Scientists develop rice grain-sized robots controlled by magnetic fields

According to the NTU team, the miniature robots may be used to reach confined and enclosed spaces currently inaccessible to existing robots, making them particularly useful in the field of manufacturing and medicine, such as in surgical procedures for 'difficult-to-reach' vital organs such as the brain.

Researchers at Nanyang Technological University, Singapore have developed millimetre-sized robots, measuring about the size of a grain of rice, that can be controlled by magnetic fields to perform highly manoeuvrable and dexterous manipulations.

The NTU researchers embedded magnetic microparticles into biocompatible polymers to create the six DoF (degrees-of-freedom) miniature robots that are claimed to improve on many existing small-scale robots. The made-in-NTU robots can rotate 43 times faster than the existing six DoF miniature robots in the critical sixth DoF when their orientation is precisely controlled.

The miniature robots can also be made with 'soft' materials and thus can replicate important mechanical qualities. For instance, one type can 'swim' like a jellyfish, and another has a gripping ability that can precisely pick and place miniature objects. Using the gripper robot, the researchers were able to assemble a 3D structure consisting of a bar sitting atop two Y-shaped stilts in less than five minutes, about 20 times faster than existing miniature robots have been able to.

Video Credit: NTUsg/YouTube

"The crucial factor that led to the team's achievement lie in the discovery of the 'elusive' third and final principal vector of these magnetic fields, which is critical for controlling such machines," explained Assistant Professor Lum Guo Zhan from the School of Mechanical and Aerospace Engineering who is also the lead author of the study.

According to the NTU team, the miniature robots may be used to reach confined and enclosed spaces currently inaccessible to existing robots, making them particularly useful in the field of manufacturing and medicine, such as in surgical procedures for 'difficult-to-reach' vital organs such as the brain.

The researchers are now looking to make their robots even smaller, on the scale of a few hundred micrometres, and to ultimately make them fully autonomous in terms of control.

The research paper titled "Small-scale magnetic actuators with optimal six degrees-of-freedom" is published online in the peer-reviewed scientific journal Advanced Materials, June 2021 issue.