Electrochemical characterization was undertaken before and after electrode modification. Figure shows typical CVs for both unmodified and modified electrodes. The bare gold electrodes exhibited quasi steady state behavior (black data) with a diffusion limited peak profile and increased hysteresis when compared to single microband electrodes. The nanogold modified electrode exhibited a higher peak current attributed to the increased surface area of the electrode when compared to the unmodified electrode. An increase in hysteresis was also observed. This diffusive limited behavior arose from analyte diffusion profiles at each band, in the IDE, overlapping resulting in the IDE behaving as a larger electrode. Figure (a) and (b) shows typical CV from a modified and unmodified electrode undertaken at different scan rates. The near overlap of peak currents is indicative of semi-steady state behavior as occurs at low scan rates of these ultra-microelectrodes. The measure peak currents presented in Figure (b) following deposition of gold deposition show a significant increase when compared to the unmodified electrodes. This may be attributed to the increased surface area of the modified electrodes as agrees with previous report . We initially investigated the use CV as the electroanalytical method of choice for EtBr in the voltage range of -00.6 to 0.6 at 100 mV/s. However, no well defined peaks were observed. To this end, square wave voltammetry 22 mV/s and 10 mV amplitude was employed. The use of a platinum on-chip reference electrode, over commercial Ag/AgCl reference electrodes, was preferred as it is solid-state and removed the need for any additional electrodes. . Figure (a) shows typical SWV obtained for different concentrations of EtBR. Well defined peaks, proportional to EtBr concentration, were observed at ~0.5v. Figure (a) shows a calibration curve plotted using the SWV peak currents presented in figure . Three different sensors were used for each concentration and, although tiny, the error bars are included in the data. Each data point represents the mean of three replicates and the error bars represent one standard deviation. The calibration curve resulted in a R 2 of 0.99 with a sensitivity (slope) of 1.5 pA/pM The theoretical LOD was calculated as 12 nM using the equation 3xSD/slope which is significantly lower than the reported literature . The SWV in figure (a) exhibited a higher background current (possibly capacitive) after the EtBr oxidation event. This suggests that the redox process was influencing / modifying the electrode in some manner possibly by electrodepositing at an electrode surface. This is known to happen at commercial macroscale glassy carbon electrodes; that are typically polished between measurements to remove any bound material. To understand if this was the case with gold electrode, we undertook further AFM analysis.