Figure 2

Rotation behavior of microrotors in the coalescent microdroplets. The top pictures show rotating microrotors with angular velocities of (a) 15 rad s^–1, (b) 21 rad s^–1, (c) 32 rad s^–1, (d) 45 rad s^–1, (e) 66 rad s^–1 and (f) 98 rad s^–1. These snapshots were taken every 33 ms. The scale bars indicate 1 mm. (g) The time evolution of the rotational angle θ of microrotors in the coalescent microdroplets. The dashed lines are the best-fit lines using the linear functions with respect to t.