Liquid Metal Motor

In the last decade, swimming motors for navigation in complex fluid environments have received significant attention. As an emerging material, liquid metal shows great potential for further development of swimming motors due to its unique flexibility, reconfigurability, and stimulus responsiveness. The present laboratory found for the first time that liquid metal can move spontaneously in alkaline solution after swallowing aluminum. Based on this, via direct injection, the liquid metal containing aluminum can maintain the ability to move even after dispersing into millimeter-sized tiny droplets. Therefore, these tiny droplets are also called liquid metal motors. This process is highly efficient to operate and does not require complex equipment conditions to obtain autonomously operating soft motors in bulk and quickly. In addition to this chemical approach, liquid metals have also achieved strong self-propulsion in response to external field stimuli, including electric, magnetic, acoustic and optical fields, and corresponding hybrid propulsion. Liquid metal motors offer new and unique capabilities in the field of swimming motors, allowing not only directional movements, but also deformations due to their liquid nature. This chapter will first present the typical characteristics of liquid metal motors. Then, the different principles and methods behind the fabrication and propulsion of liquid metal motors will be illustrated, including the compounding of special materials and the use of external field stimulation. Finally, the possible applications and challenges of liquid metal motors will be summarized.