Fig. S1

Snapshots of the spontaneous motion of droplets at different times. (Scalebar: 1mm) (a) Spontaneous droplet motion on a level substrate with E1 = 0.4 kPa and E2 = 130 kPa (βm = 0{degree sign}). (b) Spontaneous droplet motion on a tilted substrate with E1 = 1.7 kPa and E2 = 130 kPa (βm = 3{degree sign}). (c) Bottom view of a moving droplet on a level substrate with E1 = 0.4 kPa and E2 = 130 kPa. (d) Spontaneous motion of an ionic liquid droplet on a level substrate with E1 = 0.4 kPa and E2 = 130 kPa (βm = 0{degree sign}).