Figure 4

Primary channel with capillary side-channels to facilitate electrolyte backflow. (a) Primary channels extending from the reservoir have a constant height h and width w. Two small capillary channels frame each primary channel. (b) When the electrolyte is introduced it fills both the primary and capillary channels, whereas the liquid metal remains only in the primary channel. During ECA actuation Marangoni forces cause the electrolyte to flow in the opposite direction of the liquid metal, and the capillary channels provide the electrolyte with an unobstructed path into the reservoir.