A research team from the Ulsan National Institute of Science and Technology (UNIST), led by Professor John Chong from the Department of Physics, has recently discovered a groundbreaking principle of motion at the microscopic scale. Their findings show that objects can achieve directed motion by periodically changing their size in a liquid crystal medium. This innovative discovery has significant potential for many fields of research and could lead to the development of miniature robots in the future.

In their study, the team observed that air bubbles in the liquid crystal could move in one direction and change their size periodically, unlike the symmetric growth or contraction typically seen in air bubbles in other environments. Researchers were able to demonstrate this extraordinary phenomenon by inserting air bubbles the size of a human hair into the liquid crystal and adjusting the pressure.

The key to this phenomenon is the formation of phase defects along with air bubbles in the liquid crystal structure. These defects disrupt the symmetrical nature of the bubbles, allowing them to experience a unidirectional force despite their symmetrical shape. As the air bubbles fluctuate in size, they move in a fixed direction, pushing and pulling on the surrounding liquid crystal, defying the normal laws of physics.

“This groundbreaking observation demonstrates the ability of symmetrical objects to exhibit directional motion through symmetrical movements, a previously unseen phenomenon,” said Sung-Joe Kim, first author of the study. Additionally, he highlighted the applicability of this principle to a wide range of complex fluids beyond liquid crystals.

Professor Jeong commented: “This intriguing result highlights the importance of symmetry breaking in both time and space for movement at the microscopic level. It also promises to advance research in the development of microscopic robots.”