Fig. 4. Feedback between propulsion mechanism and particle reconfiguration.

a EHDF velocities U_i for each particle calculated from Eq. (1) with the fitting parameters β₁ = 0.23 (PS) and β₂ = 4.4 (microgel). The schematics indicate the direction of the EHDFs, being either positive (repulsive) or negative (attractive). b Experimental values (symbols) and theoretical prediction (solid line) of dumbbell velocity as a function of temperature. The inset schemes indicate the EHD flows and final propulsion direction. y-error bars are the standard deviation of the velocity calculated for 45 dumbbells at each temperature. x-error bars correspond to the uncertainty in experimentally determining T. c Theoretical prediction of dumbbell velocity v as a function of T and size ratio between the PS sphere and the collapsed microgel (at 40 °C). The plot is obtained from Eq. (1) using the experimental temperature-dependent system properties (particle size and dielectric properties, solvent viscosity) as inputs and a single-temperature independent prefactor. The dashed red box highlights the experimentally accessible range of T and size ratios (the range of size ratios is estimated from the error bars in Fig. 4b). The red solid horizontal line corresponds to the black solid curve in Fig. 4b.