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pressure test, which shows that the performance of the magnetically driven flexible gripper will not degrade
in the deep-sea environment. Moreover, the deep-sea biomimetic soft robotic fish studied by Li et al. has
completed experimental testing in the Mariana Trench . The material used in the robotic fish is the same as
[11]
the material used in this study, which further proves that the MSG of this study is applicable to the deep-sea
environment.

Grasping success rates and failure analysis: For each target type, 20 independent grasping trials were
performed and success rates were recorded [Supplementary Table 2]. Overall, the MSG achieved near or full
100% success rates for the majority of targets. Occasional failures were observed in trials using the sea
cucumber model and the mineral model, but success rates for these remained above 90%. Analysis of the
failure cases indicates that failures with the sea cucumber model were primarily caused by insufficient
wrapping of the object during MSG contraction; this can be mitigated by optimizing the spatial distribution
of MSG elements and the wrapping strategy. Failures with the mineral model were mainly attributable to
positional shifts during grasping and to partial nonparticipation of some MSG elements, which reduced the
net grasping force; these issues can be reduced by improving path planning and implementing real time
position correction.

Limitations and future work: Although the present experiments validate the physical integrity and functional
performance of the MSG under the separate extreme conditions of high pressure and low temperature,
constraints of the available facilities prevented testing under combined high pressure and low temperature
conditions. This represents an important limitation of the current study and will be a focus of future work.
Subsequent efforts will upgrade the experimental apparatus to enable systematic evaluation of the MSG in
combined high pressure, low temperature environments, thereby more fully validating its feasibility and
reliability under realistic deep-sea operational conditions.

Limitations of the MSG
However, this study still has some limitations. No actual in-situ deep-sea experiments have been conducted,
and there is a lack of grasping experiments under high pressure and low temperature environments.
Furthermore, the targets grasped in the current experiments cannot completely represent actual deep-sea
targets; therefore, this is a deficiency that needs to be addressed in future research on deep-sea magnetically
driven flexible grasping. Regarding the physical properties of the material, although the quasi-static physical
properties of Ecoflex0020/NdFeB are very stable, research on its dynamic properties is insufficient. Future
research will focus on the dynamic properties of the material. Future efforts will gradually address the
shortcomings of this paper and continuously optimize and improve it.

CONCLUSION
The study developed a rapidly responsive, deep-sea-environment-suitable MSG for efficient and
non-destructive acquisition of mineral and marine biological samples. It shows that the magnetic particle
filling ratio has a significant coupled effect on the mechanical properties of the composite material and the
magnetic drive efficiency, demonstrating a reasonable ratio that balances magnetic responsiveness and
material flexibility. The proposed biomimetic ciliary microneedle structure effectively breaks down water
films and improves underwater frictional stability, thereby increasing the success rate of grasping without
increasing energy consumption. The non-contact magnetic drive method exhibits excellent structural
reliability and dynamic response under the high pressure and low temperature conditions of the deep sea.
This study provides a scalable design concept and technological foundation for the application of MSG in
rapid and non-destructive grasping in the deep sea.

DECLARATIONS
Authors’ contributions
Proposed and designed the research: Yu, S.; Ji, L.; Liang, B.