Ultrasound-Guided Wired Magnetic Microrobot With Active Steering and Ejectable Tip

Interventional therapy is popular in modern surgical procedures for the treatment of vascular diseases. However, it remains challenging to smoothly steer the guidewire/catheter into distal tortuous lumen environments. In this article, a wired magnetic microrobot (WMM) is proposed for approaching hard-to-reach regions. The WMM consists of a commercial guidewire and an assembled tip module, which has two working modalities with a magnetically triggered switch. The tethered mode has high efficiency and reliability, where the forward-backward motion is controlled by the feeding device and the steering motion is actuated by the directional external magnetic field. The untethered mode has enhanced flexibility, where the ejected helical bullet is wirelessly propelled by the rotating external magnetic field. A homemade actuation system is adopted for large-workspace magnetic control and medical imaging-based feedback. Targeted scanning is conducted based on real-time segmentation of the vessel region in ultrasound (US) images and estimation of the vascular distribution. Both transverse and longitudinal views are used for visual tracking under different modes. With the proposed system, the WMM can be navigated in a 3-D tubular structure over a distance of 1000 mm, and the whole procedure can be performed under US imaging monitoring.