Figure 3.

Three gears of bubble growth and ejection. (a) Gear 1 features a long growth period outside the motor and large bubble size. (b) Gear 2 features a short growth period inside the motor and medium bubble size. (c) Gear 3 features a negligible growth period and immediate ejection of small bubbles. (d) Time lapse of Mg-TiO₂ micromotor demonstrating Gears 1 and 2 for two consecutive bubbles. (e) Speed of the micromotor from (d) over a longer (8.5 s) span. (f) (A) Time to eject a bubble for the 8.5 s span of the micromotor from (d) providing distinction between Gear 1 (blue) and Gear 2 (red). (B) Clustering of bubble ejection time data with the mean and standard deviation. (g) (A) Bubble size for the 8.5 s span of the micromotor from (d) providing distinction between Gear 1 (blue) and Gear 2 (red). (B) Clustering of bubble size data with the mean and standard deviation. (h) (A) Motor displacement for the 8.5 s span of the micromotor from (d), providing distinction between Gear 1 (blue) and Gear 2 (red). (B) Clustering of motor displacement data with the mean and standard deviation.