Reversible actuation of water droplet penetrating GCNM under electric field. As shown in Fig. 4c, one droplet (5μl) was placed on the mesh, while another droplet of the same size was positioned underneath the mesh. A Cu tape electrode was located above the mesh. By applying an electric field up to 13.75 kV/cm, the droplet underneath the mesh moved to the upper droplet through the mesh, and the ... [Show full abstract] fused droplets moved toward the Cu electrode. When the applied voltage was decreased to 0 kV, the droplets returned to their original shapes.