A 3D-printed microfluidic device for fabricating the soft, hollow, double-network magnetic microrobots

Endovascular intervention has transformed minimally invasive surgery but faces challenges in device stiffness, navigability, and safety. Existing magnetic soft robots, while promising, often risk incomplete retrieval or lack structural adaptability for controlled drug delivery. Here, we present a 3D-printed microfluidic strategy to fabricate a hollow magnetic soft robot (HMSR) with a double-network hydrogel structure (ionically crosslinked sodium alginate and photopolymerized PEG-diacrylate) and customized magnetic particle distribution. The HMSR exhibits ultralow stiffness (2–3 orders of magnitude lower than commercial guidewires), tunable mechanical properties via component concentration and UV exposure, and hollow architecture for drug loading. A magnetic navigation platform enables precise maneuvering through complex vascular models (achieving ± 135° bending angles) and multi-path selection, with full retrieval capability to mitigate embolism risks. Drug release kinetics demonstrate rapid initial release (30-min burst phase) followed by sustained release (60-min maintenance), ideal for thrombolytic or chemotherapeutic applications. This work advances magnetic soft robotics for safer endovascular therapies.