Liquid Metals: Manipulation of Liquid Metals on a Graphite Surface (Adv. Mater. 41/2016)

A liquid metal (LM) usually appears as a sphere in alkaline solution due to its large surface tension on an ordinary substrate such as glass. On page 9210, J. Liu and co-workers present a fundamental discovery that a spherical liquid-metal droplet becomes flat and dull, with its surface tension significantly reduced when placed on a graphite substrate. Such an intriguing transformation without external energy opens the way for flexibly shaping and patterning liquid-metal-based structures. Moreover, unique transformations and worm-like upslope LM locomotion under a low-voltage electric field are also revealed. These findings provide strategic insight for making future shape-controllable LM soft machines.