Robust and Fast-Transforming Soft Microrobots Driven by Low Magnetic Field.

Area of Science:

• Soft robotics
• Materials science
• Nanotechnology
• Magnetic actuation

Background:

• Soft microrobots offer advantages like maneuverability and biocompatibility but face challenges in balancing mechanical stability and responsiveness.
• Low-power actuation is desirable for microrobot safety and cost-effectiveness, relying on precise magnetic domain control.
• Traditional multi-domain magnetic microstructures often compromise performance.

Purpose of the Study:

• To present a magnetic domain assembly method for fabricating robust soft microrobots.
• To achieve fast transforming behaviors in microrobots using low magnetic fields.
• To overcome the trade-offs between mechanical stability and responsiveness in traditional microrobot designs.

Main Methods:

• Fabrication of a composite ink with polyacrylamide chains grafted onto single-domain ferromagnetic NdFeB nanostructures.
• Utilizing magnetic field-assisted 3D printing to achieve precise control over magnetic domain orientation in ultrafine filaments (80 µm).
• Characterization of microrobot properties, including actuation speed, mechanical toughness, and stretchability.

Main Results:

• Uniform magnetic alignment enabled complex and rapid shape morphing in under 1 second, even with low NdFeB content (less than 2 wt.%).
• Achieved a tenfold increase in mechanical toughness and 1600% stretchability due to uniform magnetic alignment.
• Demonstrated top-performing actuation at low magnetic fields (3-15 mT), showcasing multimodal locomotion and tasking capabilities.

Conclusions:

• The magnetic domain assembly method successfully creates robust soft microrobots with fast transforming behaviors powered by low magnetic fields.
• This approach enhances mechanical properties and actuation performance, overcoming limitations of traditional microrobot designs.
• The developed microrobots show significant potential for next-generation soft robotics applications.