Transport velocity of droplets on ratchet conveyors is determined by quantized step probability

We report the first characterization of the transport velocity for droplets driven on ratchet conveyors. Through this study, we determined that the minimum vibration amplitude to initiate droplet transport does not occur at the largest movement of the droplet edges and is thus not simply a resonance effect. We have also discovered that the transport velocity is correlated with the vibration amplitude, but ultimately determined by the probability of the droplet edges advancing by a discrete number of steps.