Figure 2. Generation of ferrofluid droplets in a uniform magnetic field.

(a–c) Droplet generation at the flow rate ratio 2 (Q2). (a) Schematic. (b,c) Experimental micrographs at (b) H = 0 mT and (c) H = 500 mT, scale bar = 250 μm. (d) Droplet size vs flow rate ratio (Qr) at magnetic field H = 0, 50, 100, 500, 1000 mT. Solid lines denote polynomial fits and the dotted line shows a linear fit. The inset shows the graph for the scaling law D/d = 1 + 1/Qr⁷⁰ at H = 0mT, for droplet diameter D, channel width d and flow rate ratio Qr = Q_cp/Q_dp. The purple arrow indicates the direction of the CP flow (x-direction). The magnetic field is in the y-direction. Please see Table 1 for ferrofluid properties.