Magnetic Shaftless Propeller Millirobot Shows Promise for Thrombosis Treatment and Targeted Drug Delivery

Their potential applications in areas like thrombosis treatment, drug delivery, and endoscopic examinations hold significant value. However, most existing magnetic miniature robots perform well only in specific environments. Some robots excel in liquid environments, while others move efficiently on solid surfaces, but few can operate effectively across multiple environments simultaneously. Furthermore, precise fluid handling capabilities—such as the accurate control of fluid and particle transport—are essential for medical and biomedical applications. Now, scientists have proposed a new type of magnetic shaftless propeller-like millirobot (MSPM), which can achieve rotating-based multimodal 3-dimensional motion and cargo transportation with untethered manipulation.

In a new study, scientists from Beijing Institute of Technology (Beijing, China) set out to develop an MSPM capable of multimodal motion and fluid manipulation across diverse environments. The robot is designed with two primary components: the magnetic propeller and the non-magnetic supporting part. The magnetic propeller generates propulsion through the interaction with a rotating magnetic field, while the non-magnetic supporting part ensures stability and provides structural support. The magnetic propeller is made from a mixture of polydimethylsiloxane (PDMS) and neodymium-iron-boron (NdFeB) magnetic particles.

The design of the propeller, inspired by a shaftless water pump, allows it to generate effective propulsion in liquid environments. The propeller features three blades, each measuring 1.3 mm in height, 2 mm in width, and a 45° tilt angle, enabling the robot to generate movement and fluid transportation capabilities when influenced by a rotating magnetic field. The supporting part is constructed from Ecoflex 00-30 silicone rubber, designed in a ring shape with a 3.6 mm diameter, 2 mm width, and 100-micrometer thickness. This design provides essential support while maintaining flexibility, allowing the robot to adapt to various motion modes.

The research, published in the journal Cyborg and Bionic Systems, demonstrates the successful development of the MSPM, which integrates multimodal motion and fluid manipulation. By harnessing the interaction between the robot’s propeller and its external environment, the robot is capable of multiple motion modes, including rolling, propelling, and tumbling, across different terrains. Additionally, the robot effectively transports fluids through a spinning-based pumping mechanism made possible by its shaftless propeller structure. Experiments conducted within 3D-printed artificial tubes revealed the robot’s potential applications in complex biomedical environments, such as the treatment of the vascular system and the gastrointestinal tract.

“By combining shaftless propeller structure with magnetic drive technology, MSPM aims to break through the limitations of existing magnetic miniature robots in fluid manipulation and motion capabilities, providing a solution with broad application potential,” said Yaozhen Hou, a researcher at Beijing Institute of Technology. “We anticipate that the MSPM holds great potential as a minimally invasive device for thrombosis treatment and targeted medicine delivery.”