The nanocluster dendrite formation observed under the microscope (video in SI Figure ) as well as the SEM and AFM images in Figure , suggest there is always a continuous path from any point on the nanodendrites back to the working microelectrode. To test whether the nanodendrites were electrically connected to a microband, CV characterization of a modified electrode using a 10 mM ruthenium in 10 mM PBS solution was undertaken. Ruthenium was chosen as its redox reaction occurs at negative potential -and therefore away from the silver stripping potential observed at 0.1 V. Figure ((a)-(c)) shows silver nanodendrites formed following electrodeposition for 1, 5 and 12 sec, respectively, with the corresponding CVs presented in Figure (d). As can be seen, the current measured at -0.23 V (corresponding to the reduction of Ru) is 12.5 nA for a bare electrode and 12.5 nA, 13.9 nA and 13.3 nA for samples with 1, 5 and 12 s silver depositions, respectively. As the nanodendrites grow, it is expected that the measured faradaic current should grow accordingly. However, the measured signals are very similar from the ones measured at the bare microelectrode. In addition, the signal measured at 12 s electrode is smaller than the one measured at 5 sec despite the spread of the silver increasing the footprint of the electrode from 60 to 150 microns. The lack of correlation between signal intensity and electrode surface area suggests that the silver nanodendrites do not participate in the electrochemical reaction and that they are thus not fully electrically connected to the original microelectrode. However, this is good for SERS substrates as it indicates the presence of significant number of nano gaps or hotspots. The small increase observed may be attributed to an increase in surface area at the microelectrode itself. One possible explanation for the observed behavior is that after application of the deposition potential, the open potential of the electrode is close to the silver stripping potential and, as a result, silver dissolves slightly back into solution, see video S1, but does not dissolve completely.