driven by a miniature rotary-linear ultrasonic motor. The proposed approach is introduced because mechanical scanning devices are bulky, and electromagnetic motors cause electromagnetic interference. The motor utilizes two orthogonal bending modes to generate helical motion without utilizing any other transmission structure. The rotor and stator are connected using threads, and the axial and circumferential motions are coupled to reach a compact size (maximum diameter of 8 mm and a longitudinal length of 20 mm). In addition, to evaluate the performance of the proposed IVUS system, we conducted imaging of a wire phantom and tissue agar phantom. This work proves that an imaging catheter driven by an ultrasonic motor holds promise for generating smooth and precise 3D IVUS images.