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Page 2 of 26 Chen et al. Soft Sci. 2026, 6, 3

INTRODUCTION
Soft materials with mechanical compliance, deformability, and tunable responsiveness constitute essential
components of medical soft robots . These materials enable diverse motions, such as bending, folding, and
[1-5]
crawling, enhancing adaptation to dynamic environments, especially in confined anatomical regions [6-10] .
Their tissue-matching elastic moduli ensure safe interaction with delicate biological structures, minimizing
mechanical irritation and inflammatory responses [11,12] . To achieve remote operation within the body, various
actuation strategies have been explored, including magnetic [13-17] , light [18-23] , acoustic waves [24-29] , chemical
reactions [30-39] , and thermal stimuli [40-43] . Among these approaches, magnetic actuation is particularly
advantageous for biomedical applications [13,14,44-51] . First, biological tissues and organs exhibit high
transparency to magnetic fields. Second, magnetic fields can be remotely applied without causing noticeable
harmful effects on biological systems. Additionally, precise control can be achieved through tuning the
parameters of magnetic fields, enabling real-time navigation and functional manipulation of soft robotic
systems in vivo.

Magnetic soft robots typically consist of polymeric matrices embedded with magnetic particles [52-56] . The
spatial arrangement of these particles defines the magnetization profile and governs deformation and
locomotion. Advanced fabrication techniques - including template-assisted synthesis , 3D printing-assisted
[57]
patterning [58,59] and microassembly [60-62] - optimize particle distribution to generate complex magnetization
profiles. These profiles enable multimodal locomotion, such as rolling [63,64] , crawling , walking [57,65] , and
[57]
swimming [66-69] , and programmable shape morphing for grasping , folding [59,61] , elongation , and
[70]
[57]
twisting . While these capabilities provide a versatile foundation for biomedical applications, their
[71]
successful operation in vivo requires tailored adaptation to the specific physiological conditions of target
organs. To meet these requirements, magnetic soft robots employ specific functional materials, structural
designs, and programmable magnetization profiles to navigate complex physiological environments safely
and effectively. For example, soft catheters with programmable magnetization profiles enable adaptive
navigation through complex luminal environments, including the esophagus, blood vessels, and urethra,
enhancing maneuverability while minimizing mechanical contact with surrounding tissues . Moreover, the
[72]
organ-specific material design of these robots further ensures biosafety and biochemical compatibility [12,73] .
For gastrointestinal (GI) applications, materials such as silicone elastomers and hydrogels have been
employed due to their chemical stability and resistance to acidic or alkaline fluids and enzymatic
degradation [74,75] . In vascular environments, applying a lubricious hydrogel coating to the soft polymer matrix
can substantially reduce mechanical trauma during navigation . The stent-shaped and helical-shaped [78]
[76]
[77]
robots effectively reduce hydrodynamic drag and facilitate controlled locomotion within confined vascular
channels when the magnetic driving force exceeds the combined resisting forces, including viscous drag from
the surrounding fluid and frictional interactions at the vessel wall. Such designs allow the robot to sustain
propulsion and perform controlled interventions in physiologically relevant flow conditions. Overall,
integrating materials, structural architecture, and actuation strategies facilitates safer and more effective
performance of magnetic soft robots in vivo.

To ensure a comprehensive and unbiased synthesis of the field, we conducted a structured literature search
across Web of Science, Scopus, and PubMed. The primary keywords used included “magnetic soft robot”,
“magnetic soft materials”, “ferrofluid robot”, and “biomedical soft robot”. The results were filtered to include
proceedings, articles, and review articles. We focused on peer-reviewed articles published within the past ten
years, prioritizing studies that reported advances in material development, magnetic actuation strategies,
organ-specific design principles, or biomedical applications in vivo or in clinically relevant models. Existing
reviews focus on the actuation mechanisms and functionalization strategies [79,80] of the materials and soft
components used in magnetic robots or the design, fabrication strategies, and biomedical applications of
magnetic soft robots [9,81,82] . Since they lack an organ-centric perspective and clinical translation of magnetic
soft robots depends on their capability to adapt to organ-specific challenges such as dynamic luminal