Run-and-Tumble-like dynamics of Quincke rollers actuated by an AC electric field

Run-and-tumble dynamics is a canonical example of swimming strategy in self-propelled microswimmers such as E. Coli. It is characterized by swimming on straight line at almost constant velocity (runs), followed by a sudden complete random reorientation of swimming direction (tumbles). Here, we experimentally show how the Quincke rollers, previously studied mainly as an active Brownian particles, can perform Run-and-Tumble-like locomotion. We achieve this by modulating the intensity and duration of the applied electric field. Through single-particle-tracking analysis, we characterize the short-term and long-term dynamics of the mean-squared-displacement of the Quincke random walkers. More specifically, it is shown how the directed motion at short times and enhanced Brownian diffusion at longer time-scales are linked to the frequency and intensity of the applied electric field. We further demonstrate how we can engineer AC Quincke rollers to create a novel artificial particle system with well-controlled tunable properties to investigate anomalous diffusion in Run-and-Tumble dynamics.