Magnetic soft robots are spread like butter

Magnetically actuated mobile robots demonstrate attractive advantages in various medical applications due to their wireless and programmable executions with tiny sizes. Confronted with complex application scenarios, however, it requires more flexible and adaptive deployment and utilization methods to exploit the functionalities brought by magnetic robots fully. To address this issue, the research team of the University of Macau reports a design and utilization strategy of magnetic soft robots using a mixture of magnetic particles and non-Newtonian fluidic soft materials to produce programmable, hardened, adhesive, reconfigurable soft robots. The team published their findings in Research on October 18, 2023 (https://spj.science.org/doi/abs/10.34133/research.0262).

Wireless-actuated magnetic soft robots can reach deep tissue and corners within the human body, and their real-time navigation inside the human body plays a significant role in the precise treatment of patients in the biomedical field. However, for actual clinical applications, there remain limitations in medical assignments in vivo when only relying on magnetic miniature robots, owing to limited functionalities and self-performance parameters such as output force and structure stiffness. These inherent disadvantages prevent medical development and research, requiring more flexible and adaptive deployment and utilization strategies. It remains a challenge to enable these miniature magnetic robots to finish complex assignments by themselves. The synergistic development of magnetic tiny robots with existing medical devices is promising and practical to introduce these new findings into clinical applications as quickly as possible.

In response, researchers have reported a design and utilization strategy of magnetic soft robots using a mixture of magnetic particles and non-Newtonian fluidic soft materials to produce programmable, hardened, adhesive, reconfigurable soft robots. For deployment, their ultrasoft structure and adhesion enable them to be spread on various surfaces, achieving magnetic actuation empowerment. The reported technology can potentially improve the functionality of robotic end-effectors and functional surfaces. Experimental results demonstrate that the proposed robots could help to grasp and actuate objects 300 times heavier than their weight. Furthermore, it is the first time to enhance the stiffness of mechanical structures for these soft materials by on-demand programmable hardening, enabling the robots to maximize force outputs.

However, it is challenging to utilize such ultrasoft robots to provide sufficient output forces as well as demonstrate reliable stiffness at the same time. To enable the proposed robots' fast switching between liquid and solid, the researchers utilized a mixture of magnetic particles and non-Newtonian fluidic soft materials to produce robots whose non-Newtonian properties can be well activated by external magnetic fields, namely, on-demand hardening. In addition, the adhesion can also be controlled by the same means. Thus, the soft robots can flexibly work in collaboration with current medical equipment. "These findings offer a promising path to understanding, designing, and leveraging magnetic robots for more powerful applications," said Qingsong Xu, a Professor at the Department of Electromechanical Engineering, University of Macau.

The research team's experimental results show that using a mixture of magnetic particles and non-Newtonian fluidic soft materials to produce magnetic soft robots can achieve programmable hardening, controlled adhesion, soft reconfiguration, and other properties. With the help of an external magnetic field, through the adhesion and magnetic actuation of the soft robot, a 1-gram soft robot can pick up an object 300 times its weight. The soft robot can adhere to various surfaces, giving it the ability of magnetic actuation for improved performance. When used with traditional surgical robots, the soft robots provide precise magnetic navigation and control and a wider range of functions, including adhesion grasping and related operations. In addition, the non-Newtonian properties of the soft robot can be activated wirelessly by applying a rapidly changing external magnetic field, enabling fast hardness switching, which can be controlled in real time between fluid and solid forms.

There are three authors of the study, the only corresponding author is Prof. Qingsong Xu. The other two main authors are Mr. Zichen Xu, a doctoral student of the School of Science and Technology of the University of Macau, and Mr. Yuanhe Chen, a doctoral student of the School of Science and Technology of the University of Macau. The research was supported by the National Natural Science Foundation of China (File no. 52175556), the Macao Science and Technology Development Fund (File no. 0102/2022/A2, 0153/2019/A3, and 0004/2022/AKP ), and the University of Macau (File no. MYRG2022-00068-FST and MYRG-CRG2022-00004-FST-ICI).