Figure 6

Superimposed time-lapse images of selective actuation of an acousticmicroswimmer from within a group.

Two swimmers with bubbles of different size were immersed in an acousticfield of variable frequency. (a), Swimmer A, with the larger bubble, beginsacoustically-driven motion at 74 kHz, with little simultaneous motion ofswimmer B. A video of this behaviour is available as Supplementary Video 6. (b), With further increase in frequency,swimmer A stops; swimmer B begins to move at 91 kHz, with swimmer Aremaining essentially stationary. A video of this behaviour is available asSupplementary Video 7.