Fig. 3.

Experimental images showing the pumping behavior by indicating the movement of polystyrene beads at different time frames when (a) t₀ = 0 s, (b) t₁ = 1 s, (c) t₂ = 2 s, and (d) t₃ = 3 s. (Red, yellow, and blue circles indicate three representative groups of beads.)