Levitating rotor with almost zero friction could soon give GPS a real backup plan
A tiny spinning disc levitating above magnets in Singapore kept turning for more than 10 hours after researchers switched off the power driving it. That level of persistence marks the lowest energy loss ever recorded for a mechanical rotor of its size. It points toward a new way to navigate when GPS signals disappear.
Scientists at the A*STAR Quantum Innovation Centre built the millimeter-scale rotor as part of a broader push into precision sensing technology. The findings were published in Nature Communications.
Levitation without contact
The rotor floats above permanent magnets using diamagnetic levitation, a technique that requires no continuous power to stay aloft. Unlike magnets that attract or repel with a fixed pole, diamagnetic materials weakly resist any magnetic field, letting them hover in place with zero energy consumption.
That kind of levitation has existed for years, but it comes with a persistent flaw. As the rotor moves through the magnetic field, it generates eddy currents, tiny electrical loops that bleed away rotational energy and slow the spin. Researchers have struggled to shrink that energy loss in rotors large enough to be practically useful.
Symmetry beats eddy currents
The A*STAR team's solution relies on rotational symmetry. Because the rotor experiences nearly the same magnetic field at every point during a full rotation, the eddy currents that would normally sap its energy get sharply suppressed.
The effect is dramatic. The rotor's spinning motion loses energy roughly 100,000 times slower than its side-to-side or up-and-down movements. That imbalance let the team measure a dissipation rate of 3.85 microhertz, the lowest ever reported for a millimeter-scale mechanical rotor.
Ten hours, no power
Using electrostatic forces and real-time feedback control, researchers spun the rotor up to 930 revolutions per minute. Once they switched off the drive in high vacuum, the rotor kept spinning under its own momentum for more than 10 hours before finally slowing down.
Lead researcher Xianfeng Chen said achieving such low energy loss in larger rotors had remained an unsolved trade-off for years. Bigger rotors interact more strongly with weak signals but typically bleed more energy. He said the new design overcomes that limitation and opens a path toward precision sensing and quantum research in larger mechanical systems.
Commercial-grade sensitivity today
The prolonged spin translated directly into gyroscope performance. The stable rotor detected rotations as slow as 0.0065 degrees per second, a sensitivity level that already meets commercial-grade standards used in existing inertial navigation hardware.
Modeling by the team suggests the platform could eventually reach navigation-grade sensitivity with further refinement. That tier would be precise enough for applications like autonomous underwater vehicles operating where GPS simply does not reach.
Bringing navigation to Singapore
A*STAR chief quantum scientist Ping Koy Lam said the achievement combines four capabilities rarely found together in one system. These include millimeter-scale passive levitation, room-temperature operation , high spin speed, and record-low rotational energy loss.
Lam credited the result to drawing on expertise across A*STAR and Singapore's broader quantum research ecosystem in control systems, levitation physics, precision engineering, and sensing. The team's next steps include pushing the rotor to spin faster and improving its long-term stability. They also plan to shrink the supporting hardware toward a size that could eventually fit inside an affordable, commercially viable navigation sensor.
