fig3

Figure 3. (A) Thermography images of the movement of the light-driving actuator at different time points; (B) Relationship between driving characteristic and light intensity of actuator with the original surface; (C) Relationship between driving characteristic and light intensity of actuator with superhydrophobic surface; (D) Schematic of actuator with different surface structures based on Marangoni effect. γ_L is the surface tension with low temperature. γ_H is the surface tension with high temperature. F_b is a propulsive force caused by a buoyant flow. F_d is the resultant propulsive force. F_f is the friction resistance.