The world of robotics is getting smaller and smaller, which means they need to be able to adapt to smaller and smaller environments. While robots have traditionally introduced hard exteriors, the field of soft robotics is introducing a new way to construct robots with softer, bendable appendages capable of being applied to environments that involve disaster relief, laparoscopic surgery, prosthetics, and even space exploration.
When we think of liquid metal, our imaginations often turn to the purview of science fiction, specifically the T-1000 from the famous movie, “Terminator 2”, which featured a robot capable of going from a solid state of matter to liquid at will.
But science has a way of turning science fiction into science fact, which has been presented in a recent study published in the journal Matter, where an international team of researchers led by the Shenzhen Campus of Sun Yat-sen University in China have developed miniature robots capable of shifting between solid and liquid states of matter along with being magnetic and capable of conducting electricity. This study holds the potential to advance the field of soft robots, which have traditionally demonstrated flexibility but possess a weak mechanical structure, which also raises the difficulty of controlling their movements.
For the study, the researchers invented a novel phase-shifting material known as "magnetoactive solid-liquid phase transitional machine" where them implanted magnetic particles within the metallic element gallium, which possesses a very low melting point of 85.64 degrees Fahrenheit.
"The magnetic particles here have two roles," said Dr. Carmel Majidi, who is a Clarence H. Adamson Professor at Carnegie Mellon University, and a co-author on the study. "One is that they make the material responsive to an alternating magnetic field, so you can, through induction, heat up the material and cause the phase change. But the magnetic particles also give the robots mobility and the ability to move in response to the magnetic field."
By using a magnetic field to induce the phase change, this contrasts present phase-shifting materials, which traditionally require external heat sources such as electrical currents or heat guns to induce the phase shift. This new material is also far less viscous than traditional “liquid” phases of other phase-shifting materials, as well.
Using the magnetic field, the new soft robots were subjected to a variety of tests, including climbing over walls, jumping over moats, and even splitting in half where each half worked together to move around objects before joining back together. One such person-shaped robot even liquified to ooze through a grid and molded back to its original shape afterwards, as depicted in a video.
"Future work should further explore how these robots could be used within a biomedical context," said Dr. Majidi. "What we're showing are just one-off demonstrations, proofs of concept, but much more study will be required to delve into how this could actually be used for drug delivery or for removing foreign objects."
Such future work includes circuit repairment, smart assembly using smart soldering machines and universal screws, and foreign object removal and drug delivery for the human body, as outlined in the paper.
Laurence Tognetti is a six-year USAF Veteran who earned both a BSc and MSc from the School of Earth and Space Exploration at Arizona State University. Laurence is extremely passionate about outer space and science communication, and is the author of "Outer Solar System Moons: Your Personal 3D Journey".
