Page 17 - Read Online

Page 14 of 26 Chen et al. Soft Sci. 2026, 6, 3

limited access to distal or tortuous vasculature, procedural invasiveness, and risks of vascular perforation.
Furthermore, systemic pharmacotherapies, such as anticoagulants and thrombolytics, are frequently
hindered by off-target effects and an increased risk of haemorrhagic complications, highlighting the need for
more precise and minimally invasive vascular interventions. Magnetic soft robots have emerged as a
promising modality to address critical limitations associated with traditional catheter-based approaches and
systemic pharmacological therapies [76,94,190-194] . They allow robots to access distal anatomical sites and perform
localized therapeutic tasks such as targeted drug release [77,94,195] , thrombus extraction [191,196] , and controllable
embolization [78,197] .

To complete targeted delivery, a stent-like magnetic soft robot has been developed for remote navigation and
therapy in M4 segment of the middle cerebral artery . The robot incorporates a flexible, morphologically
[77]
adaptive body with shape-memory polymer components. Successful traversal through vascular phantoms,
including luminal constrictions to 1.0 mm, bifurcations up to 120°, and physiologically relevant pulsatile flow
velocities (~ 26 cm/s) has been demonstrated. Upon reaching the target location, wireless radiofrequency
stimulation induces localized thermal activation, triggering on-demand drug release from encapsulated
reservoirs [Figure 4A]. Additionally, the porous architecture enabled the device to function as a dynamic
flow diverter, redirecting hemodynamics away from pathological regions such as aneurysmal sacs or
malformed branches. This design integrates mechanical, therapeutic, and hemodynamic functions in a single
platform.

Thrombus formation remains a major pathological mechanism of cardiovascular and cerebrovascular
disease, contributing to high morbidity and mortality. Soft robotic systems have been developed to perform
both pharmacological and mechanical thrombectomy through magnetically controlled adaptive deformation.
A representative design employs ferromagnetic liquid composed of Fe O nanoparticles dispersed in
4
3
dimethyl silicone oil, demonstrating robust deformation and navigation through synthetic vasculature
models with tortuous geometries and lumens as narrow as 0.5 mm. The robot exhibits magnetically tunable
stiffness, with increasing magnetic field intensity enhancing its structural rigidity to facilitate active thrombus
displacement, which has been validated in rabbit ear vein models [128] . A reconfigurable soft robot
accomplishes thrombus removal through mechanically driven penetration and hooking of the clot [Figure
[191]
4B]. Under rotating magnetic fields (10 mT, 40 Hz), the robot effectively engaged and removed plasma clots
in a vein-mimicking phantom, achieving complete thrombus extraction in three minutes without fibrinolytic
agents. Compared with conventional catheter-based or balloon-assisted thrombectomy, soft robotic
approaches offer reduced procedural trauma and superior adaptability to delicate or irregular vascular
anatomies.

Magnetic soft robots also show significant potential in vascular embolization to reduce blood flow in
pathological regions such as aneurysms or tumors [78,197] . Microfiber-based devices, fabricated through thermal
drawing of magnetic elastomer composites, demonstrate helical propulsion under rotating magnetic fields.
Their design enables reversible shape transformations between elongated and aggregated states, facilitating
precise modulation of embolic behavior. In addition, under physiologically relevant flow conditions, the
microfiber robot demonstrated stable anchoring and effective helical propulsion within vascular
environments. Driven by a 40 mT rotating magnetic field, it achieved upstream and downstream propulsion
velocities of 0.32 mm/s and 1.75 mm/s, respectively, at a flow rate of 100 mm/s, confirming its capability for
active locomotion and precise control under realistic blood flow. The microfiber robot also exhibited robust
anchoring performance, maintaining stability against flow velocities of approximately 200 mm/s. These
microfiberbots successfully performed targeted embolization in vitro inside aneurysm- and tumor-
mimicking phantoms. Their efficacy has been validated through in vivo embolization of the rabbit femoral
artery, guided by real-time fluoroscopic imaging [Figure 4C]. This platform represents a progress in
[78]
embolization strategy, allowing minimally invasive, spatiotemporally precise blood flow occlusion.