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Page 10 of 26 Chen et al. Soft Sci. 2026, 6, 3

Gastrointestinal tract
The GI tract presents a dynamic and chemically diverse environment, comprising anatomically distinct
regions such as the stomach, small intestine, and colon. Each segment poses specific challenges related to
geometry, motility, and biochemical composition. Lumen diameters range from several centimeters in the
stomach to just over one centimeter in the distal intestine. Moreover, peristaltic and segmental contractions
continuously reshape the tract. Chemically, the environment spans a broad pH spectrum, from the highly
acidic gastric lumen to the enzyme- and microbiota-rich milieu of the intestines. These region-specific
physiological conditions impose stringent requirements on the design of magnetic soft robots for GI
applications. To ensure safe navigation and maintain mucosal integrity, robots are typically fabricated from
pH-stable materials such as elastomers and hydrogels [74,75] . Tailoring both material properties and structural
features to the physiological and anatomical context of each GI segment enables magnetic soft robots to
achieve site-specific drug delivery [168-176] , diagnostic sampling [177-179] , and localized therapy [180-182] with improved
safety and therapeutic precision.

In gastric drug delivery, magnetic soft robots provide unique advantages by integrating mechanically
adaptive architectures with magnetic actuation. A representative example is the magnetically actuated
capsule endoscope, designed with elastomeric shells and flexible hinges that passively deform upon contact
with the gastric wall [174] . This mechanical compliance minimizes mucosal irritation and enables stable
locomotion through anatomical constraints. With functional components including internal magnets and
localized drug reservoirs, the capsule enables rolling locomotion driven by magnetic torque for targeted drug
delivery. External magnetic force then induces axial deformation of the capsule body, triggering the release of
the therapeutic payload. To mitigate concerns regarding long-term magnet retention, reconfigurable
miniaturized soft robots have been proposed. Voxel-based magnetic assembly permits fabrication of
submillimeter-scale elastomeric capsules with embedded hard magnetic particles . These microrobots
[60]
realize magnetic rolling and programmable pressure-responsive liquid release. Origami-inspired structural
reconfiguration strategies have enabled the development of foldable gastric robots with multimodal
behaviors [173,175] . Cylindrical Kresling-pattern origami designs incorporating thin magnetic plates demonstrate
reversible folding under rotating magnetic fields, which facilitates rolling locomotion, flipping movements,
and targeted release [Figure 2A]. These robots can actively contract to expel liquid cargo when exposed to
oppositely rotating fields. Their ability to navigate uneven terrains and achieve precise payload deployment
has been validated through ex vivo studies in the porcine stomach. Peristaltic motion in the GI tract can
compress soft capsules, resulting in unintended drug leakage. To address this challenge, a magnetically
driven capsule has been designed with soft valve structures, whose opening and closing are actively regulated
through the interplay of magnetic gradient force and torque to enable controlled drug release . Meanwhile,
[176]
a magnetic actuation strategy based on multifrequency response control allows decoupled regulation of
global capsule locomotion and local valve response, with high-frequency fields triggering localized drug
release while low-frequency fields driving overall motion. This approach minimizes unintended leakage
caused by GI peristalsis while preserving multifunctional capabilities, including targeted drug delivery,
selective dual-drug release, and in situ sampling. Targeted delivery with minimal mechanical disruption
using this system has been demonstrated in rabbit models [Figure 2B]. To address the challenge of poor drug
retention in the GI environment, magnetic soft robots with integrated bioadhesive interfaces have been
developed [75,183] . Tissue adhesion is achieved via both non-covalent interactions (e.g., hydrogen bonding and
electrostatic forces) and covalent bonding. For targeting multiple lesions, a multilayer robot has been
developed for on-demand adhesion to distinct sites in the stomach of a live porcine model .
[75]
Beyond drug delivery, magnetic soft robots have evolved into multifunctional platforms for complex
therapeutic and diagnostic tasks in the stomach. By combining reconfigurable architectures with magnetic
actuation, these devices can navigate confined gastric environments while enabling minimally invasive
interventions [179,182,184] . One key application is autonomous tissue biopsy, where mechanical safety and