Fig. 4. Phase-controlled mixing.

a MI versus phase difference for the biasing scheme 1 with $\mathrm{\Delta }{\theta }_{V_{\mathrm{gs}}}$ changing. b Grayscale fluorescent images of the channel output showing the mixing of DI water (dark) and fluorescein solution (bright) corresponding to plot in (a) for the confluent flow rate of 4 µL/min. c MI versus phase difference for the biasing scheme 2 with $\mathrm{\Delta }{\theta }_{V_{\mathrm{ds}}}$ altering. d Grayscale fluorescent images of DI water and fluorescein solution corresponding to plot in (c) for the confluent flow rate of 4 µL/min