Autonomous convergence and divergence of the self-powered soft liquid metal vehicles

Conventional rigid machines, even biological systems in nature, generally do not own the capabilities like autonomous convergence or divergence. Here, such extraordinary behavior was demonstrated for the first time with the liquid metal vehicle. This synthetic soft machine fueled with an aluminum flake could initiate its autonomous locomotion in an open-top circular channel containing NaOH solution, like a running vehicle. If cutting a large machine into several smaller separately running vehicles, each of them still resumes its traveling state along the original track and chases each other. If the volumes of such dispersive vehicles were close to each other and they were all squeezed in the channel, the vehicles would move synchronously with oscillation. Otherwise, such self-motion would become desynchronized with interval between the inequable vehicles decreased gradually. If their volumes were significantly different, and the smaller vehicles were not squeezed in the channel, the faster vehicle would overtake the slower ones, until they finally coalesced seamlessly. The assembled vehicle could deform itself along with change of its velocity. This finding may shed light on future researches on smart material, fluid mechanics and soft matter to self-fueled machine and biomimics. It would also offer opportunities for constructing self-reconfigurable soft robots.