Fig. 4. Droplet transport demonstrations.

(A) “Vertical transport,” i.e., a vertically climbing water-glycerol droplet at a constant speed of 0.57 mm s⁻¹ (movie S4). (B) “Ceiling transport,” i.e., transport of a droplet (isopropanol-water mixture) at a constant speed of 0.57 mm s⁻¹ on a fully reversed (upside down) surface (movie S5). (C) “Mass transport of multidispersed droplets,” i.e., water droplets sprayed on an inclined traveling surface wave taken along with the wave (movie S6). (D) “Self-cleaning surface,” i.e., transporting droplets picking up calcium carbonate contaminating particles (movie S7). Photo credits: (A) E.D.J. and (B to D) Y.W.