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Chen et al. Soft Sci. 2026, 6, 3 Page 5 of 26

Table 1. Classification of magnetic soft materials
Elastic
Type of Example modulus Main
magnetic soft (Soft matrix + magnetic Key properties Biostability (Young’s applications Refs.
materials fillers)
modulus)
High-water content
Biocompatibility
Magnetic Alginate + Fe 3 O 4 /NdFeB Biological tissue Degrades in Cell manipulation
hydrogel softness alkaline 10-100 kPa Drug delivery [74,85,88,97-99]
Lower mechanical environments
strength
Degrades in
alkaline 40 kPa
Carrageenan + Fe 3 O 4
environments
Dissolves at
body 2.86 MPa
Gelatin + Fe 3 O 4
temperature
Stable and
Poly(vinyl alcohol) + NdFeB difficult to 2.72-5.14
degrade MPa
Magnetic-driven
Mechanical
Silicone-based Stable and actuators Cargo
magnetic PDMS + NdFeB compliance difficult to 10 kPa-20 delivery [57,75,76,112]
elastomer Ecoflex + NdFeB High elastic strain degrade MPa Minimally
Biocompatibility
invasive surgeries
Controlled
reconfigurability Magnetic-driven
Ferrofluids Kerosene oil + Fe 3 O 4 Extreme NA NA actuators [116,119,122]
deformability Cargo delivery
Mineral oil + Fe 3 O 4
Toxic
Controlled
reconfigurability Degrades under
Extreme lipase activity [125]
Corn oil + Fe 3 O 4
deformability and oxidation
Biocompatibility
[128]
Silicone oil + Fe 3 O 4
Shape memory
polymer resin + MPa
Magnetically Shape NdFeB Shape fixation (rubbery Magnetic-driven
responsive memory Acrylate-based Stimuli-responsive Biodegradable state) → actuators [133,134]
active polymers amorphous Biocompatibility GPa (glassy Cargo delivery
composites
polymer + state)
NdFeB
Shape fixation
Stimuli-responsive
Liquid crystal elastomers + Magnetic
NdFeB reprogrammed NA [136-138]
Reversible large
deformation

NA: Not available.

under an applied magnetic field. These features enable reconfiguration of the soft robots in confined or
torturous biological environments, such as vascular or GI lumens. Their inherently low viscosity and soft
interfacial compliance enable minimally invasive and atraumatic interactions with soft tissues, making them
ideal for short-term biomedical interventions [123-127] .

Ferrofluid-based soft robotic systems have been engineered into diverse configurations, including liquid
capsules for targeted cargo delivery, omnidirectional ciliary matrices for wireless biofluid pumping, and
adaptive liquid skins for constructing microscale soft machines [123] . However, the presence of unbound
magnetic nanoparticles leaked from ferrofluid raises significant concerns regarding systemic toxicity, long-
term biodistribution, and accumulation in critical organs such as the liver, spleen, and brain. Moreover,