The light-powered engine is thinner than a hair

A Swedish group of scientists has developed a laser-powered motor measuring micrometers in size. This represents a new way of thinking about micromotors, the researchers say.

As scientists from the University of Gothenburg point out, for a decade, attempts have been made to create increasingly smaller gears to construct various types of micromotors. However, progress has stalled at 0.1 millimeters because it has been impossible to build the even smaller drive systems needed to set the mechanism in motion.

A Swedish group has overcome this threshold by harnessing light power. The experts demonstrated that micromachines can be powered by optical metamaterials—small, patterned structures capable of capturing and controlling light at the nanometer scale. Using traditional lithography, they fabricated gears made of an optical metamaterial made of silicon. The gear's diameter was just a few dozen micrometers.

By illuminating the metamaterial with a laser, researchers can cause the gear to rotate. The intensity of the light controls the speed, while the direction of rotation can be changed by modifying the polarization of the light.

"We've built a gear train in which a light-driven gear sets the entire chain in motion. The gears can also convert rotational motion into linear motion, perform periodic movements, and control microscopic mirrors to deflect light," says Gan Wang, the first author of the study (https://www.nature.com/articles/s41467-025-62869-6). "This is a completely new way of thinking about microscale mechanics. By replacing massive clutches with light, we can finally overcome the size barrier."

With these advances, we can begin to imagine micro- and nanomachines that can control light, manipulate tiny particles, or be integrated into future lab-on-a-chip systems. A gear wheel can be just 16-20 micrometers in diameter, and human cells of similar size exist.

These types of systems could therefore find medical applications. "We can use the new micromotors as pumps inside the human body, for example, to regulate different flows. I'm also looking at how they function as valves that open and close," says Gan Wang.

Marek Matacz

mat/zan/

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