Fig. 5: Effect of CaCl₂ concentration in the droplet, solution depth, and container size on the frequency of spiral patterns.

a Angular velocity curve ω(t) obtained by tracking the rotation of the filament in a round cell (diameter 15.8 mm) filled with PEG-SDBS (2.5 mM) solution (depth 2.5 mm) (Supplementary Movie 3). The ω data were recorded every 0.5 s. ω < 0 because the rotation was clockwise. b Corresponding images for the three peaks in the ω(t) curve at 115.5 (θ = −13.2 π), 123.0 (θ = −14.2 π), and 130.5 s (θ = −15.2 π), respectively. c f_r(t) curve measured for the addition of a 1 μL droplet of DEX-MB-CaCl₂ containing 100 (black line), 50 (red line), 10 (blue line), and 5 (green line) mM of CaCl₂ to a round cell (diameter 15.8 mm) filled with PEG-SDBS (2.5 mM) solution (depth 2.5 mm), respectively. d f_r(t) curves obtained for spiral patterns in a round cell (diameter 15.8 mm) with a solution depth of 2.0 (black line), 2.5 (red line), 3.0 (blue line), 3.6 (green line), and 4.1 mm (purple line), respectively. The curves for 2.0 and 4.1 mm were fitted by second-order polynomials and the rest by straight lines. e Average frequency f_r(t) as a function of time for spiral patterns in round cells (solution depth 2.5 mm) with a diameter (D) of 10.4 (black line), 15.8 (red line), 22.1 (blue line), 34.6 (green line), and 54.0 mm (purple line), and a glass cuvette (24 × 24 × 24 mm) (orange line), respectively. Straight-line fits to the curves are shown. f The distance from the droplet to the wall in the glass cuvette and the 22 mm diameter round cell.