Observation of Enhanced Diffusivity in Magnetically Powered Reciprocal Swimmers

We report on the development of a system of micron-sized reciprocal swimmers that can be powered with small homogeneous magnetic fields, and whose motion resembles that of a helical flagellum moving back and forth. We have measured the diffusivities of the swimmers to be higher compared to nonactuated objects of identical dimensions at long time scales, in accordance with the theoretical predictions made by Lauga Phys. Rev. Lett. 106, 178101 (2011)]. Randomness in the reciprocity of the actuation strokes was found to have a strong influence on the enhancement of the diffusivity, which has been investigated with numerical calculations.