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Yu et al. Soft Sci. 2026, 6, 19 Page 5 of 24

digital multimeter, purchased online, manufactured by ITECH Electronics Co., Ltd.; magnetometer,
purchased online, manufactured by ADEX Instruments Co., Ltd.; sealed high-pressure chamber,
custom-fabricated, manufactured by Shenzhen Dinghai New Materials Technology Co., Ltd.

All images were created using COMSOL, Solidworks, PowerPoint, Origin and Premiere Pro.

RESULTS AND DISCUSSION
Design rationale, application scenarios and actuation principle of the MSG
Soft actuators, particularly soft grippers, have shown great promise for underwater inspection, biological
sampling, and resource collection. Conventional rigid manipulators or soft grippers driven by tethered
pneumatic/hydraulic systems commonly suffer from slow response, bulky hardware, the risk of damaging
delicate targets, and potential leakage/pollution in complex subsea environments. Magnetic soft grippers
offer an effective alternative to these approaches due to their non-contact actuation, rapid response,
structural simplicity, and environmental compatibility. Focusing on operation in complex underwater
settings, this study proposes and designs a novel MSG [Figure 1] aimed at safe, efficient, and non-destructive
grasping of marine organisms (e.g., fragile flora and agile fauna) as well as morphologically irregular
deep-sea mineral nodules (e.g., polymetallic nodules). As illustrated in Figure 1A, the diversity of target
properties-fragility, mobility, and irregular geometry-places stringent demands on gripper adaptability,
compliance, and grasp stability. The core concept is to exploit remotely applied magnetic fields to induce
precisely controlled deformation of soft structures, thereby avoiding the limitations associated with
physically tethered actuation.

The gripper body adopts a modular, bioinspired multi-finger architecture [Figure 1B], where each finger is
assembled from a series of serially connected modules. Each module comprises three principal elements: (1)
a magneto-responsive matrix consisting of a soft silicone elastomer (e.g., Ecoflex0020) embedded with
high-performance NdFeB particles, which senses external magnetic fields and produces the active
deformation; (2) an internal skeleton that links adjacent modules and provides necessary load-bearing
support (analogous to a biological bone), ensuring structural integrity under external loads while allowing
the magnetic matrix to remain conformal to the skeleton; and (3) biomimetic ciliate-like microneedle arrays
distributed on the contact surface to increase surface roughness and friction. The microneedle surface is
especially important for overcoming underwater lubrication effects-such as mucous coatings and water
film-thereby improving grip reliability and slip resistance.

The actuation system is based on an externally controlled electromagnetic field [Figure 1C]. By precisely
programming the coil current (magnitude and polarity), a spatially tunable field and gradient can be
generated around the gripper. The external field interacts with the embedded NdFeB particles to induce
magnetic moments and to apply magnetic forces and torques, driving controllable bending deformations
(opening/closing) of the soft modules. This actuation paradigm brings several key benefits: remote,
non-contact control that eliminates physical connections (e.g., hydraulic lines or pneumatic tubing) and thus
mitigates sealing and leakage failures-an advantage for confined, high-pressure, or contamination-sensitive
subsea operations; millisecond-scale theoretical response enabled by the near-instantaneous transmission of
magnetic fields, outperforming fluidic or thermally driven systems for capturing fast-moving organisms;
high system integration and low end-effector mass, since the coils may be mounted externally or on the
carrier vehicle while the gripper itself contains only soft material and magnetic filler; and fine programmable
control over deformation amplitude, speed, and shape, allowing adaptation to objects of varying size,
geometry, and mechanical properties. Experimental results show that the MSG can complete an underwater
grasping action within 0.4 s, and can rapidly, safely, and reliably capture five representative targets, including
live turtles (mobile organisms), algal balls (fragile organisms), and irregular mineral samples, and all