Electrically Induced Liquid Metal Droplet Bouncing br

Liquid metals, including eutectic gallium-indium (EGaIn), have been explored forvarious planar droplet operations, including droplet splitting and merging, promoting their use inemerging areas such asflexible electronics and soft robotics. However, three-dimensional (3D) dropletoperations, including droplet bouncing, have mostly been limited to nonmetallic liquids or aqueoussolutions. This is thefirst study of liquid metal droplet bouncing using continuous AC electrowettingthrough an analytical model, computationalfluid dynamics simulation, and empirical validation to thebest of our knowledge. We achieved liquid metal droplet bouncing with a height greater than 5 mm withan actuation voltage of less than 10 V and a frequency of less than 5 Hz. We compared the bouncingtrajectories of the liquid metal droplet for different actuation parameters. We found that the jumpingheight of the droplet increases as the frequency of the applied AC voltage decreases and its amplitudeincreases until the onset of instability. Furthermore, we model the attenuation dynamics of consecutivebouncing cycles of the underdamped droplet bouncing system. This study embarks on controlling liquidmetal droplet bouncing electrically, thereby opening a plethora of new opportunities utilizing 3D liquidmetal droplet operations for numerous applications such as energy harvesting, heat transfer, and radio frequency (RF) switching.