The Rebound Motion of Liquid Metal Droplet on Flexible Micro/Nano Needle Forest

A polymer-based micro/nanostructured needle forest with high resistance property to liquid metal (Ga90In10, LM) droplet is reported, whose radius, aspect ratio (AR), and space can be adjusted as desired. The impact response motion of LM on the needles with different AR is observed. On the needle forest AR(5) and space of 100 m, the LM droplet can impact and rebound off easily. During the impacting processes, the flexible needles can bend under gravity of LM droplet and store energy, i.e., the kinetic energy of LM segmentally transfers into elastic energy of needles over their bending process. The stored energy in needles then turns to drive LM droplet to rebound off the surface in the recovery process. Compared with the flat surface and other needle forests with different AR(x), the AR(5) exhibits more resistance with LM. Further, the elastic theory is applied to interpret the LM driving mechanism and the reason to effectively overcome the high density of the metal droplet. The present finding suggests an important way of driving the LM droplet on micro/nanostructured surfaces which would hold big potential in heavy liquid metal transport field.