Swimmers at low Reynolds number driven by Quincke rotation

In biological systems, the rotation and oscillation of flagella and cilia play important roles in realizing certain functions, such as self-propulsion and fluid mixing. Most previous attempts to build artificial small swimmers use an oscillatory drive. Here we present an artificial swimmer at low Reynolds number driven by an elasto-electro-hydrodynamic instability [1] based on Quincke rotation: a sphere in oil rotates in the presence of a high DC electric field. In our experiments, by attaching thin elastic fibers to a solid plastic sphere, we created swimmers that exhibit diverse behaviors when varying different control parameters. We demonstrate that the flexibility of the fibers leads to multiple stable states, where the swimmer can have unidirectional rotation or oscillatory motion controlled by the applied field. Furthermore, we relate these modes of motion to the kinematic properties of the swimmer such as the rotational speed and the ability to generate locomotion.

[1] L. Zhu and H. A. Stone, Phys. Rev. Fluids, 4, 061701(R), 2019.