A robot boat powered by liquid metal engines

Unlike conventional microelectromechanical systems (MEMS), machines based on gallium liquid metal alloys rely on Marangoni flows to induce motion without mechanical moving parts. Despite this advantage, currently developed liquid metal enabled robotic systems still need the locomotion of liquid metal droplets, thereby generating weak actuating forces and limiting their manoeuvrability. Here, a liquid metal engine (LME) is created to work as a jet thruster to continuously power a robot boat without the need of locomotion. In addition, the engine is electrically driven by surface tension without any mechanical moving parts. The structural design and the parameters of operation of the LME are investigated and optimized. Finally, the manipulation of the LME using a motor control unit is demonstrated for driving an untethered robot boat to realize complex locomotion with the precise control over the direction and speed. Thus, this LME could offer new opportunities for developing high-performance liquid metal machines to power robotic systems.