A levitated rotor spins for 10 hours, pointing to GPS-free navigation

In a high-vacuum chamber in Singapore, a graphite rotor floats above permanent magnets as lasers and electrodes track its motion. When ASTAR researchers switched off the drive, the millimeter-scale rotor kept spinning for more than 10 hours*—a new low-energy-loss benchmark for a mechanical rotor of its size.

The obstacle was not friction at a bearing: there was no bearing touching the rotor. Diamagnetic levitation has instead been held back by eddy-current damping, in which magnetic effects drain energy from motion. The A*STAR Quantum Innovation Center team used rotational symmetry to reduce that loss. As the rotor turned around its central axis, it encountered almost the same magnetic field on every rotation, suppressing the currents that would otherwise slow it down.

The result was a rotational dissipation rate of 3.85 microhertz. Energy loss in the rotor's spinning motion was around 100,000 times slower than in its sideways and vertical movements. That stability gave the researchers enough time to use the device as a gyroscope, a sensor that measures changes in orientation.

The system reached 930 revolutions per minute and detected rotations as slow as 0.0065 degrees per second, placing its sensitivity within the commercial-grade range. The study, published in Nature Communications, says modeling points toward the more demanding navigation-grade range with further development.

So what changes in practice? A stable gyroscope could help vehicles maintain accurate orientation underground, underwater or in other places without GPS signals. The immediate beneficiaries would be systems such as autonomous underwater vehicles, but the device is not yet a field-ready product: A*STAR says the next steps are higher speed, better stability, more compact support hardware and a commercially viable sensor platform.