For decades, the vision of medical microrobots navigating the bodily highways to perform targeted interventions has remained clinically elusive, due to the difficulty in achieving robust navigation and controlled deployment without escalating device complexity or depending on physical tethers. This thesis embarks on a journey to overcome this limitation through a design paradigm where navigation and intervention are architecturally separated, and device intelligence is relocated from onboard electronics to externally applied physical fields.
The systems developed in this paradigm rely on a dual-stimuli stack of magnetics and near-infrared light to decouple navigation from intervention. Magnetic fields provide deterministic, long-range spatial positioning within biological environments, while near-infrared (NIR) irradiation triggers localized, on-demand morphological transformation through shape memory polymers only after the device has reached its target. By assigning movement to magnetics and function to light, the proposed devices remain mechanically simple, wirelessly controlled yet therapeutically capable without any on-board electronics.
This philosophy is realized through two complementary platforms addressing disease within two of the most critical bodily conduits, the gastrointestinal and endovascular tracts. In the gut, the Magnetic Endoluminal Deposition System (MEDS) targets conditions such as gastric hemorrhage and ulcers by enabling untethered, in-situ bioprinting directly over the disease site. Leveraging magnetically modulated stickâ slip dynamics for controlled locomotion and patterned bioink deposition, MEDS demonstrates precise surface coverage and localized therapeutic delivery within compliant gastric environments.
In the vasculature, the Magnetic Endovascular Morphing System (MEMS) addresses cerebral aneurysms and tumour feeder vessels, where uncontrolled flow poses rupture risk. Magnetically guided microdevices are navigated through tortuous anatomy and upon near-infrared activation, deploy as flow disrupting structures to modulate intra-luminal hemodynamics. A flow-responsive magnetically modulated stickâ slip framework captures navigation under pulsatile conditions, while particle image velocimetry and computational modelling confirm significant suppression of flow metrics in target sites.
Thus, by elegantly separating locomotion from function, this thesis lays the groundwork for a new generation of meso-scale tools, thereby taking one small step toward Feynman's long-envisioned "swallowable surgeon".
