The outcome of a representative fingerprint enhancement is shown in Figure 1. Voltammetric responses of these laterally inhomogeneous films were consistent with those widely reported for laterally uniform films deposited on bare electrodes.The presence of the initial sebaceous print (not shown) was visible with the aid of suitable lighting and viewing angle, but details could not be discerned at a level adequate to permit identification. Although the fingerprint deposit clearly locally inhibits the electrochemistry that underlies polymer deposition and redox switching, it does not do so on the intervening inter-ridge areas, where there is deposition of polymer that is addressable by the underlying electrode. Figure 1 shows selected images captured at applied potentials generating distinct film colors. More detailed appraisal of the visual contrast manipulation was provided by video imaging (capture rate 30 fps) under potentiodynamic conditions (see the Supporting Information).