A research team in South Korea has developed a liquid-based robot capable of freely changing shape, splitting, and fusing—much like living cells.
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Seoul National University’s College of Engineering announced that the breakthrough was achieved through a collaboration led by Professor Ho-Young Kim (Department of Mechanical Engineering), Professor Jeong-Yun Sun (Department of Materials Science and Engineering), and Professor Keunhwan Park (Department of Mechanical, Smart, and Industrial Engineering) at Gachon University. Their findings were published on March 21st in the journal Science Advances.
Biological cells are known for their remarkable ability to deform, divide, fuse, and even engulf foreign substances. For years, scientists have tried to replicate these dynamic behaviors in artificial systems. Yet, traditional solid-based robots have consistently struggled to match the flexibility and responsiveness of their biological counterparts.
To tackle this challenge, the joint research team created a next-generation soft robot made from liquid and encased in a shell of densely packed hydrophobic (water-repellent) particles. This design allows the robot to combine the extreme malleability of liquid with the structural stability of a solid. As a result, it can endure intense pressure or impact—such as being dropped from a height—and bounce back to its original form, much like a droplet.
Drawing on these strengths, the researchers demonstrated the robot’s capabilities through a series of experiments. Echoing the liquid-metal T-1000 robot from Terminator 2, the device can slip through tight metal bars, pick up and carry foreign objects, merge with other liquid robots, and move across both water and solid surfaces. They also developed a technique for controlling its movement at specific speeds using ultrasound waves.
Thanks to its adaptability, the liquid robot holds promise for a wide range of applications. In biomedicine, it could be used for targeted drug delivery or minimally invasive therapeutic procedures inside the body. Its ability to navigate narrow, complex spaces also makes it a strong candidate for deployment in machinery maintenance, disaster response, and environmental cleanup—performing tasks like exploration, chemical removal, and nutrient supply in hard-to-reach areas.
When we first started developing the liquid robot, we initially considered encapsulating a spherical droplet with particles, just as adopted in making conventional liquid marbles. However, by shifting our perspective, we came up with the idea of coating an ice cube with particles and then melting it, which significantly enhanced the stability of our robots.
Hyobin Jeon, Study First Author, Seoul National University
Professor Ho-Young Kim, the Corresponding Author, remarked, “Building upon our current findings, we are now working on technologies that will allow the liquid robot to change shape freely using sound waves or electric fields.”
We plan to enhance the material functionality of the liquid robot to enable broader industrial applications in the future.
Jeong-Yun Sun, Professor and Study Co-Corresponding Author, Seoul National University
Journal Reference:
Jeon, H., et al. (2025) Particle-armored liquid robots. Science Advances. doi.org/10.1126/sciadv.adt5888.