Based on measurements of the projected area of the IDZ (Figure ), the onset time for outward IDZ growth is earlier for Ag/Au (1 s) versus the planar Au system (5 s). We attribute this lag to the time required for the IDZ to extend to the full height of the channel (z-direction) before propagating upstream and downstream from the electrode. The IDZ growth over time for the PSC/Ag/Au was comparable to the Ag/Au system (compare black and red traces, Figure ). An increase in the time to the initiation of ion depletion (to ~2 s) is attributed to an increase in the electrical and fluidic resistance of the device due to the volume occupied by the PSC beads. IDZ growth was also investigated under an applied potential of 7.0 and 10.0 V (Figure ) for all device designs. With increased potential, more rapid IDZ growth is observed and the difference in IDZ growth rate between device designs diminishes. Further stabilization of the IDZ can be achieved by flanking the 3D electrode from both sides with PSC bead beds (Figure ). However, by adding a tertiary bead bed, the overall resistance of the device increases, requiring higher voltage and applied pressure, with minimal benefit.