By Soham NandiReviewed by Lily Ramsey, LLMApr 18 2025In a recent article published in Nano-Micro Letters, researchers introduced an untethered, magnetically controlled soft robot that combines phase-changing magnetic composites with flexible electronics. This system enables reversible shape-morphing and a variety of movements while maintaining stable electrical functionality during motion.
Demonstrations showed its adaptability for complex tasks like navigation and optoelectrical sensing in dynamic environments. Thanks to its integrated design, the robot retains mechanical flexibility without sacrificing electronic performance, which has been validated through experiments and theoretical modeling.
Potential applications range from biomedical implants for in situ monitoring and therapy to environmental sensing devices. Future developments aim to miniaturize and enhance material performance.
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Background
Soft robotics has quickly become a key platform for biomedical and environmental systems, thanks to its use of compliant materials that integrate smoothly with biological tissues. Previous efforts have produced both non-invasive technologies, such as electronic skin, and invasive tools, like bioresorbable implants.
Among the most promising approaches are magnetically actuated soft robots, which offer precise, untethered control and the ability to perform a range of motions.
However, existing systems often fall short and are limited either to simple movements or are reliant on bulky external components for sensing and stimulation. These additions create mechanical mismatches that limit real-world functionality.
This study addresses those limitations by presenting a fully integrated soft robot that combines magnetically responsive composites with stretchable, multifunctional electronics. The system allows reversible shape programming, wireless operation, and interactive environmental sensing, all in a cohesive mechanical framework.
By integrating actuation and electronic functionality, the design sets a new benchmark for multifunctional soft robotics, with promising implications for next-generation implants and adaptive monitoring systems.
Materials Synthesis and System Integration
The team outlined a detailed fabrication process for their integrated magnetic soft robot. At the core of the system are wax-coated magnetic particles (WcMPs), made by treating neodymium iron boron (NdFeB) microparticles with silane, mixing them with molten soybean wax, and rapidly cooling the mixture for encapsulation.
These WcMPs were then embedded in a silicone elastomer to create programmable magnetic composites. These composites were laser-patterned and aligned under magnetic fields at temperatures above 45°C.
To characterize the material, the researchers used optical microscopy, mechanical tensile testing, and magnetic property measurements via a SQUID-vibrating sample magnetometer (SQUID-VSM).
The full robotic system was built through a multilayer assembly: copper radiofrequency (RF) coils were patterned onto a PDMS substrate, layered with a dielectric, and integrated with components using silver epoxy. The structure was then encapsulated in Ecoflex for protection and flexibility.
Integrated electronics included microscale LEDs (μ-LEDs), Bluetooth modules, and a variety of sensors. The robot was actuated using both permanent magnets and custom electromagnets, achieving controlled movement through specific 3D magnetic field patterns at frequencies up to 2.5 Hz.
The system’s electrical stability was thoroughly tested under magnetic fields up to 200 milliTesla (mT), with repeated cycles confirming durability. Researchers also measured wireless power transfer efficiency, I–V characteristics of the sensors, and thermal behavior using tools like vector network analyzers and infrared cameras.
The fabrication process effectively merged soft magnetic actuation with robust, flexible electronics into one unified platform, showcasing stable performance under dynamic conditions without compromising sensing or control.
Results and Discussion
The robot consists of a soft ferromagnetic matrix—Ecoflex combined with wax-coated NdFeB particles—and flexible electronics, including an RF coil, sensors, and a Bluetooth module, all encapsulated in a silicone layer.
The wax coating allows for magnetic reprogramming at just 45°C, enabling the robot to reshape into complex forms (like the letters L, Z, and S) under external magnetic fields between 150 and 200 mT. A decentralized serpentine circuit layout helps reduce mechanical strain, allowing bending behavior like that of magnetic actuators alone.
It supports multiple modes of locomotion—crawling, rolling, and rotating—controlled by varying the magnetic field’s strength (0–200 mT) and frequency (0–2.5 Hz). Both theoretical models and real-world tests confirmed consistent electronic performance during these movements, with less than 3% variation in actuator and sensor functions under magnetic loads up to 200 mT.
Wireless power transmission remained effective at the system’s 6.78 MHz resonant frequency, even during significant deformation.
The robot’s real-world capabilities were demonstrated in a dynamic obstacle course. It could fold to pass through tight spaces, reroute around heated objects using temperature feedback, and return to its original shape afterward.
Real-time Bluetooth data transmission, coupled with reliable operation in both wet and dry environments, underscored its robustness and adaptability.
Conclusion
This study presents a compelling demonstration of a fully integrated soft robotic system that combines magnetically responsive materials with stretchable electronics for untethered, adaptive operation.
By utilizing WcMPs for low-temperature magnetic reprogramming and a decentralized circuit design, the robot achieves complex shape-morphing while maintaining stable wireless function in magnetic fields up to 200 mT.
Its ability to maneuver through obstacles, send real-time sensor data, and preserve electronic functionality during deformation makes it a strong candidate for biomedical implants and responsive environmental monitors.
By eliminating mechanical compromise and consolidating multiple functions into one soft, cohesive system, the work addresses critical challenges in soft robotics and opens new pathways for multifunctional, adaptive machines.
Journal Reference
Han et al., (2025). Wireless, Multifunctional System-Integrated Programmable Soft Robot. Nano-Micro Letters, 17(1). doi: http://dx.doi.org/10.1007/s40820-024-01601-3. https://www.eurekalert.org/news-releases/1079784
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