<p>➀ Researchers at the University of Gothenburg developed micro-gears smaller than a human hair using silicon wafer fabrication techniques;</p><p>➁ These gears are powered by laser light interacting with metasurfaces, enabling spin control via light intensity;</p><p>➂ The micro-gears can operate for hours, are tested with lubricating liquid, and integrated on chips for scalable applications.</p>