Fig. 2.

LAF-1 droplets are homogeneous fluids with salt-dependent viscosity. (A) Confocal image sequence showing LAF-1 droplet fusion. (B) Fusion events are well fit by an exponential decay, which is used to determine fusion timescale $\tau$. (C) Decay time vs. length scale for LAF-1 droplets prepared in 125 mM NaCl. The linear slope represents the inverse capillary velocity, $\mathit{\eta }/\mathit{\gamma }\approx \hspace{0.17em}$0.12 s/μm. (D) Confocal image of red fluorescent beads embedded inside a large LAF-1 droplet. (E) Probability distribution of bead displacement for three different lag times. Distributions are well fit to a Gaussian (solid lines) indicating a homogenous environment. (F) Mean squared displacement vs. lag time. MSD data for individual beads from a single droplet are plotted. Black solid line, slope of 1; black dash, the noisefloor is $\approx$ 2 × 10⁻⁴ μm. (Inset) Representative 2D particle track. (G) Increasing concentrations of NaCl result in increased MSD of particles and decreased viscosity (Inset).