Average cyclic voltammetry (CV) signals from Nile Blue DNA-modified 300, 56, and 10 µm diameter electrodes prepared on the same chip. The electrodes were assembled with 17-mer DNA duplexes of the sequence 5′-TNBGC GTC TCA GCT GAA GT-3′ and the well matched, thiolated complement. The potentials are reported versus Ag/AgCl with a CV scan rate of 50 mV/s, and each curve represents an average over four electrodes. The 300 µm electrodes show the conventional surface-bound macroelectrode redox peak, while the 10 µm electrodes show a sigmoidal CV curve, reflecting microelectrode effects.