Reversal of the flagellar motor using an optical torque

We fabricated a microstructure called a “light-mill” that rotates under optical trapping with a frequency (and torque) determined by the intensity of the trapping laser and we coupled it to the rotation of a single flagellar motor, in order to measure its torque-speed curve.
Giacomo Donini Feb 04, 2026

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An optically driven microstructure for torque measurement in rotary molecular motors

We fabricated a microstructure called a “light-mill” that rotates under optical trapping with a frequency (and torque) determined by the intensity of the trapping laser. We coupled the light-mill to the rotation of a flagellar motor and, by modifying the optical torque, we were able to measure the torque of the motor in both clockwise and counterclockwise directions.

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DOI https://doi.org/10.1038/s41378-026-01185-5