Autonomous rotation of a ratchet motor driven by active camphor particles

A ratchet motor driven by camphor floats on water was studied. As the number of particles increased, the symmetry of the ratchet's spinning direction broke and the direction favored by the ratchet structure was selected. Interaction among camphor particles generated a unique motion in one particle that triggered this symmetry breaking. The motion of other particles was influenced by the gear rotation, reinforcing the asymmetry in the circulation. This ratchet system introduced a novel concept: a ratchet powered by the interactive dynamics between the ratchet itself and the background motions.