Abstract. There are many different strategies to overcome the scallop theorem present in literature. We focus on how to obtain a net motion and consequently con- trollability, exploiting the fluid’s type change during a periodic deformation. We are interested in two different models: in the first one that change is linked to the magnitude of the opening and closing velocity. Instead, in the second one it is related to the sign of the above velocity. An interesting feature of the latter model is the introduction of a delay-switching rule through a thermostat. We remark that the latter is fundamental in order to get both forward and backward motion and therefore global controllability.