Modular magnetic microrobot system for robust endoluminal navigation and high–radial force stent delivery in complex ductal anatomy

Endoluminal stent implantation is a common intervention strategy for treating obstructive lesions, but conventional delivery systems struggle to reach deep, tortuous ducts. To overcome this limitation, we present a magnetically controlled microrobot that integrates two functional modules: a magnetic actuation (MA) module for agile navigation and an ultrasound-responsive self-expanding stent module (ST module) for lesion-specific dilation. The system uses a dynamically tunable assembly mechanism governed by rotational direction enabling integrated locomotion (clockwise) and on-demand module separation (counterclockwise) at stenotic sites. The platform is compatible with intraoperative ultrasound, allowing real-time navigation and thermally triggered expansion in physiological environments. By synergizing programmable magnetic actuation, ultrasound-mediated expansion, and clinical workflow compatibility, the robot can navigate tortuous phantom ducts, achieving controlled stent deployment within 3 seconds and complete expansion within 30 seconds, permitting minimally invasive treatment of biliary strictures. This work advances microrobotic stent delivery by overcoming key barriers to clinical translation in endoluminal interventions.